IIM patients showed significantly reduced global longitudinal PS (GLPS) and longitudinal PS at apical slice, whereas all strain parameters decreased in non-IIM patients. Except GLPS and longitudinal PS at apical slice, all strain parameters in non-IIM patients were lower than those in IIM patients. By Pearson’s correlation analysis, the LV global radial and circumferential PS were correlated to N-terminal pro-brain natriuretic peptide level and LV ejection fraction in both IIM and non-IIM patients. This study indicated that CTD patients showed abnormal LV deformation despite with preserved LVEF. The impairment of LV deformation differed between IIM and non-IIM patients.The aim of this study was to assess left ventricular (LV) myocardial strain in patients with connective tissue disease (CTD) and compare LV deformation between subgroups of idiopathic inflammatory myopathy (IIM) and non-IIM. Ninety-eight patients with CTD, comprising 56 with IIM and 42 with non-IIM, and 30 healthy subjects were enrolled and underwent 3.0T cardiac magnetic resonance imaging (MRI) scanning. The LV function and strain parameters were measured and assessed. Our result revealed that CTD patients had preserved LV ejection fraction (60.85%) and had significantly decreased global and regional peak strain (PS) in radial, circumferential, and longitudinal directions (all  Given that the cardiovascular manifestations in CTD can be clinically non-specific and insidious2, it is imperative for physicians to detect cardiac involvement early, before subclinical left ventricular (LV) dysfunction progresses to irreversible heart failure.Cardiovascular complications in patients with CTD are among the leading causes of death4. As the myocardium is a modified skeletal muscle, possibilities are that the immune-mediated inflammation also acts in myocardial disease in patients with IIM5. In other CTD, the underlying mechanisms of myocardial involvement are not fully understood; while, consequent autoantibody-related injury in the myocardium has been reported6.IIM is characterized by muscle weakness and inflammatory cell infiltration in skeletal muscle8. However, to the best of our knowledge, few studies have evaluated myocardial dysfunction in patients with CTD using cardiac MRI tissue tracking10. Furthermore, there exists limited information regarding the differences in LV deformation between IIM and other CTD. Therefore, the present study aimed to quantitate the V myocardial systolic strain in patients with CTD and investigate whether the LV myocardial deformation was different between patients with IIM and non-IIM.Cardiac magnetic resonance imaging (MRI) tissue tracking has recently been developed for the assessment of myocardial deformation and subclinical cardiac dysfunction prior to a reduction in the LV ejection fraction (LVEF)p < 0.05]. In patients with CTD, LVEF was preserved (LVEF > 50%) in both the IIM [63.9 ] and non-IIM [56 ] group. The LV function parameters, including LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), LV stroke volume (LVSV), showed no differences between the normal controls and patients with CTD .All basic characteristics are summarized in Table p < 0.001; GCPS, −20.9 ± 1.9 vs. −18.5 ± 5.1%, p = 0.019; GLPS, −10.4 ± 3.2 vs. −8.3 ± 2.8%, p = 0.001].The magnitude of regional PS in all three directions was also significantly decreased .The global and regional strain parameters of all subjects are shown in Table p = 0.006) and longitudinal PS at the apical slice  were significantly reduced in the IIM group, whereas the magnitude of all global and regional strain parameters in the three directions were decreased in the non-IIM group . In the non-IIM group, the magnitude of all strain parameters in the radial, circumferential, and longitudinal directions were lower than those in the IIM group, with the exception of GLPS and longitudinal PS at the apical slice   analysis identified GRPS , GCPS  and GLPS  to differentiate IIM from non-IIM.p = 0.005) and GCPS and GLPS were positively correlated with NT-proBNP level . In the IIM group, NT-proBNP was correlated with GRPS , as well as GCPS  and there was no correlation between NT-proBNP and GLPS   , GCPS , and GLPS  in the non-IIM group. In the IIM group, LVEF was also associated with GRPS , GCPS , and GLPS  14. While, there exists accumulating evidence emphasizing the role of cardiac MRI tissue tracking in overcoming the shortcomings of low tissue resolution and dependency of an acoustic window in STE for the evaluation of myocardial strain and cardiac dysfunction15.Cardiac involvement in patients with CTD is mostly subclinical and may lead to cardiac-related death due to myocarditis, myocardial fibrosis, valve disorders, coronary vasculitis, and pericarditisIn the present study, we applied cardiac MRI tissue tracking to evaluate LV myocardial systolic strain in patients with CTD and compared LV deformation between IIM and non-IIM subgroups. The main findings were: (1) patients with CTD had impaired global and regional LV systolic strain in the three directions, even though the LVEF was preserved; (2) compared with normal controls, the damaged strain in IIM patients mainly involved GLPS and longitudinal PS at the apical slice, whereas all strain values were impaired in non-IIM patients; (3) with the exception of GLPS and longitudinal PS at the apical slice, the magnitude of all strain parameters in non-IIM patients were lower than those in IIM patients; and (4) GPRS and GCPS showed correlations with LVEF and NT-proBNP level in both IIM and non-IIM patients.16. Recently, CMR tissue tracking has been gradually used to quantitatively measure LV function via different strain parameters from the radial, circumferential, and longitudinal directions18 with high sensitivity and reproducibility20. One of the findings of the present study was that, compared with healthy controls, the magnitude of global and regional PS in the three directions was decreased in CTD patients with preserved LVEF, which is consistent with STE results13. This finding may assist the explanation of the impairment of LV deformation detected by cardiac MRI tissue tracking prior to conventional LVEF in patients with CTD. Another finding was that GRPS, GCPS, and GLPS were correlated with LVEF in patients with CTD, which is similar to the previous literature reports in other diseases21.The LV wall is composed of cardiomyocytes, of which the orientation continuously rotates from epicardium to endocardium23. In our research, IIM patients with preserved LVEF were found to have impaired strain manifested as the magnitude reduction in GLPS and longitudinal PS at the apical slice, suggesting subclinical LV myocardial systolic impairment. Previous literature has been reported that IIM patients showed impaired LV myocardial microvascular dysfunction25, and that the abnormal LV myocardial deformation was associated with microvascular dysfunction in other diseases26. Thus, we presume that the magnitude reduction in longitudinal myocardial strain of IIM patients in our present study may be related to microvascular ischemia. Analogous to our results, recent studies have reported that IIM patients with preserved LVEF have decreased global longitudinal strain23. Guerra et al.22 described impaired longitudinal strain involved in the basal and mid-segments detected by STE, which is not consistent with our findings in the apical segment. The reasons for this discrepancy might be related to the difference in techniques used to measure LV deformation or the heterogeneity of patient populations. In addition, compared with healthy subjects, the magnitude of global and regional PS in the three directions was decreased in non-IIM patients with preserved LVEF, which is in agreement with previous reports demonstrating subclinical cardiac systolic dysfunction in other CTD besides IIM, such as SLE, RA, and SSc, as detected by STE27.An increasing number of studies have shown subclinical cardiac dysfunction in IIM patients detected by STEOur research revealed that the magnitude of all strain values in non-IIM patients were lower than those in IIM patients . Taken together, these findings support that impairment of LV deformation is different between IIM and non-IIM patients. We presume that myocardial damage manifesting as myocardial perfusion dysfunction and fibrosis differ between IIM and non-IIM. Thus, further studies are required to explore the relationships between LV deformation and the aforementioned myocardial damage detected using multi-parametric cardiac MRI, such as first-pass perfusion and late gadolinium enhancement (LGE) in IIM and non-IIM. In our present study, there was no difference between IIM patients and non-IIM patients in GLPS, and this finding might be contributed to explain GLPS was relative poor parameter  to differentiate IIM patients from non-IIM patients. Furthermore, the data obtained from the ROC analysis supported that the combination of GRPS and GCPS might be a better parameter than any one alone to differentiate IIM patients from non-IIM patients with a relative high sensitivity and specificity.28. Myocardial cell injury induced by persistent systemic inflammation and immune dysfunction could increase NT-proBNP level in CTD29. In the present study, NT-proBNP in non-IIM patients was higher than that in IIM patients, suggesting that the severity of myocardial damage might be different between IIM and non-IIM. Another finding demonstrated that NT-proBNP level was correlated with the global strain parameters in the three directions, which might indicate that LV global deformation is related to myocardial injury in patients with CTD. Similar to our findings, NT-proBNP has been reported to be increased in patients with CTD and correlated with subclinical cardiac disease30.NT-proBNP is a biologically inactive N-terminal fragment of the active hormone BNP, which is secreted by the myocardium when stimulated by an increase in ventricular overload, ventricular wall stretchesor stress, and is a standard marker of myocardial damageThe limitations of this study include the following: first, this was a retrospective and single center study, and potential center-specific bias cannot be excluded. Second, LGE data was not involved in our present study and the relationship between LV deformation and myocardial damage detected by cardiac MRI first-pass perfusion or LGE technologies is not known; thus, further studies are required to explore this. Finally, although cardiac MRI tissue tracking demonstrated high reproducibility, the accuracy needs to be further verified because of the absence of a reference standard.In conclusion, patients with CTD showed impaired LV deformation detected by cardiac MRI tissue tracking, even though they had preserved LVEF. The impairment of LV deformation was different between IIM and non-IIM patients. Early detection of subclinical impaired LV deformation may help to screen high-risk patients with CTD for early treatment.31. Informed consent was obtained from all subjects.The study cohort retrospectively enrolled 121 patients with CTD at our hospital from January 2015 to January 2019. CTD was diagnosed according to the criteria of the American College of Rheumatology or the European League Against Rheumatism, respectively. The exclusion criteria included coronary artery disease, cardiomyopathy, congenital heart disease, heart valve disease, and contraindication for cardiac MRI. Finally, 98 patients with CTD  were eligible for the study, including 56 patients with IIM and 42 patients with non-IIM . Considering the variety of CTD, these patients were divided into two subgroups: the IIM group (n = 56) and the non-IIM group (n = 42). A total of 30 age- and gender-matched healthy volunteers  with no history of cardiovascular or systematic disease were included as the normal controls. All participants underwent cardiac MRI scanning and were examined for the clinical marker, NT-proBNP. The study protocol was approved by the West China Hospital of Sichuan University Biomedical Research Ethics Committee and conducted in an accordance with the ethical guidelines of the Declaration of Helsinki (2013 EDITION)All patients were examined using a 3.0T whole-body scanner with a 32-channel phase-array cardiovascular coil . All participants were examined in the supine position. The breath-hold technique and a manufacturer’s standard electrocardiographic gating device were used for monitoring the participant’s breathing and electrocardiogram values, respectively. The continuous data were acquired during the breath-holding period. A series of 8–12 continuous cardiac MRI cine sections were acquired in the short-axis from the mitral valve level to the LV apex using a balanced steady state free precession (bSSFP) sequence . The cardiac cine series in the long-axis two-, three-, and four-chamber views were also obtained.32. LV myocardial strain measurement was performed by loading short-axis, long-axis two- and four-chamber slices into the three-dimensional tissue tracking module33. All series of the endocardial and epicardial borders were outlined manually in each slice at the end-diastolic period (reference phase)  strain parameters, including the myocardial PS in the radial, circumferential, and longitudinal directions, were obtained automatically using the aforementioned software.Post-processing of all images was performed offline by two experienced radiologists using commercial software . The LV functional parameters, including LVEDV, LVESV, LVSV, and LVEF were calculated using the aforementioned software following manual contouring of the endocardial and epicardial borders at the end-diastolic and end-systolic periods of the short-axis cine images with the papillary muscles and moderator bands included. Reduced LVEF was defined as <50%Intra-observer variability was assessed by comparing the tissue tracking measurements obtained randomly among 30 individuals by the same observer at an interval of 2 weeks. Inter-observer variability was also obtained randomly among 30 individuals and was determined by comparing the independent tissue tracking measurements of two experienced and double-blinded observers.t-test or Mann–Whitney U test, whereas those parameters among normal controls, IIM and non-IIM subgroups were compared by one-way repeated analysis of variance (ANOVA) or the Kruskal–Wallis rank test, as appropriate. Least-Significant-Difference test was used for multiple pairwise comparisons among the three groups of normal controls, IIM group, and non-IIM group when the p-value of one-way ANOVA was less than 0.05. Pearson’s correlation was used to evaluate the relationship between strain parameters and NT-proBNP and LVEF. ROC analysis was performed to determine whether the global strain parameters can be used to differentiate IIM from non-IIM patients. Intra- and inter-observer variabilities for reproducibility were assessed using the ICC. A two-tailed p value of < 0.05 was considered statistically significant.Statistical analysis was performed using IBM SPSS Statistics for Windows . All continuous variables were tested for normality using the Kolmogorov–Smirnov test. The homogeneity of variance was assessed using Levene’s test. Continuous variables are expressed as the mean ± standard deviation (SD) or the median (interquartile range). LV function and strain parameters between normal controls and CTD groups were compared using a Student’s Left Ventricular Deformation in Patients with Connective Tissue Disease: Evaluated by 3.0T Cardiac Magnetic Resonance Tissue Tracking


A pouch protruding from the free wall of the left ventricle may be either a congenital ventricular diverticulum (CVD) or aneurysm (CVA). Being aware of these rare congenital anomalies is critical in making the diagnosis. Differentiating the two is important for treatment decisions. We describe a patient with dextrocardia, Tetralogy of Fallot, and a congenital left ventricular apical diverticulum diagnosed following the induction of anesthesia. CVD and CVA may present in the antenatal period through late adulthood with differing morphology, location, and symptoms. Echocardiography is paramount in the diagnosis and characterization of these lesions. If this anomaly is encountered after the induction of anesthesia or during intraoperative echocardiography, the cardiothoracic anesthesiologist should make the surgical team aware so it can be further characterized and a treatment plan made prior to incision. A pouch protruding from the free wall of the left ventricle may be either a congenital ventricular diverticulum (CVD) or aneurysm (CVA). Both have distinct presentations, morphology, associated defects, and prognosis. Differentiating the two is important for treatment decisions. We describe a patient with dextrocardia, Tetralogy of Fallot, and a congenital left ventricular apical diverticulum diagnosed following the induction of anesthesia and review the importance of this potentially fatal condition. Written permission was obtained for presentation of this case and patient images.A male infant was born at 38 weeks of gestation by cesarean section for nonreassuring heart rate and premature rupture of membranes. A prenatal diagnosis of dextrocardia and Tetralogy of Fallot was suspected. Apgars were 9 and 9 at one and five minutes. On physical exam, the child had normal saturations on room air and a 3/6 systolic murmur heard best at the left upper sternal border. Chest X-ray revealed mild cardiomegaly with increased pulmonary vascular markings. Electrocardiogram showed right ventricular hypertrophy. Initial cardiac echocardiography evaluation revealed dextrocardia, Tetralogy of Fallot with subvalvular pulmonary stenosis, anterior malalignment ventricular septal defect (VSD), small muscular VSD, persistent left superior vena cava (LSVC), secundum atrial septal defect (ASD) and normal pulmonary valve morphology. The child did well in the newborn period and was discharged home on no medications with a diagnosis of pink Tetralogy of Fallot. Over the next several months, the child developed signs of heart failure and poor growth and treatment was initiated with diuretics and high-calorie formula. The physical exam was notable for a right-sided point of maximal impulse (PMI), an active precordium that appeared to extend to the subcostal area and an umbilical hernia. Preoperative sedated transthoracic echocardiogram showed mild main pulmonary artery (MPA) and pulmonary valve hypoplasia and suspected left pulmonary artery stenosis . A cardiac catheterization was performed and confirmed the left pulmonary artery stenosis , and a left ventricular angiogram demonstrated dextrocardia and filling of both the aorta and pulmonary artery through the VSD. The child was taken to surgery for repair of Tetralogy of Fallot at 5 1/2 months of age. Following induction of anesthesia, a pulsatile mass was noted in the upper abdomen during line placement. Preoperative transesophageal echocardiography revealed a previously unseen cor triatriatum in the left atrium with flow acceleration above the mitral valve. After median sternotomy, a diverticulum was noted to be extending from the left ventricular apex tracking down the anterior abdominal wall .Following the initiation of cardiopulmonary bypass the malalignment VSD and additional muscular VSD were closed with a Dacron patch, the right ventricular outflow tract (RVOT) muscles were resected through the pulmonary valve, the ASD closed primarily, and the cor triatriatum resected. After separation from cardiopulmonary bypass the sternal incision was extended 1.5 cm into the upper abdomen. The left ventricular diverticulum was dissected out to the umbilicus and delivered into the chest with gentle traction and revealed a fingerlike pouch contracting synchronously with the left ventricle .An echocardiogram probe was placed directly on the diverticulum and demonstrated contractile muscle and blood within the cavity. A clamp was placed across the base of the diverticulum taking care to avoid the left anterior descending artery. Echocardiographic examination confirmed no change in ventricular function and the diverticulum was amputated and the defect oversewn in two layers. The patient recovered uneventfully. Review of the preoperative transthoracic echocardiography revealed a contractile pouch extending from the apex of the left ventricle and contracting synchronously with it . The divCVD and CVA are distinct entities with differing histology and presentation . The rarThe location and morphology of CVA and CVD vary with the age of presentation. CVD presenting in childhood may be divided into those presenting in the apical and nonapical regions of the heart. Those diverticula originating in the apex of the ventricle are always fingerlike contractile pouches extending into the abdomen and are associated with midline thoracoabdominal defects, congenital heart disease, and dextro or mesocardia . They arCVAs discovered in childhood are akinetic or dyskinetic protrusions extending from the free wall of the heart most commonly present in the left ventricle but may occur rarely in the right. CVAs may vary widely in size and when large compromise ventricular function . They arStudies reporting CVA and CVD presenting in adulthood describe different morphology and locations than children even when the same classification systems are applied. Fingerlike, contractile diverticulum identical to those presenting in childhood only at the apex of the left ventricle are described in adults in all regions of the left ventricle except the anterobasal and septal area and less than 3% are associated with congenital heart disease. Fifty-six percent of CVD or CVA diagnosed in adults present at the apex of the left ventricle, with nearly one in five being a CVA . The remThere have been 809 published cases of left ventricular diverticulum or aneurysms  since thIn the ante- and neonatal period, CVD and CVA are most often discovered by echocardiography while the child is being evaluated for associated cardiac defects , 23. TheNonapical diverticulum discovered in the neonatal period are most often diagnosed by echocardiography during investigation for arrhythmias. The majority of patients with nonapical diverticulum do not have cardiac dysfunction and may go unnoticed until adulthood . PatientCongenital diverticulum and aneurysms not diagnosed at birth are often asymptomatic and found later in life coincidentally during diagnostic procedures for other indications . The typCongenital left ventricular apical diverticulum when discovered at the time of surgery for associated cardiac anomalies are resected and the chamber wall closed primarily to avoid possible later complications of arrhythmia, embolic stroke, and rupture , 31. TheThe prognosis for CVAs diagnosed in the neonatal period is poor, with a survival rate of 30% reported . CongeniPatients presenting in adulthood show an overall benign course. Some authors have recommended surgical excision to avoid later complications  and otheThe etiology of congenital apical diverticulum has been postulated to be failure of fusion of the cardiac loop to the yoke sack . NonapicCongenital left ventricular diverticulum and aneurysms must be differentiated from myocardial clefts and pseudoaneurysms. A myocardial cleft is a contractile, fissurelike protrusion within the myocardium that does not extend beyond the free wall of the ventricle. Clefts contract with systole and are often obliterated in systole. They occur from defects in myocardial fascicle arrangement and are of no prognostic significance. False aneurysms are composed of pericardium which has contained a myocardial rupture and are akinetic. They are typically the result of trauma or infarction .Congenital ventricular diverticulum and aneurysms are rare, potentially fatal anomalies. Being aware of this rare anomaly is critical in making the diagnosis. Differentiating them is imperative because of different presentations, associated disorders, prognosis, and treatment. CVD and CVA may present in the antenatal period through late adulthood with differing morphology and symptoms. Echocardiography is paramount in the diagnosis and characterization of these lesions.


J-wave pattern has been recognized as an arrhythmic risk marker, particularly in myocardial infarction patients. Mechanisms underlying J-wave development in ischemia remain unknown. In myocardial infarction model, we evaluated activation time delay as a prerequisite of J-wave appearance and predictor of ventricular fibrillation. Body surface ECGs and myocardial unipolar electrograms were recorded in 14 anesthetized pigs. 48 intramural leads were positioned across ventricular free walls and interventricular septum. Myocardial ischemia was induced by ligation of the left anterior descending coronary artery and the recordings were done during 40-minute coronary occlusion. The local activation times were determined as instants of dV/dt minimum during QRS complex in unipolar electrograms. During occlusion, ventricular local activation time prolonged in the middle portion of the left ventricular free wall, and basal and middle portions of septum, while J-waves appeared in precordial leads in 11 animals. In logistic regression and ROC curve analyses, activation time delay at a given time-point was associated with J-wave development, and a longer activation time was associated with ventricular fibrillation appearance. In experimental coronary occlusion, activation delay in ischemic myocardium was associated with generation of the J waves in the body surface ECG and predicted ventricular fibrillation. Originally, this phenomenon was regarded as a normal variant, especially in young subjects9, but subsequently has been considered as presenting a risk marker for malignant idiopathic ventricular tachyarrhythmias5. Recent evidence suggest that appearance of the J-wave pattern in patients with acute myocardial ischemia indicates the presence of arrhythmic substrate thus further increasing arrhythmic risk15. In an experimental setting, we have recently shown the appearance of J-wave during the progression of acute ischemia, which was highly predictive for ventricular fibrillation (VF)16, however the exact mechanisms underlying J-wave development could not be elucidated from the study based on close-chest myocardial infarction model.J-wave pattern is recognized as an electrocardiographic phenomenon manifesting as an additional low-frequency wavelet during the terminal part of QRS complex or QRS/ST junction17. The direct reason for the J-wave formation has been reported to be a transmural difference in a transient outward current density. This ECG phenomenon has been shown to be accentuated by increased vagal tone and bradycardia18, an observation supporting the suggested repolarization-related mechanism for the J-wave. However, a different mechanism could operate in ischemic conditions characterized by a conduction delay in the affected regions. The study by Nakayama et al.19 demonstrated that in patients with an acute ST-elevation myocardial infarction the J-wave amplitude was augmented in tachycardia, which supported the conduction delay-related mechanism of the early repolarization pattern. Meijborg et al.20 demonstrated that reduction of sodium current led to development of the J-wave pattern. Simulation studies22 demonstrated that prolonged activation in ischemic conditions produces an “overlap” of depolarization and repolarization potentials manifesting as the J-wave pattern. However, there is a lack of evidence for this concept based on direct measurements in the in vivo whole heart.The mechanism of the J-wave genesis in acute ischemia remains controversial. There are two main lines of evidence suggesting repolarization or depolarization abnormalities to underlie this phenomenon. The first line was suggested on the basis of studies of the distribution of electrophysiological properties on a transmural axis of the canine left ventricular (LV) wedge preparationThus, contribution of abnormal depolarization to J-wave generation and VF development in the ischemic conditions is unclear. In the present study, we aimed at evaluating activation time delay as a prerequisite of J-wave appearance and predictor of VF in open-chest porcine model of myocardial infarction.Guide for the Care and Use of Laboratory Animals, 8th Edition published by the National Academies Press (US) 2011 and were approved by the ethical committee of the Institute of Physiology of the Komi Science Centre, Ural Branch of Russian Academy of Sciences. Animals were anesthetized with zoletil , xylazine  and propofol . The animals were intubated and mechanically ventilated. The thorax was opened by a midsternal incision and the pericardium was cut. In order to prevent hypothermia-related phenomena including J-wave generation and slowing of activation spread, the temperature in pericardial cavity was maintained at 37–38 °C by irrigation with warm saline and heating the room air.Experiments were performed in 14 domestic pigs . The procedures conformed to the Body surface ECGs were recorded in 6 limb leads and 6 precordial leads. The latter corresponded to the standard V1-V6, but the leads V4-V6 were shifted downward to the level of xiphoid basis in order to minimize possible thoracotomy effects. This modification also took into account the vertical position of the pig heart in the thorax.16. At the end of each experiment, the animals were euthanized by an intracardiac injection of potassium chloride overdose, the heart was excised and Evans blue dye  was injected into the LAD, left circumflex and right coronary arteries with LAD ligated. The dyed zone identified the perfused or nonischemic area  free wall, interventricular septum (IVS) and right ventricular (RV) free wall at the apical, middle and basal levels of ventricles Fig. . The eleth minute until the end of 40-minute coronary occlusion. Local activation time (LAT) in each myocardial lead was measured from the QRS onset to the instant of a minimum of dV/dt during QRS complex25. For each recording, a maximal LAT was determined as the longest LAT throughout myocardium irrespective of a lead where it was observed. The presence or absence of J wave in the body surface ECGs was checked in the same time-points. According to the consensus document6, the J-wave presence was confirmed when there was a terminal QRS notching or slurring in two or more contiguous leads except V1-V3 with J-peak ≥ 0.1 mV and no QRS prolongation in leads free of the supposed J wave.Unipolar electrograms in a total of 48 myocardial leads were continuously monitored and recorded simultaneously with body surface ECGs by means of a custom-designed high-resolution system . At least 10-seconds duration recordings were done at baseline and at 1, 2.5, 5, 10, and then every 5Data are expressed as medians and interquartile intervals. Statistical analysis was performed with SPSS 23 . Kolmogorov-Smirnov test was used to validate application of ANOVA post-hoc tests; otherwise, Wilcoxon and Fridman tests were applied for paired and multiple comparisons, respectively, within the same groups of animals. Logistic regression analysis and receiver operating characteristics (ROC) curve analysis were used to assess relationship between intramural LATs and appearance of J-waves on the surface ECG and VF development. The differences were considered significant at P < 0.05.At baseline, we observed an expected activation pattern with relatively early LATs in subendocardial and intramural myocardial layers and relatively late LATs in subepicardial layers. Rapid intramural spread of activation resulted in a nearly simultaneous excitation of different parts of ventricular myocardium [median LAT ranged from 18 (IQR 17–22) ms in the LV apex to 20 (IQR 17–22) ms in the basal IVS and 20 (IQR 19–24) ms in the middle RV] with the only exception of the RV base that was activated later than the rest of myocardium .Coronary occlusion induced typical changes of ventricular electrograms in the affected regions, essentially in the anterior parts of basal and middle areas of LV free wall and IVS, observed as a prolongation of QRS complex duration and LAT delay. LAT prolongation was nonuniform across ventricular myocardium Fig. . While tth minute of occlusion. At this time-point, a marked prolongation of LAT medians as compared to the baseline state was documented in the middle portion of the LV free wall, basal and middle portions of IVS, while the rest of myocardial regions did not demonstrate statistically significant changes of LAT   in 11 animals . ROC curve analysis . Similarly, the ROC curve analysis  as predictors of VF. The logistic regression analysis demonstrated that only IVS LATs were the independent predictors of impending VF .The main findings of the present study are as follows: (i) LAD occlusion led to LAT increase associated with J-wave appearance on the body surface ECG; (ii) impending VF was predicted by LAT prolongation in ischemic regions; (iii) the LAT associated with impending VF was significantly longer than the LAT associated with J-wave development and confined to the IVS region.17. Presenting no objections against the role of repolarization in the J-wave pattern generation in a general sense, our experimental data suggest that in the acute ischemia setting, the J-waves were strongly associated with occurrence of abnormal depolarization and were likely to be the consequence of it. Several considerations support this hypothesis.There is a long-lasting debate on the origin of the J-wave pattern. Its alternative name “early repolarization pattern” implies its relation to the repolarization process, specifically to the potential difference during action potential phase 1et al.24. Using this method that provided the means for in vivo evaluation of activation wave spread across ventricular walls, we observed the expected activation slowing in the ischemic regions with the most pronounced LAT delay being associated with the J-wave pattern. This activation delay developed progressively in time and space with transition from the typical QRS morphology to the grossly distorted wide QRS complexes which were often attended by the change of initial portion of QRS (either loss or development of the q wave) (Fig. We measured LAT as an instant of the steepest downslope of the QRS complex of unipolar ventricular electrogram. This approach was validated in an earlier study by Kleber 26. Taken together, these findings suggest that the J wave can develop in conditions with prolonged activation of IVS and adjacent ventricular areas.J-wave formation was associated with LAT prolongation in specific ventricular areas. Since the site of occlusion was the proximal part of LAD artery, the areas demonstrating the significant ischemia-related activation delay were the anterior regions of the basal and middle part of IVS and middle part of LV free wall. These very areas demonstrated significant association between LATs and J-wave pattern. In previous studies, J-point elevation was reported to correlate with a thickness of IVS3. In the present study, we provided evidence suggesting J-wave association with depolarization abnormalities. Moreover, our findings suggest that further delay of LAT in the ischemia-affected myocardial region strongly predicts development of ischemia-induced VF.Whatever the cause of the J-wave pattern, this electrocardiographic phenomenon appears to be a risk factor for malignant ventricular tachyarrhythmiasLAT prolongation was associated with impending VF in a manner similar to LAT association with J-wave pattern. However, LAT predicting VF were longer than those predicting J-wave pattern for the similar levels of sensitivity and specificity Fig. . It coulIn the present investigation, only one locus of coronary occlusion was studied. It is plausible that different occlusion sites should have produced a different size and location of myocardial lesion, which could have resulted in a different electrophysiological and ECG manifestation. The positions and number of intramyocardial leads were limited due to technical reasons and could not ensure a complete “capture” of the ischemic area. This technical limitation at least partly explains the relatively low sensitivity of the LAT parameters. The limited number of animals and endpoints requires cautious interpretation of the data. However, our approach based on continuous multiple-lead potential recordings permitted relating electrophysiological events in the identified ischemic area to simultaneously recorded ECG phenomena that enhanced the quality of obtained results.The present study demonstrates that in experimental LAD occlusion model, activation delay in ischemic myocardium is associated with the generation of J-wave pattern. More pronounced LAT prolongation in the IVS expressed in J-wave pattern predicted impending VF. Abnormal depolarization in ischemic myocardium could present a “missing link” between J-wave pattern and arrhythmic risk in conditions of acute myocardial infarction.


Global left ventricular (LV) function is routinely used to assess cardiac function; however, myocardial strain is able to identify more subtle dysfunction. We aimed to determine the recovery and prognostic value of featuring tracking (FT) cardiovascular magnetic resonance (CMR) strain in ST-segment elevation myocardial infarction (STEMI) patients with a concurrent chronic total occlusion (CTO).In the randomized EXPLORE trial, there was no significant difference in global LV function after percutaneous coronary intervention (PCI) of the CTO, compared with no-CTO PCI, post-STEMI. In the current study, we included 200 of the 302 EXPLORE patients with a baseline CMR, of which 180 also had 4-month follow-up  CMR. Global longitudinal strain (GLS) was calculated from 3 long-axis views. Global circumferential strain (GCS) and segmental strain were calculated from 3 short-axis views .p < 0.001; GCS ∆ − 1.7 ± 4.7%, p < 0.001); however, there was no treatment effect of CTO-PCI on strain recovery. GLS was a significant predictor for 4 months of LV ejection fraction (p = 0.006), incremental to other CMR parameters including infarct size. For mortality, infarct size remained the strongest predictor. On regional level, segmental strain independently predicted recovery in the dysfunctional segments (p < 0.001).Global strain significantly improved at 4 months  contains supplementary material, which is available to authorized users. Cardiovascular magnetic resonance (CMR) is frequently used for non-invasive assessment of global left ventricular (LV) function and infarct size, which can be used as surrogate endpoints to predict clinical outcome of ST-segment elevation myocardial infarction (STEMI) patients . HoweverIn STEMI patients with a concurrent chronic total occlusion (CTO), neither the recovery and prediction of outcome using global and segmental strains have thus far been examined nor the effect of additional percutaneous coronary intervention (PCI) of the CTO on the recovery of strain. Currently, the treatment of the (accidently) found concurrent CTO in STEMI patients during primary PCI remains controversial. Observational data have suggested beneficial effects of CTO-PCI . Howevern = 102) were excluded because they lacked a baseline CMR (a baseline CMR was not mandatory in the study protocol). Details regarding the design and results of the EXPLORE trial were previously reported [n = 148) or to a conservative strategy (no-CTO PCI) for at least 4 months (n = 154). Important inclusion criteria were the following: a concurrent CTO in a non-infarct-related artery found during successful primary PCI for STEMI and the CTO had to be located in a coronary vessel with a reference diameter of at least 2.5 mm. Among the exclusion criteria were the following: > 48 hemodynamic instability and factors precluding reliable CMR imaging . Full inclusion and exclusion criteria are summarized in the In the current sub-study from the EXPLORE trial, we included all patients who underwent a baseline CMR (200 of the 302 patients), of which 180 patients also had a 4-month CMR . This cohort of patients with serial CMR has been described before . In thesreported . In shorAll CMRs were performed on a 1.5-Tesla scanner using a dedicated phased array cardiac receiver coil. ECG-gated steady-state free-precession cine images for LV function imaging were obtained, during repeated breath holds, in long-axis orientation  and in short-axis orientation covering the left ventricle from base to apex. Late gadolinium-enhanced (LGE) images were acquired using an inversion recovery gradient-echo pulse sequence with slice locations identical to the cine images to identify the size and extent of infarction. Images were acquired at least 10 min after administration of a gadolinium-based contrast agent in a dosage of 0.2 mmol/kg of body weight. Transmurality of scar tissue of the myocardium was assessed in patients who underwent baseline CMR of sufficient quality. To assess viability, transmural extent of infarction (TEI) was used, TEI of 0–50% per segment was considered viable .The analysis of segmental wall thickening has been described before . An indep < 0.001).Strain measurements were performed offline using the FT-CMR software method of Medis QStrain Software   [p value < 0.05 was considered to indicate statistical significance. Statistical analysis was performed with the Statistical Package for Social Sciences software (SPSS version 23.0 for Windows).Data are presented as mean ± standard deviation for continuous variables. Discrete variables are presented as frequencies and percentages. Baseline characteristics were compared using the independent-samples ression) . The fol2, and infarct size 12 ± 11 g. In the patients randomized to CTO-PCI, the PCI was performed on day 5 ± 2 after primary PCI. Baseline CMR was performed 4 ± 2 days after primary PCI. Baseline GLS was available in 184 patients and GCS in 176 patients. Serial GLS measurements were available in 166 and serial GCS in 160 patients . Changes in strain parameters were also related to change in LVEF; however, change in LVEDV and infarct size showed poor correlation with change in global strain    Fig. . Howeverß − 0.40, 95% CI − 0.68 to − 0.12, p = 0.006), together with baseline LVEF, LVEDV, and presence of microvascular obstruction (MVO) (Table p = 0.009) (Supplement Table p < 0.001).Both GLS and GCS were univariate predictors for LVEF at 4-month follow-up. In multivariate analysis, GLS remained a significant predictor for functional outcome (4-month LVEF) (O) Table . During n = 160 patients). Segmental strain was significantly recovered from baseline to 4-month follow-up in the dysfunctional segments , p < 0.001; Table p = 0.50).There were 2560 segments available for serial segmental circumferential strain analysis . In multivariate analysis, segmental strain was an independent predictor for regional wall thickening recovery, incremental to baseline wall thickening and infarct . Of the dysfunctional segments, 74% was viable (TEI < 50%) and MVO was present in 13%. In a multivariate analysis, baseline wall thickening, segmental strain, and infarct (TEI) were all statistically significantly related; however, based on the This is the first study evaluating the recovery and value of global and segmental myocardial strains in STEMI patients with a concurrent CTO, and the first to determine the effect of CTO-PCI on strain recovery. The main findings are the following: (1) Global and segmental strains improved over time, with no significant treatment effect of CTO-PCI; (2) GLS was a significant predictor for functional outcome incremental to infarct size, LV function, and clinical parameters; however, for mortality, infarct size remained the strongest predictor; and (3) segmental strain is incremental to TEI in predicting regional wall thickening recovery, especially in the CTO territory.Although strain significantly recovered at follow-up, we did not find a beneficial effect of CTO-PCI compared with no-CTO PCI on this recovery, which is consistent with the main EXPLORE trial results. FT-CMR strain has substantial clinical potential to be of diagnostic and prognostic value. Global strain measurements are highly reproducible with good to excellent intra- and inter-reproducibility and analysis appears not to be influenced by the level of training , 18. HowFor mortality, infarct size remained the strongest predictor. Previous reports regarding the prognostic value of global strain have been conflicting. In a study with 470 ischemic and non-ischemic cardiomyopathy patients, GLS was a strong predictor for mortality incremental to LVEF and infarct size . In 74 SSegmental strain significantly recovered at follow-up. Yet, there was no effect of CTO-PCI, compared with no-CTO PCI, on global nor on segmental strain recovery. However, we have previously shown that wall thickening significantly improves after CTO-PCI compared with no-CTO PCI in the dysfunctional CTO territory . AlthougWe did find that segmental strain was a strong predictor for wall thickening recovery, incremental to infarct, especially in the dysfunctional CTO territory. This finding is consistent with previous data: in 45 STEMI patients, segmental strain was incremental to infarct and MVO in predicting recovery of wall thickening . HoweverIn our high-risk patient population, new risk stratification parameters may be relevant to adequately select patients for CTO revascularization. None of the randomized CTO trails conducted showed a beneficial effect of CTO-PCI on clinical outcome nor on LVF, although ischemia and viability testing prior to inclusion were not mandated. It remains to be determined what the optimal patient selection threshold for CTO revascularization is and whether optimal selection will indeed lead to improved outcomes. Further studies are needed to investigate the true value of (stress) FT-CMR strain in clinical evaluation and whether it can be used as a diagnostic and prognostic tool to select patients that might benefit from PCI.There are several limitations applicable to this study. Unfortunately, not all CMRs were suitable for strain analysis and not all patients underwent baseline CMR. Furthermore, infarct data was not available in all patients and only 4% of the dysfunctional segments in the CTO territory were non-viable (TEI > 50%), making sample size relatively small and underpowered. Infarct size was probably decreased by the presence of collaterals, which were present in > 90% of the patients. As with all randomized trials, patient selection has occurred. The mortality rate was relatively low in our study cohort with the risk of overfitting the model and EXPLORE was not powered for clinical outcomes.Global and segmental myocardial strains, measured by FT-CMR, improved significantly over time in STEMI patients with a concurrent CTO, with no beneficial effect of CTO-PCI. GLS was an independent predictor for functional recovery, incremental to infarct size, LVEF, and clinical parameters. Although GCS predicted mortality, infarct size remained the strongest predictor. Segmental circumferential strain was an independent predictor for regional LV recovery in the dysfunctional CTO territory.ESM 1(DOC 1386 kb)ESM 2(PPTX 44711 kb)


Takotsubo cardiomyopathy is characterized by chest symptoms, electrocardiographic changes, and new regional wall motion abnormality in the apical segment of the left ventricle in the absence of obstructive coronary artery disease. Particularly, apical ballooning is broadly recognized as the classic form of takotsubo cardiomyopathy. Although the prognosis of most patients with takotsubo cardiomyopathy is generally favorable, complications associated with the morphological features of transient apical ballooning are not uncommon.We describe two cases of transient complications in postmenopausal patients with takotsubo cardiomyopathy. Intraventricular thrombus was observed in Asian patient 1, and severe mitral regurgitation was observed in Asian patient 2. These complications were confirmed by transthoracic echocardiography immediately after typical takotsubo cardiomyopathy with apical ballooning was diagnosed. Anticoagulant therapy with heparin and warfarin was continued for 1 week in patient 1. After the therapy, complete resolution of the apical thrombus and recovery of systolic function of the left ventricle was observed by follow-up transthoracic echocardiography. In patient 2, transthoracic echocardiography indicated significant mitral regurgitation, which was caused by left ventricular tethering of the anterior mitral leaflet rather than left ventricular outflow tract obstruction or systolic anterior motion. Because the hemodynamic stability in patient 2 had been preserved, she was managed with conservative treatment. After approximately 1 month, follow-up transthoracic echocardiography revealed that mitral regurgitation had almost disappeared with complete resolution of left ventricular wall motion abnormalities.The presented cases indicated that important complications, such as intraventricular thrombus and severe mitral regurgitation, are associated with takotsubo cardiomyopathy in the acute phase. Because these complications are risk factors for developing a thromboembolic event or heart failure and/or pulmonary edema, timely and accurate identification of these complications is critical to achieving optimal clinical outcomes in patients with takotsubo cardiomyopathy. Takotsubo cardiomyopathy (TCM), also known as stress cardiomyopathy or broken heart syndrome, is typically characterized by the morphological features of transient apical ballooning of the left ventricle. It occurs more often in postmenopausal women and is frequently associated with emotional, psychological, or physical stress preceding the presentation . CommonlRecently, TCM has been recognized worldwide, and reports on patients with TCM have been increasing, but there are only a few reports on thrombosis and valvular disease complicated with TCM. We report two cases of patients with TCM with transient complications, such as formation of an intraventricular thrombus and severe mitral valve regurgitation (MR).2). Her blood pressure was 178/86 mmHg, pulse 99 beats/minute (regular), and respiratory rate of 18/minute with oxygen saturation of 96% on room air. Her body temperature was 37.2 °C. Her physiological examination revealed no abnormalities, with the exception of arm pain. She had alert consciousness, and her neurological examination result was normal. On the day following admission, she experienced sudden onset of chest pain and palpitations associated with cold sweats and shivering. On physical examination, her heart rate, blood pressure level, and oxygen saturation were 118 beats/minute, 119/75 mmHg, and 97%, respectively. She was afebrile, and neither heart murmurs nor abnormal breath sounds were heard. Her abdominal examination showed no notable findings. Edema was not detected in either lower limb. Her consciousness level was clear, and no apparent neurological deficit was observed. An electrocardiogram (ECG) showed ST-segment elevations in II, III, aVF, and V3–V6 leads. Her creatine kinase (CK) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were 519 U/L  and 5435 pg/ml (< 125 pg/ml), respectively. Her qualitative troponin T was positive. Two-dimensional TTE using speckle tracking  with an automated function imaging technique provided with the commercial imaging analysis software  showed akinesis of the middle and apical segments of the left ventricle with typical apical ballooning and hyperkinesis of the basal segments  and lansoprazole 15 mg). She had no smoking habit or alcohol consumption. She also had no family history or employment history of note. On examination at the time of admission, her height and weight were 1.45 m and 43.0 kg, respectively , 119/84 mmHg, and 100%, respectively. Her body temperature was 36.2 °C. A grade 3/6 holosystolic murmur could be heard at the apical heart area as the loudest, whereas friction rubs and gallops were not heard. The rest of the examinations, including respiration and abdomen, were unremarkable. Edema was not detected in either lower limb. She was awake, alert, and oriented. Her neurological examination on admission did not reveal any motor or sensory deficit, and her cranial nerves were normal. ECG showed ST-segment elevation in V5 and V6 leads. The main laboratory findings were as follows: troponin T 1.04 μg/ml , CK 543 mg/dl (43–165 mg/dl), and NT-proBNP 2441 pg/ml (< 125 pg/ml). TTE showed apical LV wall akinesis with basal hyperkinesis and severe MR. She underwent an emergent cardiac catheterization. Coronary angiography showed no obstruction, and left ventriculography revealed an ejection fraction (EF) of 67.8%, severe localized apical hypokinesis with hyperkinesis of the basal segment, and grade 3 severe MR. Further two-dimensional echocardiographic examination with speckle tracking on the admission day demonstrated severe LV apical systolic dysfunction   or myocardial infarction (4.6%) [et al. reported a case of a patient with TCM-related LV protruding thrombus requiring surgery [The incidence of cardiac thrombus due to TCM is reported to be 2.2–8.0% , 6. In mgulation . Furthergulation . These mn (4.6%) . A reporn (4.6%) . The thrn (4.6%) . A muraln (4.6%) . Althoug surgery .Significant (moderate-to-severe or severe) acute MR is another potentially serious complication, accounting for 8–19% of patients with TCM , 17. In There are no randomized clinical trials to establish specific treatment of TCM. In patients with mild TCM, no treatment or a short course of limited medical therapy may be sufficient. Renin-angiotensin-aldosterone system blockers may be considered during the period when regional wall motion abnormality is present in patients with heart failure with reduced EF. Administration of β-blockers would be reasonable when coronary spasm is not suspected as the etiology of TCM, because catecholamine is often excessive. When the patients with TCM have severe congestive heart failure or cardiogenic shock, it is important to assess whether significant MR or LVOT obstruction is associated with their condition. Cardiogenic shock, which occurs in 4–20% of patients with TCM, may be exacerbated by right ventricular involvement, LVOT obstruction, or acute MR . In patiIntracardiac thrombus and severe MR may be causes of embolic events and cardiogenic shock, respectively, which may lead to poor clinical outcomes. Therefore, detection and diagnosis of the presence of complications, especially in the acute phase, and appropriate treatment of the complications are necessary for patients with TCM.


Non-ischaemic dilated cardiomyopathy (DCM) occurs in 1 in 2500 individuals in the general population and is associated with considerable morbidity and mortality. Studies involving large numbers of unselected DCM patients have led to consensus guidelines recommending implantable cardioverter-defibrillator (ICD) implantation for protection against sudden cardiac death (SCD) in those with LVEF ≤35%. The purpose of this article is to review the literature for other potential markers including serological, electrocardiographic, echocardiographic, cardiac magnetic resonance, ambulatory ECG and genetic data, to highlight other potential markers that may optimise risk stratification for SCD in this cohort and thereby allow a more personalized approach to ICD-implantation.FLNC) and RBM20 which may be associated with higher rates of ventricular arrhythmia.Recent studies including the Danish study to assess the efficacy of ICDs in patients with non-ischemic systolic heart failure on mortality (DANISH) trial have questioned the benefits of ICD implantation in this group of patients with no changes in all-cause mortality. Recent pooled cohorts of patients with genetic DCM and in particular in those with Lamin A/C (LMNA) mutations have identified patients at increased risk of SCD and allowed the creation of algorithms to prognosticate SCD risk in mutation carriers. Furthermore, genetic testing has identified other DCM-causing genes including filamin C (To date, risk-stratification for SCD has been hampered by the utilisation of heterogenous subsets of idiopathic DCM patients and by use of static risk models where predictions are based on a single time point with a lack of consideration of disease progression. The current focus of personalised risk-stratification for SCD is shifting towards better characterisation of underlying DCM aetiology and the development of multi-parametric risk-stratification models that incorporate time-dependent disease characteristics and novel biomarkers. Non-ischaemic dilated cardiomyopathy (DCM) occurs in 1 in 2500 individuals in the general population . This isWhile most data suggest that implantable cardioverter defibrillators (ICD) prevent SCD and lower mortality in DCM cohorts by up to 31% , only 20Given these limitations of LVEF as a solitary risk marker in DCM, alternative biochemical, clinical and imaging risk markers have been sought. As yet, most studies are based on retrospective or observational registry data, but a number of potential candidates for risk predictors are emerging and discussed below.Troponin T (TnT) and NT-proBNP (BNP) are serum biomarkers that indicate the severity of the heart failure phenotype and/or myocardial injury and are correlated with prognosis , 11. RaiC-reactive protein (CRP) is a marker of inflammation, and significantly higher levels have been shown to be present in DCM patients dying within 5 years of hospitalization compared to survivors . In thosSerum levels of pro-inflammatory cytokines, including IL-1, are significantly increased in patients with heart failure , 18. IntSeveral studies have analysed the association of various electrocardiographic markers with the risk of SCD in DCM including QRS duration, QRS fragmentation, microvolt T-wave alternans and QRS-T angle. In a detailed meta-analysis of markers of SCD, both depolarization and repolarization ECG abnormalities were more common in DCM patients with SCD. Fragmented QRS complexes, T-wave alternans, abnormal signal-averaged ECG (SAECG) and prolonged QRS duration were all significantly associated with SCD with decreasing magnitudes of relative risk .QRS duration is a relatively easy, reproducible marker and has been shown to be a significant predictor of cardiovascular mortality, SCD and appropriate ICD shock in patients with DCM . In a stMicrovolt T-wave alternans (TWA) is defined as a beat-to-beat alternation of T wave amplitude and reflects spatiotemporal repolarization heterogeneity which acts as a substrate for arrhythmia. TWA was initially thought to be a promising independent marker of SCD in patients with DCM –31, but 24-hour Holter monitoring demonstrates non-sustained ventricular tachycardia (NSVT) in 40-60% of patients and polymorphic ventricular ectopy (VE) in up to 90% of DCM patients . Data frSustained ventricular tachycardia (VT) occurs in under 5% of DCM patients and is a risk factor for SCD. Inducibility of VT on electrophysiology study (EPS) has been suggested as valuable for risk stratification in previous consensus guidelines, but most data suggest that EPS discriminate poorly between high and low-risk patients with respect to SCD. In the MADIT II study, inducibility of ventricular arrhythmia on EPS was associated with an increased likelihood of VT but not of VF and was not a good predictor of a composite endpoint of VT/VF , 40. In Echocardiography is the most common imaging modality used to assess the severity of LVEF and thereby provide prognostic data in patients with DCM. Other echocardiographic parameters have also been considered including LV dimension, atrial size and in a study of 710 DCM patients, mitral regurgitation on baseline TTE was an important predictor of VA .Newer echocardiographic technologies such a speckle tracking, have been suggested to provide incremental improvements in SCD stratification. For example, global longitudinal strain (GLS) is a marker of myocardial regional contractility and an impaired GLS may reflect myocardial fibrosis . GLS canMechanical dispersion is the standard deviation between different myocardial segments of the time to peak negative strain. In a small study of 94 patients with DCM, mechanical dispersion was higher in patients that experienced arrhythmic events compared to those that didn’t (98±43ms vs 56±18ms) and was an independent predictor of arrhythmias  .CMR provides a reproducible assessment of LVEF and LV volumes, and with the administration of gadolinium contrast, data on myocardial scarring. T1 and T2 sequences are also used to quantify interstitial fibrosis and myocardial oedema.Late gadolinium enhancement (LGE) is present in up to 38% of DCM patients . MyocardSeveral studies have demonstrated an association between fibrosis and SCD in patients with DCM , 46–50. Despite these extensive data, there are no randomised controlled trial (RCT) data to confirm the impact of these findings with respect to LGE and there is no conclusive evidence to demonstrate that patients with severe LVSD and without fibrosis are not at-risk of SCD. Other issues include a lack of standardization in the methodology, quantification and analysis of LGE as well as a lack of appreciable threshold of fibrosis over which arrhythmic risk elevates .Some patients with DCM undergo endomyocardial biopsy (EMB) particularly if there are concerns of inflammatory conditions such as active myocarditis. EMB data may be utilised to provide data on the quantification of interstitial myocardial fibrosis in patients with DCM. This however is limited by procedural risks of EMB as well as by sampling error which may be particularly relevant with non-homogenous distributions of fibrosis. Native pre-contrast T1 times and extra-cellular volume fractions on cardiac magnetic resonance may reflect the degree of interstitial fibrosis in patients with DCM and offer a non-invasive method to quantify myocardial collagen composition , 53, 54.Patients with heart failure often have altered sympathetic activation which predisposes to progressive ventricular dysfunction and arrhythmias and is likely to contribute to an increased risk of SCD . MyocardA family history of sudden cardiac death is associated with SCD events in heart failure patients  and moreTTN mutations [TTN mutation carriers, but progressive heart failure predominates. In contrast, other disease genes appear to be associated with a much higher risk of SCD. Specific examples include the following:The number of disease-causing genes is considerable, but emerging data suggest that truncating mutations in titin (TTNtv) are the commonest cause of genetic DCM, accounting for between 15-25% of cases . Patientutations , 66. ArrLMNA mutations account for as many as 10% of cases of genetic DCM and are associated with early atrial and ventricular arrhythmia, premature conduction disease, SCD and progression to ESHF resulting in death or heart transplantation (HTx) [LMNA mutations are associated with a high clinical penetrance by the age of 60 years and with considerable morbidity and mortality [LMNA mutation carriers followed up for a median of 43 months, 18% experienced malignant VA . This study identified the NSVT, male sex, non-missense mutations and LVEF <45% as risk factors for malignant VA [LMNA mutation carriers identified the same risk factors but also found 1st degree or higher AV block as a predictor [LMNA mutation carriers and that higher EF thresholds should be accepted for ICD implantation.on (HTx) –69. LMNAortality . In a stgnant VA . A more redictor . This stFLNC account for up to 4% of DCM cases [FLNC mutations had a cardiac arrest with a mean age of 42±16 years and a mean LVEF of 39.6±12% [FLNC mutations are associated with a significant risk of VA events and lower thresholds for ICD implantation may need to be considered in this group.Truncating mutations in CM cases  and are 39.6±12% . Moreove39.6±12% . AlthougTTN) and calcium/calmodulin dependent kinase II delta (CAMK2D). A recent study of carriers of RBM20 mutations identified an association with an arrhythmogenic DCM with increased incidence of VA [RBM20 mutations had sustained VA compared to 5% of TTN mutation carriers despite similar LVEF. In another multicentre study of 74 RBM20 mutation carriers, there was a considerable family history of SCD (51%) and patients with RBM20 mutations were more likely to have NSVT (43% vs 11%) and sustained VT (25% vs 2%) than idiopathic DCM cohorts [The RBM20 splicing factor is involved in the splicing of Titin  and heart transplantation (18% vs 2%) compared to those that do not carry a PLN mutation. R14del carriers are also more likely to have a family history of SCD at <50 years (36% vs 16%) with a mean age of SCD at 37.7 years; SCD often being the index presentation at a young age [Mutations in the phospholamban gene are associated with an arrhythmogenic DCM characterised by low voltage ECG complexes and frequent ventricular arrhythmic events. The best characterised oung age .DSP gene are associated with ARVC but recent data suggest that they more typically cause a left-dominant arrhythmogenic cardiomyopathy. Variants in DSP are associated with left ventricular systolic dysfunction, myocardial fibrosis and ventricular arrhythmia [DSP mutations can develop sustained VT in the absence of severe LVSD and primary prevention ICD implantation is often considered in the presence of an abnormal LVEF [Mutations in the rhythmia . Importamal LVEF .SCN5A are associated with conduction disease and Brugada syndrome. Some mutations, including R222Q are associated with DCM, atrial arrhythmia, frequent premature ventricular complexes and SCD [SCN5A DCM cases [Mutations in  and SCD , 79. ArrCM cases . There aCM cases .Risk stratification for SCD in DCM is difficult and complex. Whilst SCD can be prevented by implantation of primary prevention ICDs, these devices come with their own risks.ICD implantation can be associated with short and long-term complications including device infection or erosion, psychological impact and a risk of inappropriate shock. This also includes the risk of device malfunction with lead failure and the need for regular generator changes over the patient’s lifetime –84. GiveAll RCTs for the prevention of SCD in DCM have focussed on LVEF as a stratifier of risk , 7. ConsMost recently, The DANISH trial demonstrated that ICD implantation in DCM (76% idiopathic) was not associated with a significant reduction in all-cause mortality compared to OMT  in spite of a reduction in SCD rates ••. PossiRisk stratification has been hampered by utilisation of heterogenous subsets of idiopathic DCM patients and a by a static risk assessment where predictions are based on a single time point with a lack of consideration of progression (deterioration or improvement) in the condition on OMT. The current focus is shifting towards better characterisation of the underlying aetiology of DCM and the development of multi-parametric risk-stratification models that incorporate time-dependent disease characteristics and novel biomarkers.


Careful monitoring of plasma cTnI concentration and an electrocardiogram could be supportive biomarkers, predicting the onset of lapatinib-induced cardiovascular adverse events.Cancer chemotherapies have improved prognosis in cancer patients, resulting in a large and rapidly increasing number of cancer survivors. “Onco-cardiology” or “cardio-oncology” is a new discipline for addressing the unanticipated cardiac side effects of newly developed cancer drugs. Lapatinib, a tyrosine kinase inhibitor suppressing the epidermal growth factor receptor and ErbB2, has been used in advanced or metastatic breast cancer treatment. Reportedly, lapatinib has induced cardiovascular adverse events including QT-interval prolongation and heart failure. However, they have not been predicted by preclinical studies. Hence, a new method to assess the tyrosine kinase inhibitor-induced adverse effects needs to be established. Here, we intravenously administered lapatinib to halothane-anaesthetised dogs, evaluating cardiohemodynamic, electrophysiological, and echocardiographic profiles for pharmacological safety assessments. We intravenously administered lapatinib to chronic atrioventricular block beagle dogs to assess its proarrhythmic potential. The therapeutic concentration of lapatinib significantly increased total peripheral vascular resistance, QT, QTc, monophasic action potential (MAP) However, their life after cancer is often hindered by unexpected adverse events resulting from anti-cancer therapy. For example, a certain type of tyrosine kinase inhibitors has yielded unanticipated cardiac adverse events in frequency and severity. A new discipline called “onco-cardiology” or “cardio-oncology”, aimed at monitoring the cardiovascular safety of antitumour therapies, has evolved over the past decade in the clinical setting. Although popularly perceived as a clinical discipline that brings oncologists and cardiologists working together, cardio-oncology is, in fact, a pharmacology-oriented translational discipline2. Generally, safety pharmacology studies are not carried out minutely in common anticancer drugs during preclinical studies, since this guideline describes that in the absence of a specific risk, the studies will not be called for to support clinical trials or for marketing2. On the contrary, evaluation of the adverse pharmacodynamic and/or pathophysiological effects of a drug, observed during clinical studies, is one of objectives of the safety pharmacology studies3. The implementation of precise safety pharmacology studies according to follow-up studies for the safety pharmacology core battery may alter the unexpected adverse events to expected ones, leading to contribute to provide a better quality of life in cancer survivors3.The ICH S9 guideline provides information for pharmaceuticals that are intended to treat cancer in patients with serious and life threatening malignancies4. This drug has been used in the treatment of patients with advanced or metastatic breast cancer who have received prior therapy including anthracyclines, taxane, and trastuzumab. Diarrhoea is one of the most common adverse events of lapatinib, but cardiotoxicity should be monitored as a side effect6. The overall incidence of cardiac adverse events with lapatinib has been reported to be 2.70% , including heart failure in patients with breast cancer and other HER2-positive cancers7. Importantly, the drug has been also reported to prolong QT interval in the clinical use7 and has been shown to inhibit the human ether-à-go-go-related gene (hERG) current in a concentration-dependent manner8. However, this potential for QT-interval prolongation has not been indicated in preclinical telemetry studies using dogs4. Lapatinib has slightly increased mean systolic, mean diastolic, and mean arterial pressure in telemetered dogs at single oral doses ≥150 mg/kg 6 to 14 h after dosing4. On the contrary, no significant changes in blood pressure have occurred in patients administered lapatinib4.Tyrosine kinase inhibitors have been widely used for the treatment of various types of cancers. Lapatinib is a tyrosine kinase inhibitor that suppresses both the epidermal growth factor receptor (EGFR or ErbB1) and ErbB2 (HER2), for the treating patients with advanced or metastatic breast cancer4. In addition, we evaluated some blood biochemical markers to predict its cardiotoxicities. These studies would be translational research to clarify the cardiovascular adverse events in clinical practice.To the best of knowledge, safety pharmacological assessments of lapatinib evaluating onco-cardiology have not been precisely investigated in non-clinical studies. There are no established methods to precisely predict the lapatinib-induced adverse effect. Hence, in this study, we simultaneously assessed the cardiohemodynamic electrophysiological, and echocardiographic profiles of lapatinib using the halothane-anaesthetised canine model. Furthermore, we assessed the proarrhythmic effects using the chronic atrioventricular block model in dogs. Notably, lapatinib binds to their ErbB2 with the similar potency of the human receptor based on sequence considerationsNo animals demonstrated any lethal ventricular arrhythmia or hemodynamic collapse, leading to the animals’ death during the experiment.P/dt, peak −dP/dt, and the left ventricular end-diastolic pressures (LVEDP) are summarised in Fig. The time courses of changes in the heart rate, mean blood pressure, cardiac output, total peripheral vascular resistance, peak + dThe time courses of changes in the electrocardiogram variables, atrio-His (AH) and His-ventricular (HV) intervals are summarised in Fig. 90 during sinus rhythm and the ventricular pacing at a cycle length of 300 and 400 ms, effective refractory period and terminal repolarization period during the ventricular pacing are summarised in Fig. 90(sinus), MAP90(CL300), MAP90(CL400), effective refractory period, and terminal repolarization period were 269 ± 12, 225 ± 8, 248 ± 9, 229 ± 10, and 19 ± 2 ms, respectively. Lapatinib significantly increased the MAP90(sinus) at 60 min, the MAP90(CL300) at 15 and 60 min and effective refractory period for 5–60 min after the high dose, respectively. No significant changes were detected in the other variables.The time courses of changes in the MAPThe effects of lapatinib on the variables of echocardiogram are summarised in Table The time courses of the plasma concentrations of lapatinib, cTnI, N-terminal pro-B-type natriuretic peptide (NT-proBNP), creatinine kinase (CK), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) are summarised in Fig. No electrocardiogram waveform changes or lethal ventricular tachyarrhythmias were observed during the experimental period.The time courses of the changes in the electrocardiogram variables and the number of surviving animals are summarised in Fig. Beat-to-beat analysis was performed in each animal to assess the extent of torsadogenic potential of lapatinib, as depicted in Fig. 90(sinus), MAP90(CL400), effective refractory period, but minimally altered the terminal repolarization period and beat-to-beat variability, suggesting that the proarrhythmic potential of lapatinib might not be serious to induce lethal ventricular arrhythmias.Contrary to expectations based on previously reported canine telemetric studies, the therapeutic dose of lapatinib significantly increased the QT interval, QTcV, MAPmax value of 2,430  ng/mL9. In addition, the value was approximately 2.4- to 3.0-fold higher when administered with food4. In the present study, lapatinib was intravenously administered in doses of 0.3 and 3 mg/kg over 10 min, providing the peak plasma concentrations of 697 ± 73 (1.2 µmol/L) for the low dose and 2,358 ± 424 ng/mL (4.1 µmol/L) for the high dose, respectively. Since the protein binding ratio of lapatinib to albumin and alpha-1 acid glycoprotein is greater than 99%, its free form concentrations can be roughly calculated as 6.97 and 23.58 ng/mL (12 and 41 nmol/L), respectively9. Reportedly, lapatinib inhibits the ErbB1 and ErbB2 receptors, the IC50 of which values were 9.2 and 10.8 nmol/L4. ErbB4 was inhibited with an IC50 of 360 nmol/L (36-fold higher than for ErbB2) and c-Src, a non-receptor tyrosine kinase, was inhibited with an IC50 of 3,500 nmol/L (300-fold higher). IC50 values for all other 16 tested enzymes were >1,000-fold higher than for ErbB1/ErbB24. Moreover, lapatinib has been reported to slightly inhibit IKs at 3,000 nmol/L, but hardly affect the INa, ICa and IK1 at this concentration8. The IC25 and IC50 values of the hERG current were reported to be 181 and 800 nmol/L, respectively8. Therefore, the doses of lapatinib used in this study would attain infra- to iso-therapeutic levels of the free plasma concentrations, which can inhibit the ErbB1 and ErbB2 receptors, but may hardly inhibit other protein tyrosine kinases, IKs, INa, ICa and IK1, although the hERG current can be modestly inhibited.The clinically recommended oral daily dose of lapatinib is 1,250 mg, producing a steady state geometric mean  CP/dt, peak −dP/dt, or the left ventricular end-diastolic pressures, whereas an increased total peripheral vascular resistance was observed at clinically equivalent concentrations. Three months of anti-ErbB2 treatment in humans have been reported to increase systolic and diastolic blood pressure, and plasma concentration of noradrenaline, whereas no change was observed in adrenaline or heart rate10. Furthermore, lapatinib has been known to slightly increase the blood pressure in telemetered dogs at the single oral doses of ≥150 mg/kg4. The inhibition of ErbB2 in the rostral ventrolateral medulla has been reported to induce hypertension, at least in part, by reducing NO synthesis and inhibiting γ-aminobutyric acid activity in rats11. Lapatinib reportedly distributes in the brain at about one-tenth the concentration of blood in rats12. In our present study, the concentrations of lapatinib in the brain could be estimated to overcome its IC50 values of ErbB2. The high dose of lapatinib increased the total peripheral vascular resistance, suggesting the centrally regulation of vascular tone via inhibition of the ErbB2 receptor. The continuous enhancement of the resistance could increase the strain on cardiac outputs, which might be a risk factor for inducing heart failure especially in the patients after treatments of anthracyclines or trastuzumab treatment.Lapatinib did not alter the heart rate, mean blood pressure, cardiac output, peak + d90(sinus), MAP90(CL400) and effective refractory period after the high dose, but did not alter the PR interval, QRS width or MAP90(CL300). Since the cycle length of the sinus rate was about 600 ms in this study, the prolongation patterns in each MAP90 were likely the reverse use-dependent manner, indicating that lapatinib might inhibit the hERG current. In the present study, the continuous prolongation of QT/QTcV interval and the late onset of prolongation of MAP90(sinus) and MAP90(CL400) could be partly explained by these previous findings8. Our suggestion might be pharmacokinetically supported by the previous report that lapatinib distributed to heart more than blood and decreased from heart slower than blood12. Diarrhoea is one of the most common and crucial adverse events of lapatinib, leading to electrolyte imbalances5. As hypokalemia may contribute to prolong QT/QTcV interval, attention should be paid to the proarrhythmic potential during lapatinib-induced diarrhoea.Lapatinib prolonged the QT/QTcV interval, MAP13. Sunitinib, a multi-targeted tyrosine kinase inhibitor, has been reported to induce systolic dysfunction in patients with an incidence of 3–8%14. In our previous non-clinical study, it significantly increased the end-diastolic pressure-volume relationship and prolonged the isovolumic relaxation time, in addition to decreasing the amplitude of the peak −dP/dt14. However, lapatinib minimally altered the echocardiogram variables in addition to peak + dP/dt and peak −dP/dt, suggesting that its acute cardiotoxicity potential for cardiac contractile performance might be relatively low.Furthermore, lapatinib is considerably less cardiotoxic than trastuzumab, but has been known to demonstrate symptomatic heart failure (0.2%) and asymptomatic cardiac events (1.4%)15. Lapatinib hardly altered the echocardiogram variables and NT-proBNP, suggesting that lapatinib may not damage the LV systolic and diastolic function during the acute phase. cTnI has known to act on myocardial contraction by regulating the calcium-dependent interaction of actin and myosin17. Although the mechanisms by which cTnI is released into the bloodstream are not fully understood, it is a more sensitive blood biochemical markers for cardiac injuries than CK, AST, and LDH17. It has been reported that the elevation of cTnI has been observed with the repeated administration of lapatinib combined with paclitaxel or trastuzumab18. Although the elevation of cTnI plasma concentration did not robustly predict chronic heart failure in the patients, it likely preceded changes in the LV ejection fraction18. It is noteworthy that the intravenous administration of lapatinib acutely increased the plasma concentration of cTnI in our study. Thus, close monitoring of cTnI may become a reliable marker in lapatinib-induced cardiotoxicity.Lapatinib increased the plasma concentration of cTnI without altering NT-proBNP, CK, AST, and LDH. Reportedly, NT-proBNP is a biomarker for reflecting left ventricular wall stress more closely than other ventricular parameters such as left ventricular (LV) ejection fraction, E/e’, and LV longitudinal strain in heart failure90(sinus), MAP90(CL400) and effective refractory period after the high dose in the halothane-anaesthetised model (Experiment 1). On the contrary, lapatinib hardly altered QTcF, long-term variability and short-term variability of repolarization in the chronic atrioventricular block dogs (Experiment 2). These discrepancies might be explained the reduced repolarization reserve due to halothane, through suppression of a slow component of the delayed rectifier K+ currents together with a rapid component one in the heart and by attenuating the autonomic tone19. Thus, these results suggest that lapatinib might not induce lethal ventricular arrhythmias.Lapatinib prolonged the QT/QTcV interval, MAPIn conclusion, the present precise safety pharmacology studies suggest that the therapeutic concentration of lapatinib prolonged QT interval and effective refractory period but did not induce torsade de pointes. These electrophysiological effects in our study may be well correlated with the clinical adverse effects of lapatinib, whereas the acute increase in the total peripheral vascular resistance might provide new insights in lapatinib-induced cardiotoxicity or its mechanism of action. Although the cardiotoxicity might not be so serious, careful monitoring of plasma cTnI concentration, in addition to an electrocardiogram could be a supportive biomarker to predict the onset of lapatinib-induced cardiovascular adverse events.In our present study, we observed three limitations. First, we did not assess the effects of repeated lapatinib administration on the cardiovascular systems. The lack of the impaired the diastolic function following the single administration of lapatinib dose not confirm the functional safety with repeated administration. Second, we did not assess the effects of lapatinib combined with anthracyclines, paclitaxel or trastuzumab, which are well known to possess cardiotoxicities. They could enhance or expose the toxicities of lapatinib. Third, we did not follow the plasma concentration of cTnI, NT-proBNP, CK, AST, or LDH after our experiment. Although cTnI was the most sensitive blood biochemical marker of the five to predict lapatinib-induced acute cardiotoxicities, we do not negate the possibility of the remaining markers to predict the delayed and/or chronic ones.These experiments were conducted at Faculty of Medicine, Toho University, where all of the authors concurrently belonged to from 2016 to 2018. All experiments were approved by the Toho University Animal Care and User Committee  and performed in accordance with the Guidelines for the Care and Use of Laboratory Animals of Toho University. The experiments were also in accordance with the Guidance for the Animals Experiment of the Japanese Society of Toxicology and the Japanese Pharmacological Society.Experiments were performed using 5 female beagle dogs weighing approximately 10 kg. The animals were obtained through Kitayama Labes Co., Ltd. . The dogs were housed in individual cages on a 12 h light (6:00–18:00)-dark (18:00–6:00) cycle. The ventilation provided a total air exchange rate of 10–15 times per hour. The room temperature was maintained at 23 ± 2 °C, and relative humidity was 50 ± 30%. Each dog was fed with 200 g/day of standard diet , and was allowed free access to tap water.14. The dogs were initially anaesthetised with thiopental sodium . After intubation with a cuffed endotracheal tube, 1% halothane vaporized with 100% oxygen was inhaled with a volume-limited ventilator . Tidal volume and respiratory rate were set at 20 mL/kg and 15 breaths/min, respectively.This experiment was basically carried out according to our previously reported method assessed for sunitinib® 4061119; St. Jude Medical Daig Division, Inc., Minnetonka, MN, USA) were inserted into the aorta through the right and left femoral arteries and the others were inserted into the inferior vena cava through the right and left femoral veins, respectively. To prevent blood clotting, heparin calcium (100 IU/kg) was intravenously administered through a flush line of the catheter sheath placed at the right femoral vein. A pig-tail catheter was placed at the left ventricle through the right femoral artery to measure the LV pressure, whereas the aortic pressure was measured at a space between the inside of the catheter sheath and outside of the pig-tail catheter through a flush line. The maximum upstroke and downstroke velocities of the LV pressure  were obtained during sinus rhythm to estimate its isovolumic contraction and active relaxation, respectively. In addition, the LV end-systolic and end-diastolic pressures were also measured during sinus rhythm, since the latter reflects the extent of the passive stiffness of the left ventricle20. A thermodilution catheter  was positioned at the right side of the heart through the right femoral vein. The cardiac output was measured with a standard thermodilution method by using a cardiac output computer . The total peripheral vascular resistance was calculated using the basic equation: total peripheral vascular resistance = mean blood pressure/cardiac output.Four clinically available catheter sheaths  was positioned at the non-coronary cusp of the aortic valve through the left femoral artery to obtain the His-bundle electrogram. A bidirectional steerable monophasic action potential (MAP) recording/pacing combination catheter  was positioned at the endocardium of the right ventricle through the left femoral vein to obtain MAP signals. The signals were amplified with a DC preamplifier . The duration of the MAP signals was measured as an interval, along a horizontal line corresponding to the diastolic baseline, from the MAP upstroke to the desired repolarization level. The duration (ms) at 90% repolarization level was defined as MAP90. The heart was electrically driven by using a cardiac stimulator  with the pacing electrodes of the combination catheter placed in the right ventricle. The stimulation pulses were rectangular in shape, 1–2 V of amplitude (approximately twice the threshold voltage), and of 1-ms duration. The MAP90 was measured during sinus rhythm (MAP90(sinus)) and at a pacing cycle length of 400 ms (MAP90(CL400)) and 300 ms (MAP90(CL300)). The ventricular effective refractory period was assessed with the programmed electrical stimulation. The pacing protocol on the assessment of the ventricular effective refractory period consisted of 5 beats of basic stimuli at a cycle length of 400 ms followed by an extra stimulus of various coupling intervals. Starting in late diastole, the coupling interval was shortened in 5 ms decrements until refractoriness occurred. Starting in late diastole, the coupling interval was shortened in 5 ms decrements until the additional stimulus could no longer elicit a response. The ventricular effective refractory period was defined as the shortest coupling interval that could produce a response. The duration of the terminal repolarization period of the ventricle, reflecting phase 3 repolarization of the action potential, was calculated by the difference between the MAP90 and ventricular effective refractory period at the same site, reflecting the extent of electrical vulnerability of the ventricular muscle22.The surface lead II electrocardiogram was obtained from the limb electrodes. Corrected QT interval (QTcV) was calculated with Van de Water’s formula: QTcV = QT−0.087 × (RR−1000)23. Estimated LV volume was calculated with the Teichholz formula: LV volume = 7 × (diameter)3/(2.4 + diameter)23. Ejection fraction and fractional shortening were calculated with following equations: ejection fraction = (LV end-diastolic volume − LV end-systolic volume)/LV end-diastolic volume × 100, and fractional shortening = (LV end-diastolic diameter − LV end-systolic diameter)/LV end-diastolic diameter × 100, respectively24. The LV end-systolic pressure-volume and end-diastolic pressure-volume relationships were calculated using the following equations: end-systolic pressure-volume relationship = LV end-systolic pressure/LV end-systolic volume, and end-diastolic pressure-volume relationship = LV end-diastolic pressure/LV end-diastolic volume, respectively. The peak velocities of early diastolic filling wave (E-wave) and atrial contraction wave (A-wave), in addition to the isovolumic relaxation time of LV, were measured with the recordings of transmitral flow velocity pattern. The peak velocity of early diastolic myocardial wave (E′-wave) was measured at the lateral mitral annulus with the tissue Doppler imaging, since diastolic dysfunction was reported to be firstly observed in the lateral wall25. The E/A and E/E′ ratios were calculated with the peak velocities of E-wave, A-wave and E′-wave.Two cardiologists certified by the Japanese Circulation Society performed the echocardiographic examinations by using the ultrasound system , equipped with a 2.7–8.0 MHz of wide-band frequency-fusion phase-array transducer. The LV end-diastolic diameter, end-systolic diameter, ejection fraction and fractional shortening were measured with the two-dimensional guided M-mode echocardiogramThe aortic and LV pressures, electrocardiogram, His bundle electrogram and MAP signals were monitored by using a polygraph system  and analysed with a real-time fully automatic data analysis system . Each electrocardiogram measurement, MAP as well as AH and HV intervals were determined based on the mean of three recordings of consecutive complexes. The cardiovascular variables were assessed in the following order. The electrocardiogram, His bundle electrogram, aortic and LV pressures and MAP signals were recorded during sinus rhythm. Next, the cardiac output was measured three times. Then, MAP signals were recorded during the ventricular pacing at a cycle length of 400 and 300 ms. Moreover, the ventricular effective refractory period was measured. All parameters described above were usually obtained within 1 min at each time point. Finally, the echocardiographic variables were obtained.After the basal control assessment, lapatinib in a low dose of 0.3 mg/kg was intravenously administered over 10 min, and cardiohemodynamic and electrophysiological parameters were assessed at 5, 10, 15, 20, and 30 min after the start of the infusion. Next, lapatinib at the high dose of 3 mg/kg was intravenously administered over 10 min, and the parameters were assessed at 5, 10, 15, 20, 30, 45, and 60 min after the start of the infusion. In addition, the echocardiographic study was performed at 30 min after the start of the low dose infusion, and at 30 and 60 min after the start of the high dose infusion.g for 15 min at 4 °C to obtain the plasma and stored at −80 °C to determine the plasma concentrations of lapatinib, cTnI, NT-proBNP, CK, AST, and LDH. The plasma concentration of lapatinib at 5, 10, and 15 min after the low dose, and 5, 10, 15, and 60 min after the high dose was measured by high-performance liquid chromatographic method followed by tandem mass spectrometry26 at Sumika Chemical Analysis Service, Ltd. . The blood biochemical markers were assayed at 30 min after the low dose, and 30 and 60 min after the high dose at LSI Medience Corporation  besides NT-proBNP. The plasma concentrations of cTnI were measured using a chemiluminescent micro-particle immunoassay, for which the lower detection limit was 0.02 ng/mL, calibration range was up to 50 mg/mL, and analytical sensitivity was 0.02 ng/mL at the 95% level of confidence in humans as well as dogs. NT-proBNP was assayed using Cardiopet® proBNP, for which the detection range was between 250 and 10,000 pmol/L, at IDEXX Laboratories, Inc. . Data were used from 3 animals for the statistical analysis of NT-proBNP, as two-fifth were the lower limit of quantitation during the experiment.A 2 mL volume of blood was drawn from the femoral artery at 10, 15, and 30 min after the low dose, and 10, 15, 30, and 60 min after the high dose. The blood samples were centrifuged at 1,500 27 and the catheter ablation technique for the atrioventricular node was used as previously described28. The dogs were anaesthetised with thiopental sodium  (n = 4). After intubation with a cuffed endotracheal tube, 100% oxygen was inhaled with a volume-limited ventilator . Tidal volume and respiratory rate were set at 20 mL/kg and 15 strokes/min, respectively. To prevent blood clotting, heparin calcium  was administered.This experiment was performed in accordance with our previously reported methodThe surface lead II electrocardiogram was continuously monitored with a polygraph system . A quadpolar electrodes catheter with a large tip of 4 mm  was inserted through the right femoral vein using the standard percutaneous technique under the sterile conditions and positioned around the tricuspid valve, observing the bipolar electrograms from the distal electrodes pair. The optimal site for the atrioventricular node ablation was based on the intracardiac electrogram, of which a very small His deflection was recorded, and the atrial/ventricular voltage ratio was > 2. The site was usually occurred at 1–2 cm proximal from the position, where the largest His bundle electrogram was recorded. The power source for atrioventricular node ablation was obtained using an electrosurgical generator , which delivers continuous unmodulated radiofrequency energy at a frequency of 500 kHz. After proper positioning, the radiofrequency energy of 20 W was delivered for 10 s, from the tip electrode to an indifferent patch electrode positioned on the animal’s back, which continued for 30 s if junctional rhythm was induced. The endpoint of this procedure was the development of a complete atrioventricular block with the onset of stable idioventricular escaped rhythm.1/3, in addition to their proarrhythmic effects, were assessed without anaesthesia. The ventricular rate, QT interval, and QTcF were expressed as the mean of 10 consecutive complexes. In this study, torsade de pointes was defined as a polymorphic ventricular tachycardia associated with QT-interval prolongation, consisting of 5 beats or more twisting QRS complexes around the baseline29.A Holter recording and analysis system  was used to record and analyse the electrocardiogram over 24 h. The effects of lapatinib on the ventricular rate, QT interval, and corrected QT calculated with the Fridericia’s formula: QTcF = QT/(RR/1000)19. About 2 h after the start of Holter recording, 3 mg/kg of lapatinib was intravenously infused over 10 min without anaesthesia. The electrocardiogram variables at 1 h before the drug administration were defined as the control, and the electrocardiogram was recorded for >20 h when lethal arrhythmia was not induced.Experiments were conducted at least 4 weeks after the induction of complete atrioventricular block. We have assessed the pro-arrhythmic effects of several drugs with a group size of 4–6, which has sufficient sensitivity and reliability to detect drug-induced torsade de pointesn versus QTn+1 were prepared for each of three analysis time-points. The mean orthogonal distance from the diagonal to the points of the Poincaré plot was determined as short-term variability (=∑|QTn+1 − QTn|/[30 × √2]). On the contrary, the mean distance to the mean of the parameter parallel to the diagonal of the Poincaré plot was determined as long-term variability (=∑|QTn+1 + QTn − 2QTmean|/[30 × √2]). These nomenclatures were adopted from investigations of heart rate variability in human beings30, which have been applied to the QT-interval analysis in normal dogs and chronic atrioventricular block dogs31.An electrocardiogram of 31 consecutive beats under the stable idioventricular automaticity without ectopic activity was adopted before, and at 1 and 21 h after the drug administration. When the QT interval was obscured by the P wave, we estimated the end of T wave by cancelling the component of the P wave from the electrocardiogram waveform on the screen. Poincaré plots with QT® 0.5 g for Injection, Mitsubishi-Tanabe Pharma, Osaka, Japan), halothane , heparin calcium , benzylpenicillin potassium  and streptomycin sulphate (Meiji Seika Pharma).Lapatinib  was dissolved in dimethylsulfoxide of 100 mg/mL (0.1 mg/µL). The solution was injected at a dose of 30 µL/kg to the experimental dogs. The other drugs used were thiopental sodium . The statistical significances within a parameter were evaluated by one-way repeated-measures analysis of variance (ANOVA) followed by Contrasts as a post-hoc test for mean values comparison. A p value < 0.05 was considered to be statistically significant.