Primary carnitine deficiency (PCD) not treated with L-Carnitine can lead to sudden cardiac death. To our knowledge, it is unknown if asymptomatic patients treated with L-Carnitine suffer from myocardial scarring and thus be at greater risk of potentially serious arrhythmia. Cardiac evaluation of function and myocardial scarring is non-invasively best supported by cardiac magnetic resonance imaging (CMR) with late gadolinium enhancement (LGE). The study included 36 PCD patients, 17 carriers and 17 healthy subjects. A CMR cine stack in the short-axis plane were acquired to evaluate left ventricle (LV) systolic and diastolic function and a similar LGE stack to evaluate myocardial scarring and replacement fibrosis. LV volumes and ejection fraction were not different between PCD patients, carriers and healthy subjects. However, LV mass was higher in PCD patients with the severe homozygous mutation, c.95 A > G . Among homozygous PCD patients there were two cases of unexplained myocardial scarring and this is in contrast to no myocardial scarring in any of the other study participants (p = 0.10). LV mass was increased in PCD patients. L-carnitine supplementation is essential in order to prevent potentially lethal cardiac arrhythmia and serious adverse cardiac remodeling. Patients homozygous for the PCD related c.95 A > G mutation in SLC22A5 have been shown to be especially vulnerable with regards to potentially lethal cardiac arrhythmia. This genotype is especially prevalent in the small island community of the Faroe Islands4. Cardiac fibrosis assessed by late gadolinium enhancement (LGE) with cardiac magnetic resonance (CMR) is positively correlated to ventricular tachyarrythmias and SCD in various cardiomyopathies7. Late gadolinium enhancement (LGE) with cardiac magnetic resonance (CMR) is a marker of myocardial fibrosis of any etiology8.Primary carnitine deficiency (PCD) not treated with L-Carnitine can lead to sudden cardiac death4.PCD is an autosomal recessive disorder of fatty acid oxidation caused by a dysfunctional organic carnitine (OCTN2) transporter. The transporter is highly expressed in myocardial cells and consequently attains a high plasma-myocardial gradient of carnitine. A dysfunctional OCTN2 transporter reduces this gradient because of a compromised myocardial carnitine transport as well as a result of low plasma carnitine concentration subsequent to excessive renal loss of carnitine. However, carnitine is a vital metabolite for the heart as it is necessary for the transfer of long-chain fatty acids across the inner mitochondrial membrane for beta-oxidation. Apart from an increased risk of SCD other major findings in PCD include cardiomyopathy in especially children as well as hepatic failure and the most common symptom fatigue. Patients are treated with daily oral L-carnitine supplementation to prevent development of complicationsAlthough PCD can cause lethal cardiac arrhythmia current treatment strategy does not include the use of an implantable cardioverter defibrillator (ICD) as primary prophylaxis. It is unknown if asymptomatic patients treated with L-Carnitine could still be susceptible to cardiac arrhythmia because of undiagnosed myocardial damage and fibrosis due to carnitine deficiency.The aim of this study was to evaluate and compare cardiac function and myocardial scarring as late gadolinium enhancement with CMR in PCD patients with carriers and healthy subjects in order to assess if current prophylactic treatment strategy should be reevaluated.SLC22A5. Seventeen carriers of a PCD related mutation in SLC22A5 and 17 healthy subjects were also included  were included in the present study. Thirty-six patients with two different PCD genotypes were included: 17 patients homozygous for the c.95 A > G mutation and 17 patients compound heterozygous for c.95 A > G and a risk-haplotype (RH) in The number of identified adult PCD patients homozygous for the c.95 A > G mutation alive in the Faroese population was 26 – of whom two had migrated, two had an implantable cardiac defibrillator (ICD) and therefore excluded, two patients declined to participate due to personal issues at the time and three patients suffered from claustrophobia.All PCD patients received daily oral L-carnitine supplementation and were monitored in an outpatient setting with regular blood carnitine measurements. Carriers of a PCD related mutation are not treated with L-carnitine.All participants were informed orally and in writing and gave informed written consent before participation. The Faroese Ethics Committee and the Data Protection Agency approved the study and the study was carried out in accordance with the Helsinki Declaration.Written consent to report individual patient data was obtained from participants if applicable.3. In a previous study, patients homozygous for the missense mutation c.95 A > G mutation in SLC22A5 were shown to have only a mean residual OCTN2 transporter activity of 4% of normal, while patients compound heterozygous for the c.95 A > G mutation and the risk-haplotype (RH) have an 18% mean residual OCTN2 transporter activity9. The PCD carriers included in the study were carriers of the c.95 A > G mutation and were in the previous study shown to have a mean residual OCTN2 transporter activity of 46% compared to individuals without PCD9.Patients were included from a nationwide screening program in the Faroe Islands. Individuals with blood levels of free carnitine below a lower cut-off level of 5 micromol/L were genetically tested for mutations related to PCD10. Stroke volume (SV) was end-diastolic volume (EDV) minus end-systolic volume (ESV). LV ejection fraction (LVEF) was SV divided by EDV (%). All volumes are presented as indexed to body surface area (BSA). Scar tissue was assessed using a delayed enhancement inversion-recovery sequence  volumes, mass, systolic and diastolic function and scar tissue. CMR was performed on a 1.5 T scanner  with a dedicated cardiac coil. LV volumes and mass were assessed using a steady-state free precession cine sequence . Multiple slices in both the short-axis and axial imaging planes were obtained covering the entire cardiac fossa. LV volumes were determined in the entire cardiac cycle  using semi-automated endocardial contour detection with papillary muscles included in myocardial mass. Based on identification of LV myocardium, the part of the basal slice belonging to the LV was included, and the LV outflow tract was included based on reference to the 3-chamber image11.CMR with steady-state, free-precession sequences is considered the gold standard of cardiac chamber volumes (17). CMR is the method of choice for quantification of scar tissue compared with single-photon emission computed tomography owing to superior reproducibility and spatial resolution (18–20). Intra- and inter-observer variability of LVEDV, LVESV, left atrial maximum volume has been tested by our group in another study. Intra- and interobserver variability was lower than 2.86% for all measurespost-hoc test. Correlation was evaluated with Spearman’s correlation coefficient. All CMR values were compared to published published 95% confidence interval12. P value (double-sided) <0.05 was considered significant. All statistical analyses were performed using R  and GraphPad Prism 6.0c .All continuous variables are reported as mean ± standard deviation (SD) and indexed to BSA (Mosteller´s formula) where appropriate. Binomial variables were expressed as numbers (%) and calculated differences between proportions with the χ² test. Normal distribution was tested visually on a histogram of the residuals and differences between group means or medians were assessed using ANOVA and post-hoc analyses using Tukey’s There were no differences between the groups of subjects with regards to age, sex, body mass index (BMI) and plasma L-carnitine Table . Mean agTwo c.95 A > G homozygous PCD patients had unexplained myocardial LGE Fig. . One patLVEDV, LVESV were not significantly different between groups, but LV myocardial mass p = 0.037) was higher in c.95 A > G homozygous PCD patients Table . Only on7 was higOur main finding was that PCD patients homozygous for the severe c.95 A > G mutation had significantly higher LV mass and LV wall thickness compared to the other groups – with two of them exhibiting signs of unexplained myocardial scarring 12.5%) 22. CMR is superior to echocardiography to evaluate cardiac mass and dimensions, which could explain our novel finding of significantly higher mean LV mass in patients homozygous for the c.95 A > G mutation compared to the other groups. It also underpins our assumption that the mentioned genotype is associated with the most pronounced liability to develop symptoms in the Faroese PCD patient cohort.We have previously shown, that the hearts of newly diagnosed adult PCD patients were within normal echocardiographic ranges with no signs of structural abnormalities or cardiac hypertrophy – the results were though not stratified with regards to genotype23. To our knowledge, the incidence of areas of LGE in a hitherto healthy PCD population has not been investigated. Hence, we included a healthy control population in this study of whom none had any areas of LGE (n = 17). Neither had any of the carriers (n = 17) or patients suffering from the less severe genotype c.95 A > G/RH (n = 17). Our finding of two patients with unexpected myocardial scarring is noteworthy and gives rise to important questions.We found unexplained myocardial scarring using LGE in two PCD patients homozygous for the c.95 A > G mutation. A previously published case report from the US also described areas of LGE in a patient with PCD who had been non-compliant with regards to L-carnitine supplementation7. A recent study in patients fulfilling the criteria for an implantable cardiac defibrillator (ICD) due to heart failure with reduced ejection fraction showed that patients with no areas of myocardial LGE on CMR were in a lower risk of VT/VF24. Myocardial scarring is thought to either induce or maintain ventricular arrhythmias in several ways: 1) scarring creates insulating barriers that form alterations in conduction in the fibrotic tissue, resulting in re-entrant wave fronts of excitation; 2) scarring can be considered as the origin or modulator of cardiac after-potentials that lead to triggered activity causing VT/VF; 3) oxidative and metabolic stress stimulate early after-depolarization; 4) in areas of myocardiac scarring the myocardium is less electrically connected and is hence more likely to initiate VT/VF (source-to-sink mismatches)29.The presence of LGE in patients with various cardiovascular diseases has been shown to predict adverse outcomes including ventricular tachycardia and ventricular fibrillation (VT/VF)The relationship between myocardial scarring and VT/VF raises the question – are PCD patients with signs of myocardial scarring in an increased risk of SCD even when they adhere to their recommended L-carnitine supplementation? Should these patients receive a primary prophylactic ICD to prevent SCD? The questions are very relevant in this group of patients, because the primary prophylactic treatment strategy was e.g. used in the before mentioned case from the US, where the patient was fitted with an ICD. However, it needs to be stated that the US patient case was non-compliant to medical therapy. Three Faroese patients have also previously received ICDs.Even though two of the 17 patients homozygous for the c.95 A > G mutation did have signs of myocardial scarring, our study indicates that it is not a very common finding, even in patients suffering from severe forms of PCD. Our experience gained during the last decade seems to indicate that the best way to prevent cardiac arrhythmia is treatment with L-carnitine supplementation as there have been no incidences of cardiac arrhythmia in Faroese PCD patients treated with L-carnitine. Adherence to the treatment has also proven to be very good in most Faroese patients, which has been verified by regular measurements of blood carnitine in all patients. PCD patients treated with L-carnitine in the Faroe Islands are thus not offered primary prevention with an ICD, instead they are, apart from being treated with L-carnitine, also closely monitored in an outpatient setting with regular blood tests and consultations with a clinical geneticist and cardiologist.30. In a number of disease states, diffuse fibrosis can be assessed by quantitative CMR relaxometry, incorporating T1 mapping with high reproducibility, however it was not possible in the present study to include T1 mapping sequences.Although LGE is useful for reproducible assessment of myocardial scarring and replacement fibrosis, it is limited in its accuracy in the assessment of diffuse fibrosis. First of all, with conventional LGE imaging sequences, signal intensity is expressed on an arbitrary scale that is different in every image, and no direct comparisons can be made; second, the late enhancement is defined through contrast from a healthy area to an area with increased extracellular volume area and hence scarring or diffuse fibrosis cannot be assessedSome PCD patients have unexplained myocardial scarring shown by LGE. A relation between myocardial scarring, metabolic and oxidative stress and SCD has been shown in the literature. Hence, it can be speculated, that the myocardial scarring in some PCD patients combined with an oxidative or metabolic stress can be the substrate of the increased risk of SCD in untreated patients with PCD. L-carnitine supplementation is essential in order to prevent potentially lethal cardiac arrhythmia.


Real-time image-guided LV lead implantation is feasible and may prove useful for achieving the optimal LV lead position.This study was performed to evaluate the feasibility of intra-procedural visualization of optimal pacing sites and image-guided left ventricular (LV) lead placement in cardiac resynchronization therapy (CRT). In fifteen patients , optimal pacing sites were identified pre-procedurally using cardiac imaging. Cardiac magnetic resonance (CMR) derived scar and dyssynchrony maps were created for all patients. In six patients the anatomy of the left phrenic nerve (LPN) and coronary sinus ostium was assessed via a computed tomography (CT) scan. By overlaying the CMR and CT dataset onto live fluoroscopy, aforementioned structures were visualized during LV lead implantation. In the first nine patients, the platform was tested, yet, no real-time image-guidance was implemented. In the last six patients real-time image-guided LV lead placement was successfully executed. CRT implant and fluoroscopy times were similar to previous procedures and all leads were placed close to the target area but away from scarred myocardium and the LPN. Patients that received real-time image-guided LV lead implantation were paced closer to the target area compared to patients that did not receive real-time image-guidance (8 mm [IQR 0–22] vs 26 mm [IQR 17–46],  Cardiac resynchronization therapy (CRT) has had a major beneficial effect on the treatment of patients with symptomatic heart failure, severe left ventricular (LV) dysfunction, and prolonged QRS duration. Nevertheless up to 30–45% of patients do not obtain a clinical or echocardiographic benefit from CRT . ImproviLV lead placement in or near an area of myocardial scar worsens outcomes –6, whileAforementioned challenges call for additional techniques that offer real-time visualization of optimal pacing sites during CRT device implantation. In the present study, we test the feasibility of a custom-made treatment-guidance platform , and patients with a contraindication for cardiac magnetic resonance (CMR), as well as patients with persistent atrial fibrillation, were excluded. All subjects gave written informed consent. The study was performed according to the Declaration of Helsinki and was approved by the local institutional review board and ethics committee.Fifteen patients with an indication for CRT according to the current ESC guidelines were prospectively enrolled . PatientIn this prospective feasibility study, LV target areas were determined on pre-procedurally acquired CMR and computed tomography (CT) scans using a custom-made platform, CARTBox . After LV target area identification, target areas were co-registered with live fluoroscopy during CRT implantations.specific tissue characteristics  (CSO) were identified on a pre-procedural CMR or CT scan. Based on the location of scar, delayed activation, and the LPN, a target area for LV lead delivery was chosen. Importantly, LV lead target area and tissue characteristics were fused with live fluoroscopic imaging, however they were not visible for the implanting cardiologist. Therefore, this group, in whom we performed treatment planning but no real-time image-guidance, is further mentioned as the non-target group. In step 4 (six patients) all aforementioned tissue characteristics were determined and displayed in conjunction with live fluoroscopy in the catheterization theatre during LV lead implantation. Thus enabling the implanting cardiologist to perform image-guided LV lead placement in a targeted treatment group (target group).The study was conducted in four steps to test the feasibility of the various features of CARTBox in a stepwise approach Fig. . During In all patients implantation characteristics  were collected together with electrical properties at the stimulation electrode , divided by QRS duration (QLV/QRS). Echocardiography was performed before and 6 months after implantation to determine the presence of LV reverse remodeling (defined as a ≥ 15% reduction in LV end-systolic volume).CMR was performed 1–7 days prior to CRT implantation in all patients, using a 1.5 T Philips Ingenia scanner . Gold standard late gadolinium enhancement (LGE) CMR scans were made to determine the size and the location of the myocardial scar. Short axis steady-state-free-precession cine images were made to determine areas of latest contraction, using feature tracking (CMR-FT) software . The settings during the CMR acquisitions were as follows. Cine: repetition time/echo time = 3.4 ms/1.7 ms, flip angle = 60°, voxel size = 1.67 × 1.67 mm, field of view = 32 × 32 cm, 192 × 192 matrix, 8 mm slice thickness, 30 phases/R–R interval, electrocardiogram-gated. LGE: repetition time/echo time = 3.2 ms/1.6 ms, flip angle = 15°, voxel size = 2.1 × 2.1 mm, field of view = 46 × 46 cm, 220 × 220 matrix, 8 mm slice thickness. Cine and LGE scans were made at the same positions with the same orientation.CT scans were performed 2–14 days prior to CRT implantation in nine patients for the identification of LPN and CSO. CT images were acquired using Turbo Flash in a Siemens Somatom Force 384 (2 × 192) row scanner . The CT protocol was optimized for visualization of contrast in the venous system using a double bolus technique to ensure opacification of the CSO. The first bolus of 60 ml of iodinated contrast medium  was administered at the start and the second bolus of 80 ml was injected after 40 s. Both boluses were injected at a rate of 6 ml/s into the basilic vein. CT scanning was triggered by using a bolus-tracking technique, with the region-of-interest placed in the descending aorta. Image acquisition started 11 s after the attenuation reached the predefined threshold of 200HU. Scanning time was approximately 0.25 s. The reference tube potential and tube current were set to 100 kV and 350mAs, respectively. Both were regulated by automatic potential and tube current programs (Care kV and Care dose 4D). Images were reconstructed with a 1.0 mm slice thickness and a 0.4 × 0.4 mm pixel spacing with a Bv40d reconstruction kernel.Image processing with CARTBox consisted of three steps Figs. , 3. The To start, the LV endo- and epicardium of the end-diastolic short axis CMR cine and LGE images were automatically segmented. The full width at half maximum method was used for the segmentation of myocardial scar on LGE images Fig. b 9]. Se. Se9]. SAfter CMR processing, the location of the CSO and course of the LPN were segmented manually from CT data. A board-certified cardiac radiologist (FMH) reviewed the results of the segmentation processes.In the second step, the implanting cardiologist selected the optimal area for LV lead delivery based on the course of the LPN and the 3D-CMR surface mesh containing scar transmurality [%] and contraction timing [ms] data , which allows 3D fusion of CMR and CT images with live fluoroscopy. After fusing the 3D-treatment datasets, 3D representations of the specific anatomical aspects  were visualized in conjunction with the fluoroscopy images by assigning a unique color for each anatomic structure Fig. . After rCRT device implantation was performed transvenously under local anesthesia. The right atrial and right ventricular leads were placed at conventional locations in the right atrium appendage and the right ventricular apicoseptal segment, respectively. After CS cannulation and coronary venous angiogram, a quadripolar LV lead was placed in one of the coronary veins overlying the LV free wall. After LV lead placement, all leads were connected to a CRT device.t-test for continuous variables with a Gaussian distribution. Pearson Chi-Square test was used for dichotomous variables. A p-value below 0.05 was considered significant.Statistical analysis was performed with SPSS . Each variable was tested for normality with a Shapiro–Wilk test. Continuous variables with a Gaussian distribution were described using mean, standard deviation and those with non-normal distribution were described with the median, interquartile range (IQR). Categorical data were described by an absolute number of occurrences and associated frequency (%). Differences between groups were assessed using nonparametric testing with Mann–Whitney U test for continuous data with non-normal distribution, and unpaired Student’s Fifteen patients, of whom baseline characteristics are provided in Table p = 0.07, and 27 ± 12 min, p = 0.17 respectively). Total radiation dose was 6758 ± 4201 cGycm2, the radiation dose of the pre-implantation and post-implantation 3D-rotational scan were 1188 ± 262 cGycm2 and 1313 ± 333 cGycm2  are displayed in Table In all patients that received real-time image guidance, LV leads were placed out of scar, away from the LPN and within, or in close proximity to the CMR defined target area. In three out of six patients the LV lead was implanted within the target segment, in the other three patients, the LV lead was placed adjacent to the target area. In patients from the target group, LV leads were placed significantly closer to the target area compared to patients from the non-target group , while distance of the LV lead to scar and the LPN did not differ between groups. The electrical properties in the target group did not vary from the non-target group and they were as follows: mean pacing thresholds: 0.65 ± 0.39V vs 0.58 ± 0.20V, paced QRS duration: 153 ± 22 ms versus 170 ± 22 ms, change in QRS duration from baseline: − 12 ± 13 ms versus − 9 ± 27 ms, and QLV: 150 ± 8 ms versus 130 ± 30 ms (QLV/QRS ratio 85 ± 10% vs 81 ± 16)  and CT scans (i.e. anatomy of the LPN and CSO) and were intra-procedurally fused with live fluoroscopic projections. This allowed the implanting cardiologist to place the LV lead out of scar, away from the LPN and closer to the CMR defined target area compared to CRT implantation without real-time image-guidance, while implantation duration and fluoroscopy time were not increased compared to historical controls.Previous work demonstrated significantly more LV reverse remodeling, lower cardiac mortality and fewer heart failure hospitalizations in patients paced from within a target segment with significant electrical or mechanical delay , 6, 14. In the present study, real-time image-guided LV lead implantation enabled placing the LV lead closer to the target segment compared to LV lead implantation without real-time image-guidance (treatment planning only). LV lead delivery within a pre-procedurally defined target segment, however, remains challenging. We were able to place three out of six LV leads within the CMR target segment using the overlay with fluoroscopy. The lack of a suitable coronary vein at the target site can be an important factor that may prevent LV lead delivery to a target segment. Additionally, in the present study, we did not adhere to the American Heart Association (AHA) 17-segment to determine LV lead target segments , but we This study was designed to demonstrate the feasibility of a novel treatment guidance platform for real-time visualization of optimal pacing sites during CRT implantation. Because the study was not designed or powered to demonstrate the superiority of real-time image-guided LV lead placement, no definite conclusions can be drawn regarding outcome data on implantation characteristics and end points. While, all patients that received real-time image-guided LV lead implantation were echocardiographic responder at follow up, other important factors probably have attributed to the high rate of reverse remodeling in patients from the target group. For instance, patients with persistent atrial fibrillation were excluded from study participation and patients from the target group had relatively favorable patient characteristics .2 (assuming an effective radiation area of 100 cm2) [2 [2) and the use of an iodinated contrast agent. Iodinated contrast agents may cause kidney dysfunction, especially in patients with pre-existing renal impairment. According to large, epidemiologically representative patient populations with chronic heart failure, about 10% of patients will have severe renal dysfunction (GFR < 30 ml min·1.73 m2) [Furthermore, we recognize that a relatively high radiation dose was used due to the additional 3D-rotational scans and pre-implantation CT imaging. The radiation dose of the CRT implantation without 3D-rotational scans was comparable to previous work , 21. In 100 cm2)  whereas,1.73 m2) . Therefo1.73 m2)  and the 1.73 m2) ) could iDespite the aforementioned challenges, and based on the superior patient outcomes of targeted LV lead placement, demonstrated by previous studies , 6, 15, Real-time image-guided LV lead placement by fusion of CMR- and CT-images with fluoroscopy images during CRT device delivery is feasible and endorses placing the LV lead closer to the target segment and out of scar compared to treatment planning only. Merging of target segments on to live fluoroscopy can be performed rapidly without prolongation of procedure time. Further investigation of this technology in clinical practice with larger patient cohorts is necessary to determine whether real-time image-guided LV lead delivery leads to improved patient outcomes and whether this approach is cost effective.


The past two decades have witnessed rapid and remarkable technical improvement of multidetector computed tomography (CT) in both image quality and diagnostic accuracy. These improvements include higher temporal resolution, high-definition and wider detectors, the introduction of dual-source and dual-energy scanners, and advanced postprocessing. Current new generation multidetector row (≥64 slices) CT systems allow an accurate and reliable assessment of both coronary epicardial stenosis and myocardial CT perfusion (CTP) imaging at rest and during pharmacologic stress in the same examination. This novel application makes CT the unique noninvasive “one-stop-shop” method for a comprehensive assessment of both anatomical coronary atherosclerosis and its physiological consequences. Myocardial CTP imaging can be performed with different approaches such as static arterial first-pass imaging, and dynamic CTP imaging, with their own advantages and disadvantages. Static CTP can be performed using single-energy or dual-energy CT, employing qualitative or semiquantitative analysis. In addition, dynamic CTP can obtain quantitative data of myocardial blood flow and coronary flow reserve. The purpose of this review was to summarize all available evidence about the emerging role of myocardial CTP to identify ischemia-associated lesions, focusing on technical considerations, clinical applications, strengths, limitations, and the more promising future fields of interest in the broad spectra of ischemic heart disease. Since the clinical introduction of multidetector computed tomography (CT) in the late 1990s , coronarIn consideration of its high sensitivity and negative predictive value (≥95%) for the detection of significant coronary stenosis , coronarThe EVINCI  study, a prospective multicenter European comparative effectiveness trial, has demonstrated that comprehensive assessment of anatomic CAD by CTA had a sensitivity of 91% and specificity of 92%, which were higher than functional test including myocardial perfusion imaging by either single photon emission computed tomography (SPECT) or positron emission tomography (PET) and ventricular wall motion imaging by either stress echocardiography or magnetic resonance imaging (MRI) . HoweverThe effects on clinical decision-making due to incorporation of CTA in the chest pain care pathway, jointly with its safety, are demonstrated in the SCOT-HEART  and in tCoronary CTA has also a prognostic value providing information on the total plaque burden, with a better outcome when there is no evidence of CAD and a worse prognosis in case of detection of coronary atherosclerosis, depending on its severity and extension –15.Moreover, it has the ability to detect nonobstructive non-flow-limiting CAD, helping to identify patients at risk of future cardiac events with more precision than functional testing .The actual limit of coronary CTA is the impossibility to assess the functional significance of coronary stenosis related to its moderate positive predictive value (about 50%) in detecting inducible myocardial ischemia –19.Physiological evaluation needs to be improved, because it influences the outcome of CAD more than its anatomical detection. In fact, studies using fractional flow reserve (FFR) have demonstrated that ischemia-guided coronary revascularization, especially percutaneous coronary intervention (PCI), is superior to angiography-guided strategy –23.In absence of myocardial ischemia, revascularization is associated with no symptomatic or prognostic benefit for patients, while it is effective in patients with moderate to severe ischemia  .The evidence of coronary stenosis, especially for luminal narrowing of 30-70%, is not predictive of inducible ischemia. Further functional test, such as SPECT, stress echocardiography, or stress perfusion MRI are needed to guide revascularization indication .Furthermore, a subanalysis of the EVINCI study has shown that, in patients at intermediate risk of CAD, hybrid imaging with CTA and SPECT allows noninvasive colocalization of myocardial perfusion defects and subtending coronary arteries, impacting clinical decision-making in almost one in every five subjects .In the last decades, we observed a rapid technological improvement, which led to a notable reduction of the scan time, motion artifacts, use of contrast agent, and radiation dose exposure, while yielding, at the same time, higher spatial and temporal resolution –27 whichThe purpose of this review was to summarize all available evidence about the emerging role of myocardial CTP in the assessment of the hemodynamic impact of coronary lesions, focusing on technical considerations, clinical applications, strengths, limitations, and the more promising future field of interest in the broad spectra of ischemic heart disease.In the classic ischemic cascade, perfusion abnormalities are the first to occur, before metabolic alterations, wall motion abnormalities, ECG changes, and symptoms.Stress tests evaluating myocardial perfusion have a higher sensitivity in detecting flow-limiting stenosis compared with other imaging modalities based on the induction of stress-induced wall motion abnormalities or ECG changes .Gould in 1974 was the first to investigate the relationship between luminal artery narrowing and the maximal hyperemic response .Thanks to coronary autoregulation, involving myogenic and metabolic mechanism, myocardial perfusion at rest is normal until the luminal diameter narrowing of a coronary artery exceeds 85-90%.However, in presence of coronary stenosis greater than 45% maximal coronary hyperemia induced by coronary arteriolar vasodilator leads to a progressive decrease in the hyperemic response .In this situation, exercise or pharmacological vasodilation of subepicardial resistance vessels results in a reduction in distal coronary pressure that redistributes flow away from the subendocardium, leading to a “transmural steal” phenomenon .Pharmacological stress agents are used to induce the hyperemic response in patients who cannot afford exercise test, that is, the preferred method to induce myocardial hyperemia.For stress CTP, the most used substances are adenosine and dipyridamole that lead to arteriolar vasodilation by both direct and endothelium-mediated mechanisms through stimulation of A2A receptors in the microvasculature. In the absence of microcirculatory dysfunction, the vasodilatory response is associated with a 3.5- to 4-fold increase in myocardial blood flow .Two intravenous (IV) lines are essential in CTP imaging for injection of the contrast media and of the vasodilator agent, respectively.Adenosine is a powerful, endogenous molecule with a nonselective activation of four distinct subtypes  receptors. Its infusion rate is 140 mcg/kg/min for 3 to 5 minutes with an infusion pump. Side effects could be AV block, peripheral vasodilation, and bronchospasm, but the most common are flushing, chest pain, dyspnea, dizziness, or nausea. Compared to dipyridamole, adenosine has a more rapid onset of action and a shorter half-life of 30 s; therefore most side effects resolve in a few seconds after discontinuation of the adenosine infusion.Dipyridamole increase intracellular and interstitial concentration of adenosine, indirectly leading to coronary arteriolar vasodilatation, and it does not require an IV pump for infusion as it can be applied manually at a slow rate in a dose of 0.56 mg/kg to 0.84 mg/kg over a 4- to 6-minute period. Due to its longer half-life of approximately 30 minutes, dipyridamole-stress patients may require administration of aminophylline (slow intravenous injection of 50 mg to 250 mg) for reversal of persistent symptoms , 34, 37.Recently, a new agent named regadenoson, an A2A selective agonist administered via a prefilled syringe in a single dose (400 mg) over 10 seconds, has been introduced as a pharmacologic stress vasodilator. It has a safer side effect profile in comparison to adenosine and dipyridamole, especially for patients with asthma or severe chronic obstructive pulmonary disease but it is limited by its cost and it is not widely available.Regadenoson has been shown to be accurate for the detection of obstructive CAD in nuclear perfusion imaging, stress echocardiography, and, more recently, stress CTP studies , 38, eveβ1-adrenergic receptors agonist, with mild effect on α1- and β2-receptors [μg/kg/min), dobutamine improves myocardial contractility and induces coronary vasodilation; at higher doses (20-40 μg/kg/min), it causes systematic vasodilation and serves as a positive chronotrope [Of note, the myocardial perfusion can be evaluated by dobutamine as well . The syneceptors . At low onotrope . At thesonotrope . In the onotrope , 40. Cononotrope , 40.Dobutamine is not the preferred pharmacological stressor in CTP imaging. However, as described by a recent case report, it may have a value to risk stratify patients with an anomalous coronary artery, since vasodilator stress imaging might not be sufficiently sensitive to identify dynamic coronary compression .The protocol of CTP imaging includes evaluation of myocardial perfusion during both rest (baseline) and stress (hyperemia) conditions and it is similar to other noninvasive imaging techniques such as stress cardiac MRI and nuclear imaging .CTP analysis is performed after administration of iodinated contrast through an antecubital IV access by imaging the left ventricular (LV) myocardium during the first pass of the contrast bolus. Iodinated contrast attenuates X-rays directly proportionally to iodine content in tissue; thus myocardial perfusion defects can be directly visualized as hypoattenuated or nonenhancing regions.Imaging during the early portion of first-pass circulation is critical, since after about 1 min a rapid wash-out of contrast agent due to diffusion to the extravascular space is expected .Contrast injection needs, at high flow rate, at least 5 mL/s for optimizing the strength of enhancement in the first-pass arterial phase .There are two protocols mostly used, named according to sequence of scan acquisitions: rest/stress or stress/rest. An interval of 10-15 minutes between the two sequences provides optimal contrast wash-out , 34.The rest/stress protocol uses the ability of coronary CTA to rule out obstructive CAD. CTP is performed only in the presence of anatomically defined CAD of intermediate or obstructive degree, avoiding further radiation and iodinated contrast exposure in absence of coronary artery stenosis. This protocol is limited by the cross-contamination of contrast in the stress phase and beta-blocker administrated before the rest acquisition, leading to underestimation of myocardial ischemia.The stress/rest protocol avoiding the risk of residual contrast media derived from the rest phase that may confound perfusion defects is optimized for the detection of myocardial ischemia.The contrast media contamination of the rest phase may decrease sensitivity for infarction , 34.Definitely, the best approach should be tailored on the patient's risk profile, reserving the rest/stress CTP for patients with low-to-intermediate pretest probability of CAD and stress/rest CTP for patients with high pretest probability of ischemia-associated lesions .Myocardial CTP imaging can be performed with different approaches such as static arterial first-pass imaging and dynamic time-resolved CTP imaging, with their own advantages and disadvantages.The static CTP imaging is based on acquisition of one single phase during the first-pass of the contrast agent. Certain technical challenges involving scan timing relative to maximum contrast enhancement and optimal contrast material delivery must be met .Generally, rest myocardial CTP imaging is derived from the coronary CTA examination.ECG-gating of coronary CTA or CTP can be retrospective (with prospective tube current modulation) , 43 but Prospectively ECG-triggered high-pitch spiral acquisition implemented with the second-generation 128-slice dual-source CT (DSCT) scanner allows the acquisition of the volumetric data of the heart in a single cardiac cycle with radiation exposure as low as 1 mSv , 46.Visual qualitative assessment is the analyzing method of static CTP. Thick multiplanar reconstructions of approximately 5 mm to 8 mm are usually recommended for myocardial perfusion analysis to improve the contrast-to-noise ratio.Myocardial contrast enhancement increases proportionally with iodine concentration, so perfusion defects appear as hypodense region with subendocardial or transmural distribution with respect to the normal myocardium.An integrated review of stress and rest images is important to characterize not only ischemic from nonischemic myocardium, but also viable versus nonviable myocardium by differentiating between fixed and inducible perfusion abnormalities .Hypoperfusion in stress with normal perfusion in rest underlines ischemia, whereas hypoperfusion in stress that persists with same extension in rest is indicative of necrosis . FurtherThe final step to the analysis of a CTA/CTP study is the match of perfusion defects with the anatomic localization of coronary epicardial stenosis, Automated software application provides analysis of semiquantitative metrics such as the transmural perfusion ratio (TPR), determined as the ratio of subendocardial to mean subepicardial contrast attenuation, which has been already initially validated for MRI perfusion. However, the accuracy of TPR may be significantly affected by motion and beam-hardening artifacts or by a thinning myocardial wall in the context of prior infarction .In conclusion, the patient specific ischemic burden may be determined in terms of volume of CT perfusion defect or percentage of ischemic myocardium relative to global myocardial volume .Dual-energy CT (DECT) myocardial perfusion imaging technology provides additional information about myocardial tissue composition compared with conventional single-energy computed tomography (SECT). Moreover, DECT improves limitations that are commonly present in SECT such as beam-hardening artifacts and blooming artifacts by using monochromatic image reconstruction .Based on the specific attenuation spectral characteristics of the different tissues when exposed to two different photon energy levels, DECT enables distinguishing the features of the tissue and evaluating the myocardial blood supply by mapping iodine distribution within the myocardium .Iodine map provides a measure of per-voxel iodine myocardial concentration expressed in mg/mL, which improves accuracy when compared to standard visual analysis , 49, 51,Different vendor-specific CT technologies have been developed to perform dual-energy acquisitions. Dual X-ray source system  is the most commonly used technology: there are two independent tubes paired with two detectors that simultaneously emit high (140-150 kV) and low (80-90-100 kV) energy levels .A second modality is based on single-source CT with rapid (about 0.25 ms) switching of tube voltage between 80 and 140 kV either in a single gantry rotation  or in sequential rotations  .The dual-layer (“sandwich”) detector  is an alternative approach made of two different materials able to differentiate between low and high energy photons, with the source operating at constant tube voltage; however this system is not yet available in routine clinical practice .Finally, the use of second- or third- generation DSCT scanners with high temporal resolution  could help discriminate between motion artifacts due to irregular or high heart rates and true perfusion defects, avoiding false positive findings .The only CT based technology that permits absolute quantification of myocardial perfusion is dynamic CTP imaging. It is based on repeated acquisition of the myocardial tissue during the first-pass contrast uptake to create time-attenuation curves (TACs) for the region of interest (ROI) , providiHemodynamic parameters, such as the myocardial blood flow (MBF), MBF ratio, and myocardial blood volume (MBV), and semiquantitative parameters such as the up-slope, peak enhancement, time to peak (TTP), tissue transit time (TTT), and area under the curve (AUC) are derived by dedicated algorithms of these TACs  , 55.Recently, the introduction of semiautomated three-dimensional software allowed a substantial reduction of the postprocessing phase, making the dynamic CTP more suited to routine clinical practice , Figure Whole-heart spatial coverage with appropriate temporal resolution is crucial to obtain multiple consecutive images at high heart rates .Dynamic datasets acquisition is currently performed with two different approaches. The first one provides the use of single-tube multidetector CT scanners with 256 or 320 detector rows, which cover the whole cardiac volume while the table is stationary . An alternative approach is second- and third-generation DSCT scanners, able to perform dynamic CTP imaging: by moving the scanner table back and forth (“shuttle mode”) between two scanning positions; it is possible to achieve a coverage of 73 or 105 mm, respectively, for the second- and third-generation DSCT scanners .In both cases, image acquisition is performed during the systolic phase of the cardiac cycle when apical-basal length is shorter and myocardial wall is at maximal thickness.Systolic phase length is relatively constant (about 200 ms) even when heart rate is high and irregular, so, images acquired in systole are less vitiated to beam-hardening artifacts because the amount of contrast medium needed for this phase is lower  .The obstacles to the clinical routine application of dynamic CTP are high radiation exposure, the relatively long breath-hold (approximately 30 sec) necessary for whole cardiac volume scanning, and spatial misalignment from two separated table positions when shuttle mode is used .The use of motion correction and beam-hardening correction algorithms could minimize artifacts, improving image quality and diagnostic accuracy .Advantages and disadvantages of static and dynamic CTP imaging are summarized in Many clinical studies and the first prospective multicenter trials have established the clinical feasibility and the diagnostic accuracy of static and dynamic CTP compared to SPECT, stress MRI, and/or invasive coronary angiography with and without fractional flow reserve (FFR), Tables 2A recent meta-analysis including 1188 patients in 19 studies showed that static CTP imaging in case of suspicion of known CAD, had a good agreement with SPECT and stress MRI perfusion with a sensitivity and specificity of 85% and 81%, respectively. When ICA was used as reference standard alone or in combination with SPECT or FFR, combined coronary CTA and CTP compared to coronary CTA alone significantly increased the specificity from 62% to 84% without significant decrease in sensitivity .Similar results were obtained in a meta-analysis of Takx et al.  evaluatiA prospective multicenter international trial, the CORE 320 study (n=381), has confirmed that static CTP imaging has a higher accuracy in comparison with SPECT in terms of significant CAD (≥ 50%) detection, using as reference ICA . The betThe increased sensitivity of CTP also derives from the more favorable extraction characteristics of iodinated contrast material allowing for a linear relationship between CT-derived metrics and myocardial blood flow. Conversely, Technetium-based tracers show a nonlinear net-tracer uptake in particular in the higher coronary flow range, causing the well-known-roll-off phenomenon .The CORE 320 studies have also proved that the specificity and overall accuracy of coronary CTA in detecting significant CAD (≥50%) defined by ICA and SPECT are significantly increased by the addition of CTP at both the patient and vessel levels , 63. ThiAnother recent randomized, multicenter, multivendor CTP study with regadenoson (n=110) by Cury et al. has shown that regadenoson-CTP imaging improved the diagnostic accuracy of coronary CTA from 69% to 85%, in particular by reducing the rate of false positive CTA results .Moreover, CTP showed a high sensitivity and specificity of 90% and 84%, respectively, for the detection of myocardial ischemia as defined by a reversible perfusion defect in ≥ 2 myocardial segments on SPECT, with an agreement rate of 87% .A considerable increase in diagnostic performance has also been largely proved when dual-energy myocardial CTP was coupled to coronary CTA, especially in terms of specificity, According to Meinel et al. the rest-stress protocol should be the first choice for evaluation of the myocardial blood supply in dual-energy CTP, with a sensitivity of 99%, specificity of 97%, positive predictive value (PPV) of 92%, and NPV of 100% using SPECT as reference of standard .The DECIDE-Gold, an ongoing prospective multicenter study, will define the diagnostic accuracy of dual-energy to detect hemodynamic significant CAD, comparing it to fractional flow reserve (FFR) as a reference standard .The available published data seem to suggest that static dual-energy and quantitative dynamic CTP imaging have a higher sensitivity, with respect to standard static monoenergetic CTP , 53, TabStress dynamic myocardial CTP has been initially studied in preclinical trials demonstrating a good correlation of CT-derived perfusion values with microsphere derived MBF data, histopathology, and invasive measurements of coronary blood flow and FFR, It is important to note that, as reported by a recent large animal study, dynamic CTP has a superior discriminatory power in detecting myocardial ischemia than static first-pass CTP, using fluorescent microspheres as a reference standard for MBF , 84. A sClinical researches have demonstrated that dynamic stress CTP may improve the PPV and specificity of coronary CTA alone , 78, espThis modality also enables the quantification of the absolute value of coronary flow reserve (CFR) calculated as the ratio of hyperemic to baseline MBF with a high degree of correlation to SPECT , 54.Moreover, dynamic CTP is useful in the global quantitative evaluation of left ventricular myocardial perfusion, especially in case of balanced ischemia caused by multivessel CAD .According to quantitative PET and CTP studies, the relative MBF (an absolute MBF-to-remote MBF ratio) leads to better detection of hemodynamically significant coronary stenosis than does the absolute MBF derived from dynamic CTP imaging, probably reducing the impact of microvascular resistance on myocardial perfusion –89.Semiquantitative parameters such as the TPR and myocardial reserve index (defined as the ratio of hyperemic and resting blood flow) have been suggested for static and dynamic myocardial CTP; however, they have a lower diagnostic accuracy than qualitative analysis by standard visual assessment , 57, 90.The CATCH-2 (CArdiac cT in the treatment of acute CHest pain 2), a prospective randomized controlled multicenter study published in 2017, has showed the usefulness of myocardial CTP assessment in addition to CTA, in patients with recent acute-onset chest pain when acute coronary syndrome had been excluded, and who had a clinical indication for outpatient noninvasive testing . CouplinFinally, as proved by a CATCH-trial substudy, myocardial CTP parameters predict mid-term clinical outcome in patients with recent acute-onset chest pain independently of the pretest probability of obstructive CAD . InteresDuring the last years, CT scanners with higher spatial resolution (approximately 1/3 of millimeter), temporal resolution (up to 66 ms), and wider detector array (up to 320-detector row) were developed, with a substantial improvement in CT performance and reduction of radiation exposure . FurtherConsequently, the contemporary estimated effective dose of coronary CTA and myocardial static CTP imaging will typically range between approximately 1.5 and 5.0 mSv, with an effective dose even to sub-millisievert levels for some exams , 93.However, numerous factors may influence the radiation dose, such as patient's characteristics , the type of CT equipment available, and the CT protocols used, which has to be tailored to the patient. Despite these promising innovations, the relatively high radiation exposure during dynamic CTP acquisitions remains a problem to be solved since it acquires a series of multiple low-dose acquisitions for the generation of TACs. Recent data have demonstrated that the average radiation exposure of dynamic CTP imaging is greatly depending on protocol optimization with an average value of 9.23 mSv (versus 5.93 mSv for static CTP) , which iHowever, Hubbard et al. validated a low-dose dynamic CTP technique based on a first-pass analysis model by using only 2 volume scans as compared with standard protocol based on multiple acquisitions in an animal model, showing good correlation with invasive FFR at different stenosis severity reaching overall effective radiation doses of 2.64 mSv .So current efforts are directed towards further reducing radiation exposure while maintaining a high diagnostic performance. In this regard, the use of recent technical innovations, including the low voltages (70 kV to 80 kV) acquisition, automated tube current modulation, and iterative reconstruction, seems to be able to achieve this ambitious goal .Many noninvasive techniques can perform an evaluation of myocardial perfusion, including SPECT, stress MRI, stress echocardiography, and positron emission tomography (PET) . NuclearPET is the gold standard for absolute quantification of myocardial perfusion particularly when 13N-ammonia is used and may be superior to SPECT in spatial resolution, image quality, and diagnostic accuracy . HoweverThese observations have fueled the pursuit of hybrid imaging strategies in which radionuclide myocardial perfusion imaging is combined with coronary CTA. While promising, this approach has some important disadvantages including higher radiation doses and elevated costs .Moreover, important SPECT limitations are the underestimation of the true extent of disease in patients with multivessel CAD and the photon attenuation artifacts typically due to breasts in women and diaphragm in men .MRI is the most versatile imaging modality: it can be used for morphology, function, viability, and quantitative myocardial perfusion assessment . Stress Stress echocardiography is a well-established, real-time imaging modality with advantages including lack of radiation exposure, versatility, and affordability. Dobutamine stress echocardiography could provide information about ischemic abnormal ventricular wall motion but this modality is lower than dobutamine stress MRI in terms of specificity (87.5% versus 72.9%), negative predictive value (80.8% versus 67.3%), and overall diagnostic accuracy (80.4% versus 72%) .The introduction of ultrasound contrast agents (microbubbles) has optimized the detection of RWMA and has enabled simultaneous assessment of left ventricular perfusion and viability, improving the sensitivity of the technique .According to a large multicenter prospective trial, myocardial contrast echocardiography (MCE) has higher sensitivity but lower specificity compared to SPECT for CAD evaluation . The supAlthough functional information provided by any of these techniques is well-validated and extremely useful, none of them provide a comprehensive anatomical-functional evaluation within the same study. Currently, myocardial CTP imaging is the only noninvasive modality that allows quantifying coronary stenosis and determining its functional relevance, rendering it a potential “one-stop-shop” method for the diagnosis and global management of patients with ischemic heart disease .Moreover, the imaging matrix of 512 × 512 pixels with an isotropic high spatial resolution (approximately 0.3 mm) of CTP is superior to nuclear imaging and enables evaluation of transmural differences in myocardial blood flow .Moreover, CTP imaging using the iodinated contrast agent does not suffer of the nonlinear relationship between myocardial signal intensity and gadolinium contrast concentration, which might affect the accuracy of quantitative analysis of MBF in MRI perfusion imaging .Finally, the wide availability of modern CT scanners makes CTP more accessible compared with other noninvasive tools, such as MRI or PET imaging .Advantages and disadvantages of functional imaging with echo, SPECT, MRI, and CTP imaging are reported in CT) using computational fluid dynamics has been clinically validated [Recently, a new technique to allow for noninvasive calculation of FFR based on conventional coronary CTA data  will compare the diagnostic performance of an FFRCT-guided strategy to stress CTP for the detection of functionally significant CAD, using invasive FFR as the reference standard .The current evidence suggests that myocardial CTP imaging improves diagnostic accuracy of coronary CTA alone mainly by reducing the number of false positive findings, even when compared with invasive FFR.With respect to this issue, an integration of both anatomical and physiological assessment of CAD may be a more robust “gatekeeper” to ICA by increasing the diagnostic accuracy while maintaining higher sensitivity compared to anatomical assessment alone. This may be particularly useful in difficult-to-interpret situations, such as in patients with coronary stents and heavily calcified coronary arteries in which blooming artifacts can hamper lumen visualization and correct stenosis measurements. Accordingly, recent studies have shown that stress CTP improves diagnostic performance in patients with a high Agatston calcium score  or coronThe utility of hemodynamic assessment by the integration of CTP and coronary CTA may have a potential role in stratifying cardiovascular risk and in the decision-making for the optimal medical intervention, although this potential role warrants further investigation.Furthermore, in line with PET imaging, dynamic CTP imaging offers the ability to obtain quantitative data of hemodynamic parameters (such as MBF and MBV) and the assessment of absolute CFR. The combination of coronary CTA and dynamic myocardial CTP makes CT a very promising technique to evaluate patients with microvascular dysfunction because it not only reveals the absence of demonstrable obstructive CAD but also provides data about CFR, the current gold standard for clinically assessing microvascular function.Quantification of hemodynamic parameters may be particularly useful for evaluation of specific patient population, such as patients with multivessel CAD, extensive nonobstructive CAD, hypertension, and diabetes mellitus .When global myocardial ischemia exists due to multivessel CAD, it may be difficult to achieve an accurate diagnosis with the qualitative analysis method by static CTP. Conversely, MBF analysis may be able to identify multivessel disease and predict the extent of ischemia more accurately than static CTP imaging , 53.The ability to quantify absolute MBF with dynamic stress CTP imaging permits identification of patients in whom the relative regional distribution of contrast agent may appear normal because of a balanced reduction of blood flow. Moreover, in patients with diffuse nonobstructive epicardial disease but no significant stenosis, the combination of plaque analysis by coronary CTA and CFR assessment derived by stress/rest dynamic CTP imaging may be helpful in identifying hemodynamic relevant coronary plaques, although not yet obstructive, and to avoid ascribing patient's symptoms to microvascular disease . In factFurthermore, MBF analysis might also be advantageous in monitoring disease progression or perfusion changes in response to therapy such as for PET and MRI imaging , 115, alHowever, important considerations have to be highlighted when interpreting quantitative measurements of dynamic CTP. A substantial underestimation of absolute MBF from dynamic CTP has been reported, with a significant influence of CT-derived MBF by temporal sampling rate , 117. ThFinally, it is well-known that all iodinated contrast agents have an immediate and direct vasodilatory effect . All theMoreover, the reported optimal MBF cutoff values for the differentiation of normal and ischemic myocardium varied considerably between dynamic CTP studies, ranging from 75 mL/100 mL/min to 103.1 mL/100 mL/min with a dual-source CT scanner and as high as 164 mL/100 mL/min using a 256-slices CT scanner , 34. ThiMoreover, numerous individual factors such as age, gender, race, BMI, presence and severity of CAD, the status of the microvasculature, individual adaptive vasodilator responsiveness, and/or the presence of collateral flow may affect MBF , 87, 118Accordingly, considerable regional heterogeneity of the myocardial perfusion across coronary territories has been demonstrated in healthy and low-risk subjects , 119.Large inter- and intraindividual differences in MBF distribution are already known from PET and MRI studies , 34. TheHowever, a major limit of dynamic CTP is the higher dose profile respect to static CTP due to the time-resolved acquisition of multiple phases.Furthermore, CTP imaging may be affected by several artifacts, such as partial volume, beam hardening, breathing, and motion artifacts. In particular, the patient's breathing motion poses a major challenge for dynamic CTP, which requires a long acquisition time of approximately 30 s. Furthermore, the sequence “shuttle mode” implemented with the second-generation dual-source CT scanner to dynamically cover the entire left ventricle myocardium may be a source of motion artifact influencing the estimation of MBF derived from the TACs. Beam-hardening artifacts arise from the polychromatic nature of the X-rays in the CT acquisitions and the presence of high-density iodine contrast agent in the heart chambers, which results in a hypoattenuated shadowing artifact . Areas aFurthermore, some of these artifacts may be partially attenuated by well-validated beam hardening and motion correction algorithms implemented with latest CT scanner technology , 34.Moreover, in most of the CTP studies, anti-ischemic drugs such as beta-blockers have not been withheld prior to stress testing; this may negatively affect the accuracy of CTP by decreasing the severity and the extent of myocardial perfusion defects. However, it is expected that the diagnostic performance of CTP imaging performed in patients without background medications could be even higher than reported.Finally, other limits are the broad spectrum of clinical characteristics of the studied populations and the difficult to standardize the CTP imaging due to the heterogeneity of scanner manufacturers, acquisition protocols, stress protocols, image analysis algorithms, and postprocessing parameters.In addition, no large-scale multicenter studies have demonstrated the clinical value of CTP imaging. Further researches with larger sample size and improved standardization of CTP imaging technique are warranted.Current evidence suggests that adding CTP imaging is a safe and powerful tool to improve the accuracy and the positive predictive value of coronary CTA alone because it not only provides anatomic information concerning luminal stenosis, plaque morphology, and total plaque burden but also provides data on myocardial tissue hemodynamics.Different acquisition protocols for CTP imaging are available, which can assess myocardial perfusion in a qualitative, semiquantitative, or quantitative manner, with their own advantages and disadvantages.In conclusion, coronary CTA combined with myocardial CTP imaging hold immense potential to evaluate almost every aspect of the broad spectra of ischemic heart disease with the possibility of guiding treatment decisions for a patient on an individual basis. Further researches with larger sample size should be designed and implemented to decide whether to adopt this new diagnostic modality in a routine clinical setting.Finally, prognostic studies are needed to assess if this combined approach will likely have substantial impact on treatment costs, patient management, and outcome. The time to challenge this hypothesis with randomized prospective trials has come.


Not all patients with angina pectoris have coronary artery stenosis. To facilitate the diagnosis of coronary artery disease (CAD), we sought to identify predictive factors of pulse spectrum analysis, which was developed by Wang and is one technique of modern pulse diagnosis. The patients suffered from chest pain and received cardiac catheterization to confirm the CAD diagnosis and Gensini score were recruited. Their pulse waves of radial artery were recorded. Then, by performing a fast Fourier transform, 10 amplitude values of frequency spectrum harmonics were obtained. Each harmonic amplitude was divided by the sum of all harmonic amplitude values, obtaining the relative percentages of 10 harmonics (C1-C10). Subsequently, multivariate logistic regression was conducted with two models and the areas under the receiver operating characteristic curves (ROC) of these 2 models were compared to see if combining the pulse diagnosis parameters with the risk factor of CAD can increase the prediction rate of CAD diagnosis. The predictive factors of CAD severity were analyzed by multivariate linear regression. A total of 83 participants were included; 63 were diagnosed CAD and 20 without CAD. In the CAD group, C1 was greater and C5 was lower than those of the non-CAD group. The CAD risk factors were put alone in Model 1 to perform the multivariate logistic regression analysis which had a prediction rate of 77.1%; while putting the C1 and C5 harmonics together with the risk factors into Model 2, the prediction rate increased to 80.7%. Finally, the area under ROC of Model 1 and Model 2 was 0.788 and 0.856, respectively. Furthermore, left C1, left C5, gender, and presence of hyperlipidemia were predictors of CAD severity. Therefore, pulse spectrum analysis may be a tool to facilitate CAD diagnosis before receiving cardiac catheterization. The harmonics C1 and C5 were favorable predictive indicators. Coronary artery disease (CAD) is a common cardiovascular disease. In recent years, the prevalence and mortality of CAD have been high  and are CAD is caused by atherosclerosis of the coronary arteries. Such arteries result in insufficient blood flow and oxygen supply and can cause myocardial ischemic changes which lead to a typical clinical manifestation of CAD: angina pectoris or chest pain. However, not all patients with angina pectoris or chest pain have CAD. A previous study indicated that 60% of patients who underwent cardiac catheterization for suspected CAD due to chest pain or angina pectoris did not have narrowed coronary arteries . In addiThe method “pulse spectrum analysis” was proposed by Wang based on the “resonance of organs with the heart” theory to explain the correlation between the pulse and human organs –8. The “The application of pulse spectrum analysis to assist the diagnosis of CAD has not been studied yet. This study aims to identify the characteristics of harmonics changes that aid CAD diagnosis in order to provide an evidence for further clinical diagnosis and preventive treatment.This prospective observational study was conducted from July 2011 to October 2012 in the cardiology ward of a medical center  in Northern Taiwan. Participant inclusion criteria for this study were (1) individuals who were 18 years of age or older, any gender, seeking treatment for chest pain or angina pectoris and (2) outpatients whose conditions were diagnosed by cardiologists as needing to be hospitalized to receive cardiac catheterization in order to confirm diagnosis and treatment. Exclusion criteria included acute myocardial infarction, cardiac arrhythmia, valvular heart disease, cancer, severe infection, pregnancy, severe mental illness, and individuals whose pulses could not be measured.The diagnosis and severity of CAD was evaluated by cardiologists according to photographic images of blood vessels taken during cardiac catheterization. If image results indicate that ≥ 1 blood vessel was ≥ 50% narrowed, CAD diagnosis was confirmed . SeveritThis study adopted the PDS-2010 Skylark Pulse Analysis System  to conduct pulse measurement. This single-probe measurement instrument was equipped with a high-fidelity pressure sensor, as well as X-Y-Z triaxial portable tracks used to locate the probe and apply vertical downward pressure in the measurement area to obtain the analog signal. Then, built-in programs were used to convert the analog signal into digital data and stored it in a computer.Participants were hospitalized from 15:00 to 17:00 the day before they received cardiac catheterization. After history-taking and related examinations were done, researchers explain the study procedure and consent form in detail to participants. Once participants understood and provided signed consent, researchers recorded their age, gender, height, weight, and comorbid diseases . Researchers then guided participants to an independent, quiet examination room with a room temperature maintained at 25–26°C.Measurements were performed by researcher using pulse diagnostic instruments after participants had rested quietly in the examination room for 10 minutes. Pulse measurements were performed on the radial arteries of the wrists on both arms, with the right arm followed by the left. In this study, the measurement position we selected was the most prominent position of the pulsation at the wrist radial artery, which corresponded to the styloid process of the radius. The graphical demonstration of the measurement position of the pulse is shown in Figures On the following day, cardiac catheterization was performed on participants at the radial artery (main section) or femoral artery. This was followed by coronary angiography to confirm the diagnosis of CAD and calculation of Gensini score. The coronary angiography was performed by the cardiologists, who were blind to the result of pulse measurements.Additionally, the following information was included recorded from medical chart: blood pressure values at the time of admission; and data such as fasting plasma glucose (FPG), total cholesterol, triglyceride (TG), and low density lipoprotein (LDL) cholesterol from laboratory examinations was arranged by cardiologists based on clinical diagnostic needs.In accordance with the method of pulse spectrum analysis developed by Wang, after we converted the digital data of the pulse measurements into a.txt file, we used LabVIEW 7  to perform a fast Fourier transform and obtained 10 amplitude values of frequency spectrum harmonics . Each harmonic amplitude was then divided by the sum of all harmonic amplitude values (A0), obtaining the relative percentages of the harmonics  or Cn = 100%  × (An/A0).Regarding demographic information for continuous variable, data are expressed as mean±SD and for categorical variables as numbers with corresponding percentages. The Chi-square test was used for categorical variables. Comparisons between CAD and non-CAD groups were performed via Mann–Whitney U test.In the analysis of pulse diagnosis parameters, to evaluate whether intragroup differences existed, we first conducted the Wilcoxon test on the relative percentages of the harmonics of both arms of the patients in each group. Then, the Mann–Whitney U test was used to evaluate the relative percentages differences of the harmonics between the CAD and non-CAD groups. Subsequently, multivariate logistic regression was conducted with two models: (Model 1) including only CAD risk factors, e.g., age, gender, body mass index (BMI), history of hypertension, diabetes, and hyperlipidemia; (Model 2) including the above CAD risk factors with the relative percentages of the harmonics with significant differences to assess the joint predictive effect on CAD diagnosis. Multivariate linear regression was also performed with the same variables along with the Gensini score to analyze which of these factors affected the severity of CAD. Finally, areas under the receiver operating characteristic curves (ROC) of Model 1 and Model 2 were compared to see if combining the pulse diagnosis parameters can increase the prediction rate of CAD diagnosis. P < 0.05 was regarded as statistically significant.Statistical calculations were performed using software package SPSS 20.0 . All comparisons were two-tailed;P < 0.01). There were no significant differences between the two groups in terms of gender, BMI, blood pressure values, the proportions with comorbid diseases of hypertension, diabetes, and hyperlipidemia  had statistical significance in Model 1, which had a prediction rate of 77.1% ( P < 0.05) and left C5 .Then, the CAD risk factors were put alone or together with the respective relative percentages of the harmonics  to perform the multivariate logistic regression analysis using an enter model, respectively, to realize the joint predictive of C1 and C5 on CAD diagnosis Tables  and 5. Aof 77.1% . While pIn order to explore the predictive factors of CAD severity, a multivariate linear regression analysis was performed with the Gensini score and the same factors  by an enter manner. The results revealed that the left C1, left C5, gender, and presence of hyperlipidemia were predictors of CAD severity . TherefoFinally, the area under ROC of Model 1 and Model 2 was 0.788 and 0.856, respectively .To the best of our knowledge, this was the first study to explore if pulse spectrum analysis can increase the prediction rate of CAD diagnosis in patients with chest pain or angina pectoris prior to cardiac catheterization. According to our findings, applying the pulse spectrum analysis together can receive a higher prediction rate for CAD diagnosis; specifically, the relative percentages of harmonics C1 and C5 are favorable predictive indicators. In patients diagnosed with CAD, there was a clear correlation when an increase in C1 and a decrease in C5 were observed.The pulse spectrum analysis method used in the present study was developed by Wang in accordance with organ resonance theory , 20. WanCAD is a heart disease that progresses from pathological changes in the coronary arteries. However, unless it involves severe heart damage owing to acute myocardial infarction, regular CAD develops slowly. In the development of CAD, changes in the circulation of other organs are interconnected or compensated and then redistributed. Therefore, we excluded patients with acute myocardial infarction from our observations and hoped that outpatients would demonstrate the aforementioned phenomenon; our results also indicated points of difference. When participants were diagnosed with CAD, C1 and C5 demonstrated significant changes, which indicated that the expected response had occurred in these two organ groups.Previous studies have been conducted using pulse spectrum analysis to observe patients with CAD; however, these studies have been scarce and had contrasting findings. In 1993, Chen observed pulse changes in 17 patients with acute myocardial infarction and measured their relative percentages of harmonics on the day that acute myocardial infarction occurred, 1 day after occurrence, 2 days after occurrence, and after creatine kinase (CK) had returned to a normal value. The results demonstrated that although C2 and C3 decreased during occurrence and increased in the following days, the other harmonics did not demonstrate differences before and after occurrence . This stOur result showed that C1 of the radial pulse wave could be a favorable predictive indicator for CAD diagnosis. The gradual increasing of C1 by aging was investigated by the harmonic based pulse waveform analysis method . Other sOur result showed that the C5 in the CAD group was lower than those of the non-CAD group; we proposed that the cerebral blood flow of the CAD group might be lower than the non-CAD group. According to the previous research, several studies have found evidence of a high prevalence of abnormalities in cerebral blood flow in patients with cardiac small-vessel disease . Pai et The left C1 and C5 change is more prominent compared to the right in our study. In human anatomy, the left subclavian artery and left common artery come directly off the aortic arch on the left side of the body, while on the right side they arise from the relatively short brachiocephalic artery when it bifurcates into the right subclavian artery and the right common carotid artery. Hence, the changes of left C1 and C5 are more prominent compared to the right side which might be related to the fact that the vibration resistance is smaller in the left side which is directly off the aortic arch than in the right side which is passing the bifurcation. According to the previous studies, the major wave modes in large arteries are the variation of the cross-sectional area of the artery driven by the pulsatile pressure force . Hence, The present study had some limitations. First, the sample size was small and the study was conducted in one medical center in Northern Taiwan. The participant population was simple, which may have caused sample selection bias. Therefore, if the findings of this study are to be generalized to all patients with CAD, a large-sample, multiregional, and multiunit study must be conducted for verification.Second, although the presence of CAD causes myocardial ischemia or necrosis, which leads to angina pectoris or death, patients without CAD may also have heart damage. Because no nuclear medicine cardiac scan record can be used to evaluate the degree of pathological changes in the heart, the correlation between pulse spectrum analysis results and these changes could not be directly compared.Third, in accordance with research ethics, invasive cardiac catheterization should not be performed on individuals without CAD. Therefore, the present study did not determine that asymptomatic and non-CAD patients could be compared. The findings are only suitable for the evaluation of symptomatic, suspected CAD patients.We explored the pulse spectrum analysis to determine that the relative percentages of C1 and C5 harmonics were favorable indicators which can increase the prediction rate of CAD diagnosis. This method can facilitate the CAD diagnosis before cardiac catheterization is undertaken to prevent the risk of myocardial infarction.


Aortic valve stenosis (AVS) represents a cluster of different phenotypes, considering gradient and flow pattern. Circulating micro RNAs may reflect specific pathophysiological processes and could be useful biomarkers to identify disease. We assessed 80 patients  with severe AVS. We performed bio-humoral evaluation  and 2D-echocardiography. Patients were classified according to ACC/AHA groups (D1-D3) and flow-gradient classification, considering normal/low flow, (NF/LF) and normal/high gradient, (NG/HG). Patients with reduced ejection fractionwere characterized by higher levels of miRNA1 (p = 0.003) and miRNA 133 (p = 0.03). LF condition was associated with higher levels of miRNA1 (p = 0.02) and miRNA21 (p = 0.02). Levels of miRNA21 were increased in patients with reduced Global longitudinal strain (p = 0.03). LF-HG and LF-LG showed higher levels of miRNA1 expression (p = 0.005). At one-year follow-up miRNA21 and miRNA29 levels resulted significant independent predictors of reverse remodeling and systolic function increase, respectively. Different phenotypes of AVS may express differential levels and types of miRNAs, which may retain a pathophysiological role in pro-hypertrophic and pro-fibrotic processes. It is due to a degenerative calcification process of the aortic cusps and, most commonly, it is a slowly progressive active process, associated with significant Left Ventricular (LV) pressure overload, inducing hypertrophy (LVH) and secondary myocardial fibrosis (MF)3. The key findings on transthoracic echocardiogram (TTE) are generally limited to the evaluation of thickening, calcification, reduced systolic opening of the valve leaflets and to flow-dependent parameters assessment (i.e. velocity and gradients), reflecting only the “valvular side” of the pathology4. This approach disregards the LV components  of the disease, resultingprone to diagnostic discrepancies6. Recently in literature, in fact, AVS has been depicted as a complex cluster of different phenotypes. Latest classifications are proposing a central role for indexed stroke volume (SVi) (“flow pattern”) to overcome diagnostic inconsistencies8. Withrespect to this, recent AHA/ACC guidelines for VHD patients management describe 3 distinct phenotypes for symptomatic severe (D) AVS: high gradient (D1); low-flow/low-gradient AVS with reduced Ejection Fraction (EF < 50%), or classical low flow AVS (D2); paradoxical low-flow/low-gradient AVS (D3) (EF > 50%)9. Another accredited classification for AVS is based on flow and gradient patterns, identifying 4 groups 11. Nowadays, cardiac imaging methods and novel biomarkers could provide an integrated assessment of the functional and structural aspects in AVS. In particular, Speckle Tracking Echocardiography (2D-STE) for the evaluation of myocardial deformation represents a more sensible tool to detect cardiac contractile function abnormalitiescompared to traditional parameters (i.e. EF)12. Regarding biomarkers, microRNAs (miRNAs) are small non-coding RNAs of about 21-nucleotides that regulate gene expression at a post-transcriptional level. About 2600 miRNAs have been identified in humans, possibly targeting about 30% of human genes14. Specific targets and biological roles have been assigned to onlyfew miRNAs, although almost every investigated process can be potentially regulated by miRNAs. The expression of many miRNAs shows tissue-specific or stage-specific patterns and their expression is associated with multiple pathological processes , which have non-negligible effects on the whole cardiovascular system14. The presence of circulating non-coding RNAs could be related to specific cardiovascular diseases and may represent a useful biomarker for different cardiovascular diseases identification. Considering the pathophysiological implications of AVS on myocardium (hypertrophy) and interstitium , we selected from literature a pool of microRNAs with an already proved and extensively demonstrated pro-fibrotic (miRNA21) or pro-hypertrophic  modulatory effect at pre-clinical (in vitro/tissue) and clinical level (circulating compart) on both myocardium and interstitium16.Aortic valve stenosis (AVS) involvesabout one-fourth of all patient with chronic valvular heart diseasethe relative expression of miRNA levels in different phenotypes of severe AVS;the association of miRNA levels with structural and functional echocardiographic variablesThe aim of our study was to evaluate:in a cohort of patients with severe symptomatic AVS evaluated for aortic valve replacement (AVR).Eighty patients with severe symptomatic AVS were prospectively enrolled at theAOUP Cardio-Angiology Unit - Pisaand screened between October 2015 and September 2016. For clinical symptoms, a NYHA Class > II was defined as overt heart failure (HF). Patients underwent laboratory analysis (including miRNA assays), and trans-thoracic echocardiography (standard and 2D-STE). The research was carried out according to the code of ethics of the World Medical Association (Declaration of Helsinki), informed consent was obtained, and the author’s institutional review board  approved the study. We excluded patients according to the following criteria: age < 18 years old; presence of major comorbidities ; not appropriate acoustic window; coronary/ischemic heart disease ; pregnancy; moderate or severe valvular disease; inability to sign consent; non-degenerative AVS; diskynetic septum . Follow-up data were collected at 12 months from AVR, using cardiologic visit (outpatient) and echocardiographic exam.17. Using standard M-mode/2D images at the parasternal long-axis views we calculated LV dimensions, includingend-diastolic/end-systolic LV diameters, end-diastolic thickness of the interventricular septum and posterior wall. Body surface area (BSA) was utilized to correct left ventricular mass calculation to derive mass index (LVMi). Both the apical 2- and 4-chamber views were considered to evaluate the LV end-diastolic and end-systolic volumes, andstandard Simpson’s rule was utilized to calculate EF. A spectral pulsed-wave Doppler analysis was performed to assess LV diastolic function, measuring early (E wave) and late (A wave) trans-mitral velocities, E/A ratio, and E wave deceleration time (DT). TDI was performed, adjusting gain and frame rate to optimize tissue characterization. The continuity equation was used to calculate the aortic valve area indexed (AVAi), and the modified Bernoulli equation allowedthe estimation of the maximum pressure gradient across the restrictive orifice. Mean trans-aortic pressure gradient (MG) derived from averaging the instantaneous gradients over the ejection period measured by continuous-wave Doppler recordings. We calculated also the valvulo-arterial impedance (ZVA) as a measurement of global LV afterload18. We used the color Doppler mode optimizing gain and Nyquist limit to evaluate the presence of regurgitant valve disease. The severity of valvular regurgitation was evaluated using a qualitative scale , according to the current guidelines17.We performed complete transthoracic exams using a heart-dedicated machine . Lateral decubitus position was the selectedpositionwhile data acquisition was performed with a matrix (M5S) probe at a depth of 16 cm in apical views  and the parasternal view (short - and long-axis views). All parameters were collected according to current recommendations17;Reduced EF was defined according to guidelines as EF < 50%19;Reduced global longitudinal strain (GLS), in accordance with prognostic studies, was defined as a value > −15.9%2 for women and 115 g/m2 for men20;Concentric Physiology was defined in presence of a Relative Wall Thickness (RWT) > 0.42, while relevant hypertrophy in presence of LVMi > 95 g/m11;Low transvalvular gradient was defined in presence of a MG < 40 mmHg2 7;Low flow condition was defined in presence of SVi < 35 ml/mVA was considered forvalues > 4.5 mmHg/ml/m2 18;Abnormal Z2/m2), D2  and D3 9;AHA/ACC classification: D1  NF/LG; 2) NF/HG; 3) LF/HG; 4) LF/LGIn our study population, we adopted the following classification criteria:21. Onlythe global longitudinal component of strainwas considered, using a dedicated software . To achieve this aim, we acquired standard 2D grey-scale images of the LV at conventional apical 2-,4-chamber and apical long-axis views. By tracking frame-to-frame natural acoustic markers, or speckles, equally distributed within the myocardial wall, 2D-STE represents an angle-independent technology, allowingmyocardial deformation analysis. The percentage change in myocardial length relative to the initial length, according to the strain Lagrangian formula, expresses myocardial strain in percentage. Analysing temporal variation of myocardial strain, we are able to calculate the strain rate that represents a measure of deformation rate. The longitudinal deformation consists in motion from mitral annulus to the apex in the apical views and may be negative (shortening) or positive (lengthening). We traced manually the endocardial contour at the end-systolic frame. Thenthe software, automatically, traced a concentric region of interest (ROI), including the entire myocardial wall. We verified the myocardial tracking, and we adjusted the ROI to optimize the tracking, where needed. Dividing each LV image into 6 segments, we performed a global and segmental strain analysis. A random sample of 10 patients was re-analysed by 2 independent observers. The intraclass correlation coefficient (ICC) and its 95% confidence intervals (CIs) were calculated to evaluate inter- and intra-observer reproducibility of 2D-STE. We obtained a good intra-observer and inter-observer repeatability (ICCs > 0.80).We used 2D-STE to asses LV GLS, according to current standardsStandard left heart catheterization was performed before AVR in 60 patients, in addition to coronary angiography. Invasive end-diastolic pressure , peak-to-peak gradient, and semi-quantitative aortic regurgitation were evaluated.We collected peripheral blood samples in specific tubes (PAXgene Blood RNA Tube), designed for immediate stabilization of peripheral blood RNA . Blood samples were collected and frozen at −80 °C within 2 hours after blood test. Frozen samples were equilibrated at room temperature for 2 hours before processing. RNA was isolated using the PreAnalytiXPAXgene miRNA isolation kit according to the manufacturer’s protocol. We estimated the quantity of RNAusing 2 µl of undiluted RNA solution anda Qubit 2.0 Fluorometer (Life Technologies). The resultsranged from 50 to 500 ng/µl of RNA. miRNAs were reverse transcribed from 500 ng of total extracted RNA sample using the miScript II RT Kit (QIAGEN). miRNA expression analysis was performed three times using 1 µl of cDNA as a template for real-time PCR with the miScript SYBR Green PCR Kit (QIAGEN) and the miScript Primer Assays ) according to manufacturer’s instructions on the CFX96 Real Time system c1000 thermal cycler (BIORAD). Data analysis was performed using the Bio-Rad CFX Manager Software v3.1. miRNA21, miRNA1, miRNA133 and miRNA29 expression was calculated using SNORD96 expression level as reference and the relative normalized expression ∆∆Cq formula. The number of technical replicates used for miRNA21, miRNA1, miRNA133 and miRNA29 was 3. We reported normalized expression levels respective to a housekeeping gene.All miRNA expression analyses were adjusted for estimated glomerular filtration rate (eGFR) values.see Supplementary Material and Table for details), in order to avoid the potential confounder effect, among others, of circulating blood cells, limiting cardiac specificity of miRNAs here tested, we validated circulating whole blood vs plasmatic compart by mean of linear regression analysis, also calculating inter-rater correlation coefficients (ICC). In the present paper we did not report a correlation between miRNAs expression levels and circulating blood cells.In 38 subjects (47.5%)  where assessed as appropriate. ANOVA or Kruskal-Wallis test were used to evaluate distribution of miRNA levels in different classification categories, with appropriate post-hoc corrections for interactions. For discrimination of patients with reduced SVi we used a c-statistic approach to derive the miRNA value with the best combination of sensitivity and specificity. Multivariate, stepwise regression analysis was used to identify predictors of reverse remodeling (Model 1) and systolic function recovery (Model 2). In the text we considered GLS in absolute value in order to preserve the statistical meaning of regression analysis (direct/inverse correlation/association). The threshold for statistical significance was p < 0.05. The following statistic package was used: Medcalc 12.7 .Table In Table We observed 14% of patients (n = 11) with reduced EF. Circulating miRNA21 showed inverse correlation with GLS in absolute value  and a direct correlation with E/e′ , as well as a reduction in peak trans-valvular velocity . A significant reverse remodeling was also observed . No significant increase in EF was reported , while GLS significantly improved from baseline . A significant correlation between Delta AVAi and Delta GLS was found . In a multivariate stepwise regression model (Table 2 = 0.89), while, in another model (Table 2 = 0.58). No significant gender differences were monitored during follow-up data.Follow-up data were available in 75 subjects (94% of cases). Thirty patients underwent surgical valve replacement , while 50 (62.5%) underwent percutaneous procedure. After an average follow-up of 15 ± 3 months, no major procedural complications nor long-term cardio-vascular events were noted. An increase in AVAi was observed 10. Several papers recently reported the determinant prognostic role of SVi, as a strong indicator of functional and flow conditions: reduced SVi is associated with advanced ventricular remodeling condition and a poor outcome23. Furthermore, LV response in terms of hypertrophy and fibrosis is peculiar in patients with AVS, because several factors play different roles at different levels and in different stages of the disease24. Current knowledge allows us to assert that miRNAs might represent important regulators of valvular disease development. Available data suggest that distinct miRNAs are dysregulated in AVS, supporting different underlying pathophysiological mechanisms. miRNA21 is up-regulated in cardiomyocytes during the fibrotic process; indeed, both myocardial and circulating levels of miRNA21 are significantly higher in patients with AVS compared to controls, correlating with MG and fibrosis. Previous data from our group also showed how miRNA21 manifested both in interstitial tissueand myocytes, with the fibrous tissue representing the site of major expression27. In this study, miRNA21 levels are associated with an impaired myocardial deformation, evaluated by GLS, and a reduced SVi, together with altered diastolic function and increased non-invasively-estimated filling pressure. Both miRNA29 and miRNA133 are modulators of fibrotic and hypertrophic processes and may reflect these 2 coexisting conditions also in AVS, potentially identifying an advanced or rapidly progressing valvular disease. In details, miRNA29 family is down-regulated in fibroblasts during myocardial fibrosis while it is up-regulated in myocardial hypertrophy; miRNA133 is down-regulated in cardiomyocytes during myocardial fibrosis and hypertrophy development. Combiningthe analysis of these modulators together with clinical parameters, it has been possible to predict LV mass normalization at one year after AVR30. Indeed, in our study miRNA29 and miRNA133 levels were significantly associated with some of the principal pro-fibrotic conditions (e.g. inverse correlation with eGFR and age), leading to impaired myocardial deformation and increased filling pressures. Interestingly, miRNA29 showed a differential distribution according to ACC/AHA stages of Valvular AS, with significantly higher levels in D2 patients (i.e. low-flow/low-gradient). Previous findingsdemonstratedboth LVH and advanced systolic compromise (namely EF reduction) represent relevant triggers for miRNA133 release31. We confirmed these data in our study, showing miRNA133 levels significantly increased in patients with reduced EF and advanced LVH. We focusedalso on miRNA1, described as down-regulated in cardiomyocytes during myocardial hypertrophic process33. In our population, miRNA1 levels increased in presence of reduced SVi and EF, with a significant differential distribution in 4-group flow-gradient classification (with higher levels in LF/HG and LF/LG groups). These findings further emphasize the link between the hypertrophic response and the impaired LV flow and function, proposing miRNA1 as a reliable index of flow condition and ventricular function, especially in AVS. Finally, according to literature, we reported a reduction of LV mass during follow-up (reverse remodeling) and an increase in longitudinal systolic function (GLS)34. Interestingly, in our regression models, baseline miRNA 21 and 29 levels resulted predictors of mass reduction, as previously shown30, and systolic function increase, assessed in terms of GLS, respectively. Then, we can speculate that the available evidence baseline miRNA levels may be helpful diagnostic tools in terms of prediction of post-operative LV remodeling.Severe AVS is associated with increased hemodynamic load and significant LV remodeling (encompassing hypertrophy and fibrosis), finally leading to impaired myocardial function and poor outcome in the absence of appropriate treatmentOur population, although significant, could result too limited in number since the multiple phenotypes of AS patients described. Furthermore, a control population for miRNAs was not included. However, previous papers hadalready shown data on AVS patients vs a normal population, so we mainly aimed at examining a differential miRNA-level distribution in anhomogeneous population (severe symptomatic AVS).34, even predicting the development of systo-diastolic dysfunction.AVS Common characterization cannot fully elucidate the complex pathophysiology of the cardiac remodeling process. Myocardial hypertrophy, fibrosis and apoptosis represent the main actors of cardiac remodeling in AVS: these patterns are regulated not only by pressure overload, but also by a complex network of humoral modulators. Our study aims at proposing a model of translational research inAVSfor a better diagnostic and prognostic patient stratification. Different phenotypes of AVS, with variable degrees of functional and hemodynamic impairment, express differential levels and types of circulating miRNAs. In this scenario, miRNAs could supply a more integrated knowledge of the disease and become amarker of fibrosis/adverse hypertrophic stimulusSUPPLEMENTARY MATERIAL