Current treatment paradigms for end-stage dilated cardiomyopathy (DCM) in children include heart transplantation and mechanical support devices. However, waitlist mortality, shortage of smaller donors, time-limited durability of grafts, and thrombo-hemorrhagic events affect long-term outcomes. Moreover, both these options are noncurative and cannot preserve the native heart function. Pulmonary artery banding (PAB) has been reinvented as a possible “regenerative surgery” to retrain the decompensated left ventricle in children with DCM. The rationale is to promote positive ventricular–ventricular interactions that result in recovery of left ventricular function in one out of two children, allowing transplantation delisting. Although promising, global experience with this technique is still limited, and several surgical centers are reluctant to adopt PAB since its exact biological bases remain unknown. In the present review, we summarize the clinical, functional, and molecular known and supposed working mechanisms of PAB in children with DCM. From its proven efficacy in the clinical setting, we described the macroscopic geometrical and functional changes in biventricular performance promoted by PAB. We finally speculated on the possible underlying molecular pathways recruited by PAB. An evidence-based explanation of the working mechanisms of PAB is still awaited to support wider adoption of this surgical option for pediatric heart failure. Pediatric heart failure (HF) represents an important cause of morbidity and mortality in childhood, with various causes . Management of end-stage HF in infants and children remains challenging. The ultimate therapy for end-stage HF is heart transplantation (HTX). However, the survival rates after HTX are suboptimal since the patient’s prognosis drastically decreases with time, with the overall 25-year survival as low as 37% . This maIn the present review, we collate the current knowledge on the use of pulmonary artery banding (PAB) as an alternative treatment option for left ventricular (LV) rehabilitation in children affected by dilated cardiomyopathy (DCM), addressing its observed and speculated biological working mechanisms. Starting from our clinical experience, we propose novel suggestions and refinements of current selection criteria, which we learnt from our cohort of children with DCM treated with PAB, for a more cautious application of this technique. Moreover, we present our hypotheses on the possible underlying molecular pathways recruited by this technique, with the aim of stimulating targeted experimental research on the regenerative properties of PAB. A wider scientific consensus on the efficacy of PAB in reverting HF is still awaited to support the adoption of PAB as part of treatment paradigms for pediatric HF.In the pediatric population, HF is still a field where more questions than answers exist. The incidence of HF in European countries ranges from 1 to 3 cases per 100,000 children, and the main etiologies are congenital heart diseases and cardiomyopathies . DilatedWhen medical therapy is ineffective, patients are evaluated for HTX and/or mechanical circulatory support (MCS). Unfortunately, the number of listed children still exceeds the number of potential donors, and waitlist mortality can reach 30% ,5. MoreoA growing number of pediatric patients are nowadays bridged to HTX with MCS ,7. GuaraHowever, both these strategies are noncurative and turn the primary cardiac pathology into a chronic systemic disease. The immunosuppressive regimen and related risks of infection and malignancy represent the main concerns in pediatric HTX ,10, as wMeanwhile, regenerative medicine has become a concrete possibility in a constantly increasing number of clinical settings . AvoidinDuring the progression of HF, the heart gradually loses the ability to replace damaged tissues and regenerate . Aiming Several protocols have passed the preclinical phase successfully and have been proposed for clinical experimentation. Intracoronary infusion of cardiac progenitor cells in patients affected by single-ventricle physiology has shown the possibility of reverse remodeling, which ameliorates the ventricular contractility, volumes, and functional status of patients ,23. MoreFirstly, proposed in 2007 by the Giessen working group , reversiAfter fifteen years from the first case report of the successful application of PAB in a 2-month-old baby with DCM , less thThe international experience with PAB was consolidated in a multicenter study, for a total of 70 patients from 15 institutions worldwide . In thisMore recently, a multicenter US study enrolling 14 children banded at a median of 5 months of age highlighted some differences with respect to the German experience . FunctioSince 2015, we have embarked on a surgical protocol alternative to HTX to treat pediatric end-stage HF , includiIn four patients (50%) in our cohort, LV performance improved significantly, allowing transplantation delisting. In the remaining two patients (the most recent ones), LV function is still depressed, but clinical conditions are stable, and the patients are kept on an active transplantation waitlist . At a meOur pre- and postoperative imaging protocol relies on transthoracic echocardiography, which is performed before surgery in the early postoperative period, at discharge, and then monthly for the first 6 months. Depending on clinical conditions, echocardiography is performed less frequently after 6 months. Paramount echocardiographic measures are RV function  and dimensions, tricuspid valve competence and Doppler inflow waves, and possible signs of pulmonary hypertension. Echocardiography is used to rule out any associated congenital heart defects, especially coronary anomalies. Left ventricular dimensions and function , parietal thickness, mitral valve competence and Doppler inflow waves, and intraventricular septum curvature are used to monitor the response to PAB. When feasible, we also perform cardiac magnetic resonance imaging (MRI) before PAB and 6–12 months after surgery. We suggest cardiac MRI as a standard preoperative imaging technique  for all candidates for PAB, and a second cardiac MRI at 6–12 months would be advisable to evaluate late myocardial remodeling. Cardiac MRI is helpful to better define biventricular volumes and geometries, quantify RV and LV ejection fraction and strain parameters, rule out associated congenital heart defects and coronary anomalies, and identify and quantify myocardial fibrosis (LGE positivity), if present. This piece of information may help clinicians in the definition of the prognosis and the feasibility of myocardial remodeling after PAB.The neonatal heart is demonstrated to possess a robust capacity for myocardial tissue regeneration, through the presence of highly active cardiac progenitor cells . In factWhile cardiomyocytes show robust replicative activity during embryonic and fetal development, with subsequent waves of proliferation , replicaAn ancient organ size control pathway  specifically inhibits cardiomyocyte proliferation in the adult heart ,49. ReguIn our experience, a possible cause of PAB failure is the age of patients . SchranzAlthough our hypotheses require further validation, surgeons should be aware that rates of PAB nonresponders in pediatric DCM and, subsequently, mortality, may be age-related. A deeper analysis of the international registries on PAB as well as targeted experimental research is hoped to clarify this topic.In nine patients from the worldwide multicenter cohort , PAB wasOne of the most important advantages of PAB is the minimal surgical invasiveness, requiring neither cardioplegic arrest of the heart nor cardiopulmonary bypass. As described in adult cardiac diseases, the more profound the LV dysfunction is, the less the cardioplegic arrest of the heart is tolerated . Due to On a molecular basis, in patients with HF, the ischemic/reperfusion injury associated with the cardioplegic arrest of the heart results in an exasperated inflammatory response and myocardial cytokine release when compared to nonfailing hearts . Thus, tAccording to the worldwide network report by Schranz et al. , PAB in For this reason, we strongly recommend that PAB be considered as a surgical option exclusively in patients who are eligible for long-term MCS. Complete patient assessment for MCS, family counseling, and notification to manufacturers must be integral parts of the preoperative planning of PAB . Since iThe first hypotheses for the mechanisms of action of PAB have been derived from the echocardiographic follow-up of patients. PAB responders usually display a gradual improvement in LV ejection fraction, even at discharge, which becomes more evident 3 to 6 months after the operation ,68. DataOne of the main concerns about the efficacy of PAB is the possibility of having selected those patients affected by DCM in whom the LV would have recovered anyway, independently from PAB. Spontaneous healing is possible in 10–20% of patients with DCM, especially when a myocarditis-based mechanism is suspected ,70. HoweNovel insights into ventricular–ventricular positive interactions recruited by PAB in DCM have been provided by MRI and speckle-tracking imaging ,72. CompIncrease in RV wall stress, which translates into RV hypertrophy and enhanced contractility due to the Anrep effect.Leftward shift of the interventricular septum that contributes to LV reshaping and restoration of an ellipsoidal rather than spherical shape.Reduction in LV preload and end-diastolic pressure, with subsequent optimization of the Frank–Starling curve and LV diastolic function.Decrease in LV dilatation during the whole cardiac cycle.Better left atrial–ventricular coupling and reduction in the severity of mitral regurgitation.Enhanced LV contractility.Reestablishment of biventricular synchrony.To summarize, PAB promotes the following hemodynamic changes :IncreaseTo date, the biological pathways recruited by PAB are still unidentified and knowledge gaps exist regarding the molecular-, cellular-, and tissue-level working mechanisms of this procedure. To test this novel therapeutic approach to HF in a controlled manner, a viable and reproducible animal model of DCM with hypothesized rescue using PAB is paramount. Yerebakan et al. proposed an innovative experimental sheep model of LV failure generated by intermittent intracoronary injections of doxorubicin treated with PAB . EchocarPAB is hypothesized to promote the regenerative capacity of the myocardium. Cardiomyocytes can detect wall stress modifications through integrin transmembrane receptors located in the sarcolemma . MoreoveIn this view, the effects of PAB could go beyond the initial Anrep effect on the RV and the optimization of the Frank–Starling curve for the LV. If demonstrated, the increased afterload caused by PAB would reactivate the proliferative potential of cardiomyocytes, stimulating a more profound LV rehabilitation. Moreover, acting as a promoter of the antioxidant defenses (through a supposed overexpression of YAP), PAB would reduce oxidative mitochondrial stress and related cell injury, which are common components of different etiologies of DCM .Proteomic analysis of rats undergoing PAB demonstrated clear modifications of the energetic, antioxidant, and structural pathways induced by the increased afterload . A metabPeculiarly, the response to afterload augmentation between the two ventricles presents some diverging points at the protein level. Friehs et al. compared the proteomic profile of neonate rabbits undergoing aortic constriction vs. PAB, identifying increased protein expression levels for structural constituents of the myocardium, myocardial tissue development, and calcium handling only in the latter animals . These fUnderstanding the biological working mechanisms of PAB is mandatory to achieve a wider scientific consensus on the efficacy of PAB in reverting HF, with a consequent higher adoption of this procedure as part of treatment paradigms for pediatric HF. Children with DCM will benefit from a simple and less invasive surgical option that allows the preservation of the native heart, postponing, or, hopefully, avoiding the need for HTX and MCS. Moreover, molecular pathways promoted by PAB could serve as targets for actionable and novel treatment concepts. Therapeutically promising up- or down-regulated molecules identified in this particular population could be modulated by known pharmacologic inhibitors or activators to further optimize the clinical results of PAB in DCM and, eventually, bypass surgical treatment.To date, one of most limiting factors that contributes to the skepticism towards the use of PAB in DCM is the still small number of treated patients. Our cohort, although it represents one of the largest reported single-center experiences with this technique, relies on a relatively small number of patients, which limits the translatability of our findings. We hope that our work would stimulate the prospective enrollment of a greater number of patients to be considered for this treatment.Furthermore, the possible biological working mechanisms of PAB that we hypothesized in the present work still require validation, which we aimed to encourage in future experimental research.In clinical practice, PAB proved to have a concrete potential in restoring LV function in one out of two children affected by end-stage DCM. Through the re-establishment of adequate LV preload, ellipsoidal shape, and biventricular synchrony, PAB enhances myocardial contractility and promotes ventricular–ventricular positive interactions in selected patients. However, several surgical centers are still reluctant to adopt this technique, because the precise biological pathways recruited by PAB and the ultimate clinical outcomes remain unknown. To date, we can propose only speculative hypotheses derived from ongoing animal experimentations on myocardial healing after an injury and from human data in similar clinical settings, such as the morphological LV retraining in congenitally corrected transposition of the great arteries. Understanding the cellular and molecular working mechanisms of PAB is mandatory to provide an evidence-based explanation in support of this approach. Experimental and targeted research is awaited to extend the implementation of PAB into the surgical toolbox for the treatment of pediatric HF and refine its efficacy.


Background and Objectives: The heart is the organ with the highest metabolic demand in the body, and it relies on high ATP turnover and efficient energy substrate utilisation in order to function normally. The derangement of myocardial energetics may lead to abnormalities in cardiac metabolism, which herald the symptoms of heart failure (HF). In addition, phosphorus magnetic resonance spectroscopy (31P MRS) is the only available non-invasive method that allows clinicians and researchers to evaluate the myocardial metabolic state in vivo. This review summarises the importance of myocardial energetics and provides a systematic review of all the available research studies utilising 31P MRS to evaluate patients with a range of cardiac pathologies. Materials and Methods: We have performed a systematic review of all available studies that used 31P MRS for the investigation of myocardial energetics in cardiovascular disease. Results: A systematic search of the Medline database, the Cochrane library, and Web of Science yielded 1092 results, out of which 62 studies were included in the systematic review. The 31P MRS has been used in numerous studies and has demonstrated that impaired myocardial energetics is often the beginning of pathological processes in several cardiac pathologies. Conclusions: The 31P MRS has become a valuable tool in the understanding of myocardial metabolic changes and their impact on the diagnosis, risk stratification, and prognosis of patients with cardiovascular diseases. Myocardial energetics represent one of the most important biochemical processes in the human body. A heart that functions well also has a normal cardiac metabolic profile. Derangement of this metabolic profile heralds the pathophysiological processes that subsequently lead to heart failure symptoms. This “engine out of fuel,” as the failing heart has previously been described , needs t31P MRS) began. These were ex vivo studies that, given the limitations of spatial localization techniques, focused on the energetics of animal hearts [31P MRS has significantly contributed to clinical research, and by providing invaluable insights on cardiac energetics, it has become a powerful non-invasive tool that enables the study of the most metabolically demanding organ in vivo, the heart.The correlation of biochemical pathways with metabolic function and energetic state in active tissues is a challenging project that researchers have acknowledged since the late 1970s . At the l hearts ,3,4,5. Hl hearts ,7. Since31P MRS plays in the thorough assessment of this link. It also provides a systematic review of the available studies in the literature that have used 31P MRS for the assessment of cardiovascular diseases in humans and the prognostic implications of their findings.This comprehensive review examines the link between cardiac energetics and cardiovascular disease and the important role that 31P MRS for the investigation of myocardial energetics in cardiovascular disease. The two independent investigators (V.T. and G.B.) performed a systematic search in the Medline database, the Cochrane library, and Web of Science from inception to 30 September 2022. No limitations were used in the search strategy. The following algorithm was used to retrieve all relevant studies for “cardiovascular disease AND (31P spectroscopy OR phosphorus spectroscopy)”.We have performed a systematic review of all available studies that used 31P MRS for the investigation of myocardial energetics in cardiovascular disease. In addition, we excluded studies that were conducted in animals or ex vivo.We considered eligible all studies that used The following data were extracted for each included study: publication data , patient characteristics , and the reported outcomes.Our search strategy returned 1092 possible relevant studies. Of them, 10 studies were excluded as duplicate records, 964 studies were excluded at the title/abstract level, while 56 studies were excluded at the full-text level. As a result, 62 studies were finally included in the review. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) flow diagram of the study population process is shown in The heart has been described as the organ with the highest metabolic demand, consuming 8% of the total body adenosine triphosphate (ATP) ,68. ConsThe healthy adult heart primarily uses free fatty acids and glucose as its main energy substrates ,72,73, wIn order to meet these high metabolic demands, the adult heart uses the above energy substrates to generate ample amounts of ATP, mainly through mitochondrial oxidative phosphorylation, which makes up to 95% of myocardial ATP, while a smaller amount is generated through glycolysis ,71. The The PCr is the primary energy reserve metabolite in the heart, with its concentration being twice that of ATP phosphorylation . However31P MRS is a non-invasive technique that provides unique insights into the abovementioned intracellular parameters through the detection of phosphorus-containing metabolites. It therefore allows an accurate evaluation of the myocardial energetic state through measurement of the myocardial PCr/ATP ratio as well as absolute levels of high-energy phosphates [31P MRS data [The osphates ,83. On mMRS data . In addiMRS data .31P nuclei with RF signals is required for 31P MRS. However, in following the excitation of the nuclei, the induced signal is recorded in the receiver coils of the scanner after the RF energy is switched off [The excitation of ched off . The ampched off . The resched off ,85. Thisched off ,85. Furt31P cardiac spectrum demonstrates peaks for phosphocreatine and the three phosphorus nuclei of ATP . The area under the peak is proportional to the relative concentrations of these metabolites [The typical 31P MRS is typically performed on MR scanners with a field strength of 1.5 or 3 Tesla(T), although studies using a higher field strength of 7T have been reported [The cardiac reported ,87. As treported ,87  Depth-resolved surface coil spectroscopy (DRESS): a single slice parallel to the coil is selectively excited by an MRI gradient. (b) Image selected in-vivo spectroscopy (ISIS): data are acquired using data from inversion pulses from consecutive cycles, and voxel localisation is achieved using a slice-based intersection strategy. (c) One-, two- and three- dimensional  chemical shift imaging (CSI): this technique uses phase encoding for spatial localisation, and the spectra can be acquired in a column of voxels (1D), a plane (2D), or a block (3D) of voxels [31P contributions from skeletal muscle and the liver [A cardiac f voxels ,88,89. The liver ,89.31P spectrum can be acquired. However, through analysis of this spectrum, the PCr/ATP ratio can be determined, allowing in this way an evaluation of the cardiac energetic state. In addition, the cellular pH  relative to PCr) can be indirectly deduced from the acquired spectra [31P MRS can also provide a unique insight into dynamic changes in the cellular metabolism through assessment of the CK flux and the rate of ATP generation [kf) of CK in the ATP-generating (forward) direction is first measured. This is then multiplied by the PCr/ATP ratio to give the forward CK flux, i.e., the ATP delivery rate [Using one or a combination of the aforementioned techniques, a localised cardiac  spectra ,85,90. Aneration ,24,30. Fery rate .31P MRS is its intrinsically low SNR (approximately 105-fold lower than 1H-MRS), which is typically compensated via coarser spatial and temporal resolutions [The major limitation of olutions ,87,89. Tolutions ,87,89. T31P MRS is the only technique available with the ability to study this pathological alteration in cellular metabolism in vivo, which is reflected in changes in cellular ATP and PCr concentrations, the PCr/ATP ratio, as well as the rate of ATP production as reflected by the CK flux. The research community has provided promising evidence that the role of 31P MRS is crucial in the early detection of pathological changes of the myocardial energetics through an exponential growth of clinical research studies over the last four decades.Numerous studies have shown that, in a cardiovascular disease state, there is significant impairment of energy production mediated by mitochondrial dysfunction, alterations in energy substrate utilisation, and impaired ATP transfer and utilisation ,68. The 31P MRS 3 weeks post MI and the PCr/ATP ratio was found to be normal in viable myocardium [The cardiac energy metabolism appears to be significantly impaired both in the infarcted and in the ischaemic myocardium. Following myocardial infarction, the concentrations of both PCr and ATP metabolites fall significantly ,18. In aocardium .There is only one study that investigated the potential changes in myocardial energetics in patients with normal epicardial coronary arteries. Buchthal et al. recruited 35 female patients who had been admitted to the hospital with cardiac chest pain and had normal invasive coronary angiograms. A total of Seven of the 35 women (20%) had significantly reduced cardiac PCr/ATP ratios during handgrip exercise, suggesting potentially significant abnormal myocardial metabolism in this population .The DCM exhibits impaired myocardial energetics, with reduced PCr and ATP concentrations, and PCr/ATP ratios ,25,26,33The PCr/ATP ratio is significantly reduced in patients with HCM, highlighting the abnormal myocardial metabolic changes in this population too. Early studies from almost three decades ago demonstrated unanimously that HCM is associated with impaired myocardial energetics ,34,37,90Despite the complex and heterogeneous cohort of patients that comprise the clinical entity of HFpEF, the myocardial energetics display a uniform impairment, reflected by a significant reduction in the PCr/ATP ratio ,50. In aBoth aortic and mitral valve disease have been shown to have a significant impact on the myocardium . This is31P MRS has also revealed valuable insights in the pathophysiology of cardiac allografts and is a promising non-invasive tool that can efficiently assess cardiac allograft vasculopathy (CAV). In a study that included 25 heart transplant recipients, Evanochko et al. used a 31P MRS stress test and found that certain patients have abnormal cardiac energetics after transplantation, as reflected by a significant change in the PCr/ATP ratio [31P MRS stress test may have an important role in the diagnosis of CAV as it is a much more sensitive means of assessing the microvasculature [31P MRS is a promising tool able to detect impairment of myocardial energetics related to CAV, with a PCr/ATP value of 1.59 being their proposed optimal cut-off value to predict CAV with specificity and sensitivity of 100% and 72%, respectively [31P MRS is not standard as yet; hence, such cut-offs only apply to the particular methodology and the specific MRI scanner used in this study.The TP ratio . This apculature . SimilarAs noted above, the metabolism has a central role in the pathogenesis of a range of cardiovascular diseases. As such, medical therapies targeted at the metabolic pathways that have a key role in these diseases are extremely beneficial for the patients. This has been shown for several medications that have been proven to be not only of symptomatic but also of prognostic benefit. For example, beta blockers have been shown to increase the PCr/ATP ratio by 33% in patients with heart failure after only 3 months of treatment , and, si31P MRS will continue to have an instrumental part in this journey as it provides a non-invasive and accurate evaluation of the cardiac metabolic profile that helps researchers gain important insights into the complex pathophysiology of cardiac disorders. The current limiting factors in the widespread use of 31P MRS include the requirement of both expensive hardware and clinical expertise. Nevertheless, as research emphasises the importance of myocardial energy reserve in the pathophysiology of disease and pharmacotherapy, these issues will gradually recede.The cardiovascular research has now shifted to treatments that focus on the improvement of myocardial energetics and metabolism, which play a pivotal role in the pathogenesis of several cardiovascular diseases. The 31P MRS is the only available non-invasive technique with the capacity to quantify metabolism in vivo, and it is, therefore, an excellent tool in the evaluation of the myocardial metabolic profile of patients with cardiac pathologies. Future studies assessing myocardial energetic phenotypes and how these are associated with clinical outcomes and prognosis will help further in understanding the impact of altered metabolism in clinical practice.The myocardial energetic compromise has proved to be an important feature in the pathophysiological process of several conditions. The


CMR was used to determine the presence and extent of LGE. Several collagen turnover biomarkers were determined at diagnosis, comprising galectin-3 , procollagen type I carboxy-terminal pro-peptide (PICP) and N-terminal pro-peptide of procollagen type III (PIIINP). A composite outcome  was ascertained over a median of 26 months. Results: Gal3, PICP and PIIINP were considerably increased in those with LGE+ (p < 0.001), also being directly correlated with LGE mass . Receiver operating characteristic (ROC) analysis revealed a significant ability to diagnose LGE, with an area under the ROC of 0.816 for Gal3, 0.705 for PICP, and 0.757 for PIIINP . Kaplan–Meier analysis showed that at a threshold of >13.8 ng/dL for Gal3 and >97 ng/dL for PICP, they were able to significantly predict outcome . Of all patients, 17% (n = 33) reached the outcome. In multivariate analysis, after adjustment for covariates, only LGE+ and Gal3+ remained independent predictors for outcome . Nonetheless, collagen turnover biomarkers were closely related to HF severity, providing incremental predictive value for severely decreased LVEF of under 30% in patients with NIDCM, beyond that with LGE alone. Conclusions: In patients with NIDCM, circulating collagen turnover biomarkers such as Gal3, PICP and PIIINP are closely related to the presence and extent of LGE and can significantly predict cardiovascular outcome. The joint use of LGE with Gal3 and PICP significantly improved outcome prediction.Background: Myocardial scarring is a primary pathogenetic process in nonischemic dilated cardiomyopathy (NIDCM) that is responsible for progressive cardiac remodeling and heart failure, severely impacting the survival of these patients. Although several collagen turnover biomarkers have been associated with myocardial fibrosis, their clinical utility is still limited. Late gadolinium enhancement (LGE) determined by cardiac magnetic resonance imaging (CMR) has become a feasible method to detect myocardial replacement fibrosis. We sought to evaluate the association between collagen turnover biomarkers and replacement myocardial scarring by CMR and, also, to test their ability to predict outcome in conjunction with LGE in patients with NIDCM. Method: We conducted a prospective study on 194 patients  with NIDCM. The inclusion criteria were similar to those for the definition of NIDCM, performed exclusively by CMR: (1) LV dilation with an LV end-diastolic volume (LVEDV) of over 97 mL/m Despite recent therapeutic developments, non-ischemic dilated cardiomyopathy (NIDCM) remains a primary cause of progressive cardiac remodeling and heart failure (HF) that leads to frequent hospitalization and increased mortality. These patients have an increased risk of developing myocardial fibrosis, which, in turn, plays a central role in the progression of HF . CardiacMolecular markers of fibrosis such as galectin-3 , procollagen type I carboxy-terminal pro-peptide (PICP) and N-terminal pro-peptide of procollagen type III (PIIINP) are in direct relationship with myocardial collagen turnover, and thus might aid in the prediction of major adverse cardiovascular events (MACEs) . Gal3 biTo date, PICP and PIIINP are the only proven peptides that can be identified in the bloodstream that are considerably correlated to histologically proven myocardial fibrosis . These mThe aim of this study was to evaluate the link between circulating collagen turnover biomarkers and myocardial replacement fibrosis determined by CMR, and also to test their ability to predict outcome in conjunction with LGE.2; (2) global LV dysfunction, expressed as a decreased LVEF of under 45% [We conducted an observational, prospective study on patients recently diagnosed with NIDCM who were examined in the Department of Internal Medicine, Iuliu Hatieganu University of Medicine and Pharmacy of Cluj-Napoca, between October 2017 and November 2020. The inclusion criteria were similar to those for the definition of NIDCM, performed exclusively by CMR: (1) LV dilation with an LV end-diastolic volume (LVEDV) of over 97 mL/mAll patients underwent a similar investigation protocol, which included demographic and clinical data and biological sampling, along with standard cardiovascular evaluation and CMR.2.Biochemical workups were performed in the Clinical Biochemistry Laboratory from the 2nd Medical Clinic of the Cluj Emergency County Hospital. Two peripheral venous blood samples were harvested, centrifuged immediately after, and stored in special vials with ethylenediaminetetraacetic acid. Sera glucose and creatinine were determined from one vial using a Konelab-31 analyzer, while the other vial was stored at −70 °C until the end of the study and used to determine the serum levels of cardiac biomarkers. PICP, PIIINP, copeptin (CPP) and N-terminal pro-Brain Natriuretic Peptide (NT-proBNP) were determined by the Sandwich ELISA technique according to the manufacturer’s recommendations using Elabscience Biotechnology Co., Ltd, Wuhan, China. The inferior thresholds and variabilities for these markers were as follows: for PICP, a cut-off value of 0.13 ng/mL and inter-/intra-test variability <10%/<12%; for PIIINP, a cut-off value of 0.14 ng/mL and inter-/intra-test variability <10%; for CPP, a cut-off value of 0.18 ng/mL and inter-/intra-test variability <10%; for NT-proBNP, a cut-off value of 0.38 ng/mL and inter-/intra-test variability <10%. Serum levels of Gal3 were measured using an enzyme-linked immunosorbent assay , with an inferior cut-off value of 0.016 ng/mL, without crosslinked reactivity with other galectin or collagen molecules. Intra-test and inter-test plasma variations for Gal3 were 3.5–4.3%, and 5.8–6%, respectively. Renal function was evaluated using the estimated glomerular filtration rate (eGFR) and renal impairment was considered as an eGFR of under 60 mL/min/1.73 mCMR images were appraised using a 1.5 T Open Bore system MR scanner  in complete apnea by two level-III experienced operators who were blinded to all clinical and imaging data, in line with current international guidelines . The acqFocal myocardial fibrosis was evaluated by LGE detected at 10 min after intravenous infusion of 0.2 mmol/kg gadoxetic acid  using long- and short axis-views, using a segmented inversion-recovery gradient-echo sequence. LGE acquisition parameters were TR 4.8 ms, TE 1.3 ms and inversion time 200 to 300 ms. Inversion time was adjusted to optimize nulling of normal myocardium. Brachial blood pressure was monitored during SSFP-CMR acquisitions.3) [LVEDV, LV end-systolic volume (LVESV), LVEF and end-diastolic LV mass (LVM) were measured on short-axis cine-SSFP images. Epicardial and endocardial borders were traced semi-automatically at end-diastole and end-systole using a Syngo Virtual Cockpit. All volumes were indexed to body surface area (BSA). Besides this, for a more accurate assessment of LV function, we assessed the LV longitudinal-axis strain  and LV sphericity index (LVSI). The LVSI was calculated by dividing LVEDV by the volume of a sphere, whose LV length (L) was measured at the end-diastole: LVSI = LVEDV/(π/6 × (L)3) ,20.The presence and distribution of LGE in the LV were assessed from short-axis images using the 17-segments model, as recommended by the American Heart Association , and quaThe clinical follow-up was obtained by completing a questionnaire either during hospital visits, telephone house-calls, or both—aiming to delineate the occurrence of clinical outcomes, which corresponded to the first event occurring in each patient among the following MACEs: death or aborted death from cardiac causes, sustained ventricular tachyarrhythmia (beats with ventricular origin that last >30 s and have a rate greater than >100 beats/min), and HF requiring hospitalization—defined according to current international guidelines. Hospitalization due to non-cardiac causes was not counted as an event. Survival analysis was performed for the clinical outcomes. The median follow-up was 26 months and maximum follow-up reached 41 months.2 and Fischer tests for qualitative data and ANOVA or Kruskal–Wallis H tests for continuous data. Pearson’s coefficient of correlation was used to examine the relationship between data. Furthermore, for specific descriptive analyses, the studied population was dichotomized according to LGE presence (LGE+) or absence (LGE−), and also with respect to higher than median levels of PICP, PIIINP and Gal3  and lower than median levels of these biomarkers —thus resulting in six specific groups. Also, logistic regression was used to evaluate the incremental ability of these markers.Initially, the Kolmogorov–Smirnov test was used to assess data normality. Continuous data were presented as median (inter-quartile range (IQR)) and mean ± standard deviation (SD). Discrete data were reported as percentages and frequencies. The distribution of variables was accounted for after logarithmic transformation. Comparisons between groups were approached using HiKaplan–Meier survival curves were created and differences between groups were assessed using log-rank tests. Unadjusted and adjusted Cox regression analysis was performed to determine hazard rates (HRs) and 95% confidence intervals (CIs). Furthermore, adjustment regression models were used to test if the biomarkers of cardiac fibrosis did or did not respect a linear trend. For the adjustment, specific covariates which are known to significantly predict outcome in patients with NIDCM such as LVEF, eGFR, body-mass index (BMI), NT-proBNP, diabetes, gender and age were used. Moreover, ROC analyses were used to calculate the cut-off values of circulating biomarkers for predicting MACEs.Additionally, inter- and intra-observer Kappa Cohen coefficients were calculated. Retrospective calculus of statistical test powers and prospective dimensions of the sample were estimated using type I and type II variations, based on sample size. The statistical analysis was performed using statistical software MedCalc .p < 0.001; 156 ng/mL vs. 74 ng/mL, p < 0.001; and 5.1 ng/mL vs. 3.5 ng/mL, p < 0.001, respectively. Moreover, patients with LGE+ had significantly modified LVEDV , LVESV , LVSI  and LV-LAS , and significantly lower LVEF .A total of 194 patients with NIDCM were enrolled in the study and their main characteristics are presented in 2 = 0.372, p < 0.0001; r2 = 0.379, p < 0.0001; and r2 = 0.315, p < 0.0001. ROC analysis demonstrated that specific cut-off values significantly identified the presence of LGE: an area under the ROC of 0.816 for Gal3 , 0.705 for PICP  and of 0.757 for PIIINP , as compared to those without LGE . Further2 = −0.58, p < 0.0001; r2 = −0.39, p < 0.0001) and NYHA class ≥III , and directly correlated with NT-proBNP  and CCP  levels.Regarding the relationship between circulating collagen turnover biomarkers and the severity of HF, Gal3 and PICP were inversely correlated with LVEF (rn = 61) of patients had a severely decreased LVEF of under 30%. These patients had significantly impaired LVEDV, LVESV, LVSI and LV-LAS  and considerably higher LGE mass  and LGE mass/LV mass ratios , as compared to those with LVEFs over 30%.As shown in p < 0.001 and CPP: 17.5 ng/mL vs. 9.5 ng/mL, p < 0.001, respectively.Sera markers of HF were notably increased in those with LVEF < 30%: NT-proBNP: 17,500 ng/L vs. 16,200 ng/L, p < 0.0001). The addition of Gal3 to LGE significantly increased the diagnosis power , while further adding PICP increased their identification ability even more . Lastly, the association of Gal3, PICP and PIIINP with LGE provided a significant incremental value for predicting decreased LVEFs of <30% in patients with NIDCM  of patients reached the outcome: all-cause mortality (n = 6), malignant ventricular tachyarrhythmia (n = 14) and HF hospitalization  were significantly associated with MACEs. However, following the multivariate analysis, after adjustment for covariates comprised of age, gender, LVEF, eGFR, BMI, NT-proBNP and diabetes mellitus, only LGE+ and Gal3 remained independent predictors for MACEs .Furthermore, gradual logistic regression proportional-hazard models showed a significant incremental predictive ability by adding Gal3 to LGE used alone , p < 0.0001 and HR = 3.23, 95% CI (1.91–5.46), p < 0.0001.Moreover, a subgroup analysis that included patients with NIDCM and severely decreased LVEF (<30%) showed that, for similar cut-off values, Gal3  and PICPIn this study, we evaluated the association of circulating collagen turnover biomarkers with replacement myocardial fibrosis and with severely decreased LV systolic function, both determined by CMR, in patients with NIDCM. The main findings of our research article comprise: (1) sera levels of collagen turnover biomarkers, namely Gal3, PICP and PIIINP, were closely associated with CMR parameters of LV systolic dysfunction, such as LVEDV, LVESV, LVSI, LV-LAS—also being notably correlated with markers of HF severity, namely NYHA class ≥ III, NT-proBNP and CPP levels; (2) Gal3, PICP and PIIINP were directly associated with the mass of replacement myocardial fibrosis, represented as LGE mass and the LGE mass/LV mass ratio; (3) along with LGE, Gal3 and PICP were the most notable independent predictors of cardiovascular outcome; (4) the addition of Gal3, PICP and PIIINP provided an incremental ability to diagnose severely decreased LV systolic function in this category of patients.Cardiac fibrosis is frequently found in patients with NIDCM and is associated with a more aggressive disease phenotype, being more difficult to treat. At the root of these findings stands accelerated progression of LV dysfunction, congestive HF, and increased risk of sudden cardiac death ,23. PrevAmongst all the markers, Gal3 had the strongest predictive ability, being an independent predictor for outcome, together with LGE—even after the adjustment for standard covariates such as age, gender, LVEF, NYHA class, renal function, and NT-proBNP. Besides this, in our study, we have shown that circulant Gal3 was independently associated with myocardial fibrosis, quantified as LGE by CMR in patients with NIDCM—this being another innovative aspect of our research. Similarly, Vergaro et al. have shown that plasmatic levels of Gal3 are closely associated with LGE in patients with NIDCM . AdditioSera PICP was reported to be an important circulant marker of type I collagen turnover, being significantly associated with myocardial fibrosis  and withFurthermore, we evaluated the profile of these biomarkers in patients with NIDCM and severely decreased LVEF of under 30%. All of them had significantly increased sera levels and were even closely related to HF parameters. Moreover, the stepwise addition of these biomarkers to LGE proved to increase their association with decreased LVEF, beyond that of each parameter used alone. Thus, our study suggests the utility of these sera biomarkers even in the risk stratification of these patients.Furthermore, the joint use of circulating biomarkers and LGE might become useful in monitoring disease progression and also in identifying patients who would benefit from implantable cardioverter devices or cardiac resynchronization therapy ,31, but Withal, an important issue that needs to be considered is that these biomarkers reflect the systemic metabolism of collagen, and not only in cardiac collagen; thus, this is the reason why these markers could become useful in heart diseases only when they can be combined with cardiovascular imaging parameters . LikewisFirstly, being a single-center study represents a limitation by default. Secondly, T1-maps and extracellular volumes were not assessed in all patients since this technique was not available in our research facility at the beginning of the study. Lastly, the long recruitment period might have affected the sera samples from which the biomarkers were determined.In patients with NIDCM, circulating collagen turnover biomarkers—namely Gal3, PICP and PIIINP—were independently associated with myocardial replacement fibrosis determined as LGE by CMR, being useful in the risk stratification of them. These markers were even higher in those with NIDCM and severely decreased LVEF. Moreover, they were useful in prognosis prediction; however, only Gal3 proved to be an independent predictor for cardiovascular outcome.


The health burden of heart failure with preserved ejection fraction is increasingly recognized. Despite improvements in diagnostic algorithms and established knowledge on the clinical trajectory, effective treatment options for heart failure with preserved ejection fraction remain limited, mainly because of the high mechanistic heterogeneity. Diagnostic scores, big data, and phenomapping categorization are proposed as key steps needed for progress. In the meantime, advancements in imaging techniques combined to high-fidelity pressure signaling analysis have uncovered right ventricular dysfunction as a mediator of heart failure with preserved ejection fraction progression and as major independent determinant of poor outcome. This review summarizes the current understanding of the pathophysiology of right ventricular dysfunction in heart failure with preserved ejection fraction covering the different right heart phenotypes and offering perspectives on new treatments targeting the right ventricle in its function and geometry. The phenogroup with RH disease included older subjects with the highest rate of comorbidities and had the worst hospitalization/mortality evolution. Similarly, in a recent machine learning analysis,8 the older phenogroup showed a poorer RV function and a higher burden of risk factors, such as atrial fibrillation (AF) and hypertension. In most conditions triggering HFpEF, RH disease develops as a consequence of enhanced left atrial pressure and pulmonary hypertension (PH).12 Of note, in 10% to 15% of cases of normal LV ejection fraction (EF), RH disease may be the consequence of infiltrative myocardial disease, such as amyloidosis,13 a condition requiring appropriate diagnosis and specific clarification as a final step in the diagnostic algorithm, according to the European Society of Cardiology Consensus Statement on HFpEF diagnosis.1 Mortality remains elevated irrespective of the etiology and the pre- or postcapillary nature of PH.14 Furthermore, given that in HFpEF the left heart dysfunction is typically associated with comorbid conditions, a specific contributory role of inflammation and oxidative stress in the adverse RH chamber remodeling and dysfunction may not be ruled out15 but rather represents an intriguing pathogenetic hypothesis to be tested in large numbers and multiple RH disease phenotypes.16 Hemodynamic injury and proinflammatory mediators combine with a multitude of gene expression and pathways involved in RV chamber response to injury.18 In a recent analyses of the PROMIS-HFpEF study exploring the protein biomarker that may support the HFpEF comorbidity-inflammation paradigm by a high throughput technology, Sanders-van Wijk et al19 found that systemic inflammation was associated with tricuspid regurgitation and worse RH function. The contribution of multiple pathways and the variable standard of measurements and cutoff for defining the RH disease well explain the heterogeneity observed in prevalence and clinical course itself.11 In the subgroup of patients investigated by echocardiography in the PARAGON-HF trial, the rate of RH disease was 30%.20 In the large HFpEF cohort of Olmsted County,9 RH disease occurred in 35% of cases, as assessed by tricuspid annular plane systolic excursion (TAPSE) measurements, and in 21% of cases by semiquantitative visual score analysis, suggesting a quite weak concordance between the two methods. A similar degree of failure, however, was found if both reduced TAPSE and low motion analysis coincided. RH disease patients were more likely to have AF and to receive higher doses of diuretics. An improved consensus on the diagnostic criteria of RH disease in HFpEF appears to be desirable.RH disease in HFpEF is highly prevalent6 AF and use of diuretics were consistently associated with the worst RH disease phenotypes. The recurrent link between RH disease development and AF has been confirmed in a number of investigations23 with some controversy as to whether AF being the cause or the consequence.24In a study phenotyping RH by assessing RV to Pc coupling by the TAPSE/PASP  ratio,23 recently addressed the time course of functional changes over a median follow-up of 4.0 years. They found a 10% decline in RV fractional area change and 21% increase in RV end-diastolic area. RH disease developed at a rate higher and faster than corresponding changes in the LV and was associated with coronary disease, greater body weight, higher PA and LV filling pressures, RV dilation, and, again, higher rate of AF. Interestingly, RV diastolic dysfunction and increased stiffness occurred before the development of systolic dysfunction, and subjects who developed incident RH disease exhibited a ≈2-fold increased risk of death. Along with these changes, reports document some myocardial fibrosis at the RV insertion points25 and even RV diffuse fibrosis as peculiar features in HFpEF.26 Interestingly, the myocardial fibrosis at the RV insertion point has been found to correlate with wedge, mean pulmonary, and right atrial pressures.25Although RH disease has been mostly studied in cross-sectional analyses, Obokata et al27 As such, the RV is sensitive to brisk increases in pulmonary arterial pressure (PAP), such as in massive pulmonary embolism or experimental PA banding, and may result in acute dilatation and rapidly fatal cardiogenic shock.28 However, if given time, the RV adapts to increased afterload by increased contractility thus preserving the Pc coupling and flow output response to metabolic demand. This has been established in experimental and clinical studies in which high-fidelity manometer-tipped catheters were used to derive RV end-systolic elastance (Ees) or end-systolic pressure (ESP) divided by end-systolic volume as gold standard measure of contractility and arterial elastance (Ea) or ESP divided by stroke volume as a validated lumped parameter of afterload.29 The Ees/Ea ratio measurement of RV-PA coupling is normally around 1.5. It is preserved during exercise in healthy subjects and is either preserved or decreased at rest but decreases during exercise in severely increased PAP such as in pulmonary arterial hypertension (PAH).30 The Ees/Ea ratio has some reserve, as it has to be decreased by some 50%, from 1.5 to around 0.8 until there is an increase in RV volumes. The Ees/Ea decreases to these critical values in pulmonary vascular disease with severe increases in PAP, such as PAH30 or chronic thromboembolic PH,31 but may already reach uncoupling values in the presence of mild to moderately increased PAP, as has been demonstrated in experimental HF.32The RV is a thin-walled volume generator functionally coupled to a low impedance Pc Figure .27 As su27 There is shared information content between the Ees/Ea ratio and EF, as the Ees/Ea ratio can indeed be simplified for a common term of ESP as stroke volume/end-systolic volume, which in turn is equal to EF/(1−EF).33 An Ees/Ea ratio of 0.8 corresponds to an EF of 35% to 40%.Dilatation of the RV signals a shift from homeometric (systolic function) adaptation (Anrep law) to heterometric adaptation (Starling law) to chronic loading conditions.27 As reported in the Figure Practically, RV dysfunction can be defined by a decreased Ees/Ea or EF but preserved end-diastolic volume and end-systolic volume and its transition from adaptive hypertrophy to failure by decreased Ees/Ea or EF and augmented end-diastolic volume and end-systolic volume above normal values.34 It is conceivable to suspect that the same would be true for HFpEF but this relevant aspect has not been yet systematically detailed in the evolving stages of PH due to HFpEF.35The pressure-volume loop also offers a diastolic elastance curve as a gold standard measure of diastolic function. The diastolic elastance curve has a curvilinearity that increases with increased end-diastolic volume and can be described by an equation that contains a diastolic stiffness coefficient, β. The diastolic stiffness of the RV correlates with disease severity in PAH.36 as a consequence of an increase in the pulsatile loading, which typically occurs in the presence of atrial myopathy and increased V wave, especially when associated with AF37 and atrial functional mitral regurgitation.38 The progressive impairment in LA dynamics becomes a central player in the pulmonary congestion cascade and a limiting step in the lung fluid clearance process favoring perivascular inflammatory reaction.39Increased LV filling pressures in HF, as assessed by pulmonary artery wedge pressure (PAWP) measurements, are initially transmitted upstream in a close to 1/1 relationship to mean PAP (mPAP) with unchanged pulmonary vascular resistance (PVR). Even with relatively normal PVR at rest, patients with HFpEF display a compromised pulmonary arterial compliance (PAC)27 Stiffening of the pulmonary vessels, starting from the venous system, further increases this gradient.All together, these mechanisms promote the time- and pressure-related pulmonary vascular remodeling and increase the gradient between PAWP and mPAP.40 RV afterload is determined by a dynamic interplay between PVR, PAC, and wave reflection.41 Although specific evidence in HFpEF patients is lacking, a number of studies have shown that wave reflection affects PA pressure curves by late systolic peaking of pressure and PA flow curves by late or midsystolic deceleration of flow.42 However, these morphological aspects do not necessarily impact on RV afterloading as the product of PVR and PAC or so-called time constant of the Pc (RC time) remains constant or nearly constant, allowing for an essentially unchanged oscillatory to steady flow work (Wosc/Wst) ratio of 25% in all PH conditions.43 Extreme reported variations of the RC time still do not prevent valid estimation of RV afterload by a total hydraulic load calculation (Wtot) as 1.2 to 1.4× Wst.44One could think of quantifying RV afterload by a PVR calculation, assuming Ea or ESP/stroke volume to be equal to PVR divided by heart rate and mPAP a satisfactory estimation of RV ESP. However, this approach is misleading because of variable underestimation of ESP by mPAP.45 However, whether a decreased PAC because of increased PAWP or altered left atrial structure and function may be sufficient to increase Wosc/Wst in HF patients remains to be established.This being said, the constant value of the product of PVR by PAC implies a hyperbolic relationship so that the relative contribution of PAC to afterload is greater in case of increased PAWP with normal or only mildly elevated mPAP. This may at least, in part, explain greater predictive capability of outcome of PAC versus PVR in HF patients and especially in HFpEF.46 The volume load of the tricuspid regurgitation can itself lead to further increase in RV dilatation and associated preload-induced increase in afterload as defined by RV wall tension. Moderate-to-severe tricuspid regurgitation is quite common in stage B and C HFpEF, and47 geometric changes in tricuspid valve and associated tricuspid insufficiency hold a considerable impact on survival.49RV distension is associated with functional tricuspid regurgitation from stretching of the tricuspid valve annulus. Tricuspid valve annulus dilates along the anterior and posterior aspects because of the relatively fixed portion of the medial aspects of the annulus. With this distension, there is a change in the shape of the valve with flattening and modifications of the normal papillary muscle to leaflet and valve relationship.50 The pericardium primarily contributes to the RV to LV interaction exerting a constraining effect.51 Ventricular interdependence is diastolic, which alters LV diastolic function by competition for space between the LV and the dilated RV within a nondistensible pericardium,51 but also systolic, which to some extent preserves RV contractility by the entrainment effect of preserved LV systolic function.22 In the end, negative diastolic interdependence may prevail, resulting in a low-cardiac-output state by decreasing LV distensibility and preload. Although these step-by-step variations in RV geometry and function have been well described in early HFrEF stages, there is now clear characterization in HFpEF.52 Specifically, in HFpEF, the role of an unfavorable diastolic ventricular interaction has been elegantly unmasked even in the early stages during exercise53  to the developed force (PASP).69 Interestingly, in PH-HFpEF, a TAPSE/PASP ratio of 0.36 discriminated pre- from postcapillary PH in patients with HF,70 and, based on these observations, TAPSE/PASP ratio has been used for screening different phenotypes of RV-Pc uncoupling in a parallel assessment of clinical characteristics, pulmonary and systemic hemodynamics, and outcome in HFpEF according to tertile group definition  mm/mm Hg and decreases slightly with aging.n Figure . Progres22 The analysis of this relationship showed a downward shift in the PH-HFpEF with AF compared with HFpEF free of AF unmasking some further degree of RV function mismatch due to a partially load-independent fashion. Other simplified surrogate approaches including RV EF (CMR), /PASP are clinically relevant,71 and more comprehensive and precise indicators such as the tissue Doppler S′ and the RV free wall strain appear promising. Nonetheless, TAPSE/PASP has been the first approach proposed and to date the only noninvasive echocardiography-derived indicator tested against invasive gold standard measures of Ees/area6 and Ees/Ea.66 Figure Echocardiography-derived approaches similar to the TAPSE/PASP ratio have been developed such as, for example, relating RV fractional area changes (%) to mPAP.72 At present, there are no data yet on the effects of fluid loading on RV-Pc coupling in HF. In healthy subjects, exercise is associated with a preserved RV Ees/Ea30 but a decreased TAPSE/PASP, which is accentuated with aging. Exercise decreases RV Ees/Ea in PAH, and, most recently, the same has been shown in HF. In that study, Ees/Ea was recalculated from RV pressure waveforms and was typically most decreased in patients with increased PVR. More data are needed to evaluate the clinical relevance of RV-Pc coupling measurements in fluid loading or exercise stress conditions in HFpEF.In most recent years, there has been a progressive need to recognize and explore the Pc and the RV as an integrated functional unit also during exercise and fluid loading especially in subjects with preserved LV EF and presenting with uncertain diagnosis of true HFpEF. A fluid challenge may be considered as a valid though less strenuous mean than exercise, to test RV function mainly through an increased systemic venous return.39 Specifically, therapeutic strategies should be aimed at contrasting the multifold pathways involved in lung capillary stress failure and remodeling,73 potentially targeting those that may embrace some combinatory biological effects on the pulmonary endothelium with a reverse remodeling of RV myocyte hypertrophy and extracellular matrix proliferation.74Since the RH is quite sensitive to an increase in afterload due to the elevated left atrial pressure, the first goal of therapy should be to reduce LV filling pressure with the double aims of (1) modulating the abnormal pulsatile loading on the RH and (2) avoiding fluid swelling from pulmonary capillaries to the interstitium with consequent increase in transmural arteriolar pressure and loss of PAC.75Effective decongestion is a must, and methods to obtain a long-lasting effect remain an important challenge with recent evidence pointing on devices to monitor intracardiac and pulmonary pressures.58 performed a prospective invasive hemodynamic and echocardiographic study uniquely examining resting RV and pulmonary vascular function along with RV-Pc coupling responses to acute β-adrenergic stimulation with dobutamine in patients with HFpEF at earlier stages versus controls. RV systolic and diastolic function were impaired in HFpEF subjects compared with controls using both invasive and noninvasive indices. Dynamic RV-Pc coupling analysis, assessed by either invasively determined dP/dt versus mPAP or semi-invasively by the echocardiography of tricuspid annulus tissue Doppler velocity s′ versus mPAP, suggested that RV systolic function was blunted during β-adrenergic stimulation in HFpEF and consequent pulmonary vasodilation compared with controls. These findings indicate that an altered pulmonary arterial tone is a major component of the syndrome, even at early stages when any increase in PAP is simply related to the backward passive effect of increased left atrial pressure. This evidence challenges the appropriate timing for interventions and the rationale of eventually using vasodilator agents.Andersen et alIntriguingly, the lack of an inotropic positive response during β-adrenergic stimulation could prospect and reinforce the hypothesis that as for the LV, the failing RV would present with β-adrenergic receptor desensitization. However, no specific data in HFpEF patients are available.76 historical studies performed with pulmonary vasodilators in HFpEF group 2 PH have not been encouraging and mostly negative.78 Nonetheless, study hypotheses, design, inclusion criteria, and phenotyping of populations have been quite incomplete, likely contributing to some delay in the search of effective compounds for RH dysfunction due to LV disease. Specifically, the most crucial questions that have been addressed only in part in the past are: which HFpEF phenotype may be more responsive to pulmonary vasodilators; how much to obtain RH unloading as compared with the biological effects; what pathways to target for expecting some reverse remodeling.Although efforts to effectively treat RV-Pc uncoupling in HFpEF are increasing,5 inhibition on both pulmonary hemodynamics and RV function were tested enrolling patients by a prespecified phenotyping process, that is, documented significant LV hypertrophy; RV-LV interaction ratio of RH  to left heart (PAWP) filling pressures >1; high PVR, increased elastance and documented pulmonary capillary damage .61 Sildenafil was effective on pulmonary hemodynamics, yielding to a significant RV-Pc recoupling and gas diffusion restoration. These findings have been recently confirmed by Belyavskiy et al79 in similar patients of combined pre- and postcapillary PH-HFpEF showing an improvement in RH hemodynamics and exercise performance.In a study of HFpEF with precapillary PH, the effects of PDE5 inhibition has not been documented for isolated postcapillary PH-HFpEF,80 and the RELAX trial exclusively based on estimated PASP led to neutral results as well.81The PASSION trial is underway and will test the effects of tadalafil on hard end points in a larger group of similarly phenotyped patients. The same potential for benefits of PDE5 inhibitors in PH-HFpEF (Table) and conceivably explains differences across studies.Overall, the evidence available to date points to the concept that a thorough RH phenotyping is preliminary to any further reasoning in the potential use of PDE82 In humans, findings with albuterol in HFpEF have shown an improvement in exercise pulmonary vascular reserve without worsening left heart congestion.83 Interestingly, some of the benefits observed with albuterol were driven by a reduction in LV transmural pressure suggesting an RV unloading effect due to perivascular and peribronchial fluid reabsorption and an RV unloading effect.Recently, treatment with β3AR (beta-3 adrenergic receptor) agonists has been found to improve pulmonary hemodynamics, RV remodeling, and pulmonary vascular proliferation in a translational porcine model of postcapillary chronic PH.84Similar findings have been described during acute administration of inhaled sodium nitrite showing a reduction in biventricular filling pressures and PAPs at rest and during exercise in HFpEF.85An ongoing study of combined pre- and postcapillary PH-HFpEF patients, the SPHERE HF, will test the effects of a β3AR, mirabegron, on RH performance using advanced imaging techniques  and several markers of subclinical myocardial disease  to address even subtle changes in RV function.86Promising results have been observed with the TRPV4  channel, which regulates fluid transit across the alveolar capillary interface and represents a novel target to reduce lung interstitial and perivascular water, independent of pulmonary capillary hypertension, definitively impacting the RV.87 but there is some concern on the temporal-related occurrence of RV dysfunction as suggested by experimental models.88An interesting nonpharmacological approach to the treatment of HFpEF is the interatrial communication device whose indications to implantation require no PH at rest and normal RV function. Whether this approach may delay or prevent development of RV dysfunction is a matter of interesting investigations,HFpEF is a complex disease at high and increasing prevalence with no effective therapeutic options. Among the pathophysiologic abnormalities that contribute to the heterogeneity of HFpEF syndrome, recent epidemiological and clinical studies have progressively focused on the RH, pointing out its basic role as a mediator of the progression of the disease, exhibiting a high prediction value for clinical worsening, and representing a main target of newly developed therapeutic opportunities. Several clinical RH phenotypes at rest and during physical challenge have been described, and the pathophysiology behind the different evolving stages is a matter of intriguing investigation. The main reason for the development of RH dysfunction is the augmented load imposed by the increased left atrial pressure associated with LV diastolic dysfunction and atrial myopathy, yielding to an increased pulsatile loading. The development of pulmonary vascular disease and wall remodeling further exacerbates the RH impedance through an increase in resistive load.The gold standard for measuring RH systolic function and its coupling with Pc are cardiac and vascular elastances measured by pressure-volume loops, but a number of echocardiography-derived parameters are alternatively used in daily practice for acquiring either functional and morphological information. Although these measures reflect, only in part, the complex hemodynamic adaptations of the RH, the functional assessment is now comprehensively approached through advanced imaging along with simplified method of RV-PC coupling. These indicators demonstrate a remarkable prognostic value starting from the earlier stages of the disease. Based on this evidence, most of the future research should focus on how the study of RH phenotypes could implement our knowledge on HFpEF.Upcoming research in the field should aim at a better understanding of the mechanisms involved in the RV geometric and functional progression starting from specific attention on the time-dependent changes in LA dynamics and deepest knowledge on the pathways involved in the lung vessel injury and remodeling processes.This study was supported by Monzino Fundation, Milano, Italy.None.


Echocardiography (2DE) is integral for screening and longitudinal evaluation of pulmonary arterial hypertension (PAH) in systemic sclerosis (SSc). In the present study, we sought to establish the reliability, repeatability, and reproducibility of 2DE parameters in SSc patients with and without PAH and to define the minimal detectable difference (MDD), the smallest change detected beyond measurement error.SSc patients without known PAH and with invasively confirmed PAH on stable therapies underwent 2DE with strain at two time points. Analysis of variance (ANOVA) and coefficients of variation (CV) were calculated to assess for repeatability, reliability, and reproducibility. Intra- and inter-observer agreement were assessed using intraclass correlation. Bland-Altman analysis explored the level of agreement between evaluations. MDD was calculated using the standard error of measurement for each parameter by cohort.ANOVA demonstrated few significant differences between evaluations across groups. Global right ventricular longitudinal systolic strain  and fractional area change  had the largest CV, while tricuspid annular plane excursion (TAPSE), S’ wave, and right ventricular outflow track velocity time integral (RVOT VTI) were 0.87%, 3.2%, and 6.0%, respectively. Intra- and inter-observer agreement was excellent. MDD for TAPSE, FAC, S’ wave, RVOT VTI, GRVLSS, and RVSP were 0.11 cm, 0.03%, 1.27 cm/s, 0.81 cm, 1.14%, and 6.5 mmHg, respectively.We demonstrate minimal measurement error in clinically important 2DE-based measures in SSc patients with and without PAH. Defining the MDD in this population has important implications for PAH screening, assessment of therapeutic response, and sample size calculations for future clinical trials.The online version contains supplementary material available at 10.1186/s13075-022-02835-5. Pulmonary arterial hypertension (PAH), a disease of the pulmonary vasculature that leads to right heart failure and death, commonly complicates systemic sclerosis (SSc) . Given iIn the present study, we sought to assess the performance of echocardiographic measures of RV function to assess the repeatability, reproducibility, and reliability of echo-derived measures of RV function and define the MDD. We hypothesized that TAPSE would have the least measurement error based upon our prior experience in SSc populations . This woOur study was approved by the Johns Hopkins Medicine Institutional Review Board. We prospectively enrolled prevalent SSc patients ≥18 years old from May 2017 to October 2018. All participants met the 1980  and/or 2Patients without evidence of resting PH or RV dysfunction by 2DE defined as resting RVSP < 35 mmHg and TAPSE ≥ 1.6 cm, FAC ≥ 35%, and tissue Doppler S’ ≥ 9.5 cm/s were recruited as cohort 1. Consecutive SSc patients with right heart catheterization (RHC)-proven PAH who were clinically stable on PAH-directed therapies were recruited as cohort 2. PAH was defined by a mean pulmonary artery pressure (mPAP) > 20 mmHg and pulmonary vascular resistance (PVR) > 3 Wood units (WU) with pulmonary artery wedge pressure ≤ 15 mmHg based on 2018 revised 6th World Symposium on Pulmonary Hypertension definition .Echocardiograms were performed using Canon Artida Ultrasound Machine  with subjects in the left lateral decubitus position during image acquisition at 70–90 frames per second at end-expiration. 2DE-directed methods to obtain linear and volumetric measurements of the RV chamber in accordance with American Society of Echocardiography (ASE) guidelines . Right a2DE echocardiographic measures were obtained by a single certified cardiac sonographer at two time points, evaluation A and evaluation B, separated by 1 h in a semi-fasting state, to limit biologic variability. Two echocardiographers, blinded to patient information, timing , and clinical variables performed 2DE analysis using Synapse Cardiovascular Software .STE-based longitudinal systolic strain analysis of the RV free wall was performed using commercially available strain software . From the 4-chamber apical view, peak systolic longitudinal strain of the RV free wall was obtained by tracing endocardial borders in end-systolic still frames and manually adjusted to ensure adequate border delineation and segment thickness . Peak loCategorical variables were expressed as absolute number and percentage. Continuous variables were expressed as mean ± standard deviation (SD) if normally distributed by the Shapiro-Wilk test and as median  if not normally distributed. To assess statistical differences in all echo measures between evaluation A and evaluation B, within disease group (cohort 1 and cohort 2), and overall, across both cohorts, ANOVA tests for normally distributed variables and Friedman tests for non-normally distributed variables were performed.t-tests or Mann-Whitney-Wilcoxon rank sum test as appropriate. Fisher exact test was used to analyze differences in categorical variables between cohorts. A P-value < 0.05 was considered as statistically significant.Comparisons between cohort 1 and cohort 2 were performed with independent sample All examinations were analyzed twice on two different days by the same physician (MM) blinded to cohort and timing of the echocardiogram to determine intraobserver agreement. Examinations were then analyzed by a second reader (VM), also blinded to cohort, timing, and previous interpretations to determine interobserver agreement.Repeatability, defined as the assessment of repeated measures on the same patient by the same operator on the same device under ideal conditions, was determined by calculating the SD for each patient between measurement A and B with a coefficient of variation (CV)  . Bland-AMDD, defined as the minimal change in a measurement that is greater than the within subject variability and measurement error, was calculated for individual subjects between the two different observations. MDD was calculated as standard error of the measurement (SEM) × 1.96 and is reported by cohort . SEM wasA total of 20 patients were included Table . Cohort All measures were obtained and available for interpretation and analysis, apart from one patient from cohort 2 with an inadequate TR Doppler signal. Severity of TR differed between cohorts, with 10% of cohort 1 with moderate or severe TR compared to 50% of cohort 2. Conventional 2DE and STE-derived data are described in Table P < 0.05) as shown in Table After determining normal distribution for both cohort 1 (SSc without known PAH) and cohort 2 (SSc-PAH), ANOVA was performed to compare measures between evaluation A and evaluation B for each subject within each cohort and demonstrated no significant differences in echocardiographic parameters of RV morphology and function between evaluations in both groups, with the exception of midventricular RVOT diameter, RVOT VTI, TR peak velocity, and RVSP , both FAC (CV 27.08%) and RVSP (48.61%) had CVs that exceed commonly used thresholds for acceptable variability of 15–20%, suggesting poor repeatability of these measures . Our dat2/m for indexed RV end-diastolic area; 4.7 ± 0.1% for FAC; and 0.08 ± 0.01 m/s for peak TR velocity [Prior studies in PAH populations (not solely comprised of SSc-PAH) have not routinely reported ICC as a measure of reproducibility or reliability; thus, direct comparison to these studies is challenging. Hinderliter et al. reported the reproducibility of select measures in a PAH population from a randomized controlled trial of epoprostenol by comparing the repeated interpretations of a selection of 17 baseline echocardiograms . The difvelocity . Similarvelocity . Unfortuvelocity , 37, 38,A key and novel component of the present study is the identification of the MDD for echocardiographic RV functional measures. Although not equivalent to the minimum clinically important difference, an MDD represents a key reference point upon which the lower bound of clinically relevant changes can be estimated , 40. TheThere are several limitations to the present study. First, the relatively small sample size may influence the robustness of the reported measurement characteristics and thus require confirmation in larger cohorts. However, we did perform bootstrap analyses of the MDD calculations to estimate a population MDD with confidence intervals. These analyses show that the bootstrap-estimated population MDD and our study sample MDD are similar and, importantly, that the confidence intervals are narrow and thus consistent with the presented estimates of MDD (Supplement Table In conclusion, these data on the variability of echo-based measures of RV function in SSc patients are highly relevant to the use and interpretation of these measures. The MDD for these measures offer an essential framework upon which estimation of clinically relevant changes can based to inform clinical decision-making, such as referral for RHC and escalation of therapies, not only in SSc but also in other forms of PAH. Further prospective studies are needed to establish the role of these echocardiographic measures in the management of SSc patients at-risk for and with known PAH and for patients with other forms of PAH.Additional file 1: Supplemental Table 1. Bootstrap estimated population minimal detectable differences for echocardiographic measurements.


This study aims to investigate the value of myocardial work (MW) parameters during the isovolumic relaxation (IVR) period in patients with left ventricular diastolic dysfunction (LVDD).This study prospectively recruited 448 patients with risks for LVDD and 95 healthy subjects. An additional 42 patients with invasive measurements of left ventricular (LV) diastolic function were prospectively included. The MW parameters during IVR were noninvasively measured using EchoPAC.IVR), myocardial constructive work during IVR (MCWIVR), myocardial wasted work during IVR (MWWIVR), and myocardial work efficiency during IVR (MWEIVR) of these patients were 122.5 ± 60.1 mmHg%, 85.7 ± 47.8 mmHg%, 36.7 ± 30.6 mmHg%, and 69.4 ± 17.8%, respectively. The MW during IVR was significantly different between patients and healthy subjects. For patients, MWEIVR and MCWIVR were significantly correlated with the LV E/e’ ratio and left atrial volume index, MWEIVR exhibited a significant correlation with the maximal rate of decrease in LV pressure (dp/dt per min) and tau, and the MWEIVR corrected by IVRT also exhibited a significant correlation with tau.The total myocardial work during IVR (MWMW during IVR significantly changes in patients with risks for LVDD, and is correlated to LV conventional diastolic indices, including dp/dt min and tau. Noninvasive MW during IVR may be a promising tool to evaluate the LV diastolic function.The online version contains supplementary material available at 10.1186/s12872-023-03156-4. Myocardial strain analysis has been validated as a reliable method for evaluating myocardial function. However, strain parameters are load dependent . MyocardThe diastolic assessment of the left ventricle (LV) remains challenging . In seveThe present study aims to investigate the value of measuring MW during IVR in patients with left ventricular diastolic dysfunction (LVDD). The hypothesis of measuring MW during IVR is a promising approach to assess the LV diastolic function.For the present study, 448 patients with risks for LVDD and 95 healthy subjects, who attended Beijing Hospital between October 2019 and August 2022, were consecutively included . The exclusion criteria were, as follows: (1) left ventricular ejection fraction (LVEF) of < 50%; (2) any pathological changes that could cause a pressure gradient between the aorta and left ventricle; (3) moderate or severe valvular heart disease; (4) arrhythmia, such as atrial fibrillation, supraventricular arrhythmias, left bundle branch block, etc.; (5) severe pulmonary, kidney, and/or liver disease; (6) the image quality for the speckle tracking analysis was poor.The risks for LVDD included hypertension (systolic and diastolic BP ≥ 140/90 mmHg), hypercholesterolaemia (fasting plasma low-density lipoprotein [LDL] cholesterol ≥ 160 mg/dL), diabetes mellitus (fasting plasma glucose ≥ 126 mg/dl and glycated hemoglobin level ≥ 6.5%), and/or obesity ; subjects not receiving medications; subjects without abnormal findings in the routine transthoracic echocardiography, based on the guidelines of the American Society of Echocardiography (ASE) . HealthyAn additional 42 patients, who received LV catheterization due to suspected CAD, were prospectively recruited. The invasive measurements included the maximal rate of decrease in LV pressure (dp/dt min), time constant of LV isovolumic pressure decline (tau), and left ventricular end diastolic pressure (LVEDP).The present study was approved by the institutional review board (IRB) (NCT03905200). All participants provided a signed informed consent.Echocardiography was conducted by experienced sonographers using the Vivid E95 ultrasound system . Images in cine loop format were analyzed offline using the EchoPAC software . All indices were measured according to ASE guidelines , 16. Pul2; (4) peak tricuspid regurgitation velocity of > 2.8 m/s. The patients were diagnosed, as follows: LVDD, when > 50% of the indexes met the above criteria; indeterminate LVDD, when merely 50% of the criteria were positive; with risk of developing LVDD but not LVDD yet, when < 50% of the indexes met the above criteria [2, average E/e’ > 14, or TR > 2.8 m/s); moderate, when E/A ≤ 0.8 and E > 50 cm/s or 0.8 < E/A < 2 + ≥ 2 positive criteria ; severe, when E/A ≥ 2. Based on the above two criteria, the patients in the present study were categorized into three subgroups: patients with risks for LVDD but without LVDD (n = 237), patients with indeterminate or mild LVDD (n = 113), and patients with moderate or severe LVDD (n = 98). Among these patients, three patients met the criteria for mild LVDD, and seven patients met the criteria for severe LVDD.According to the criteria of ASE , the cutcriteria . For patcriteria , 20, as In the EchoPAC software, the MW parameters were obtained through the pressure-strain loop (PSL) area module constructed from the curves for noninvasively estimated LV pressures and LV strains. The peak LV systolic pressure was assumed to be equal to the brachial cuff systolic BP measured during the echocardiographic study. This noninvasive method was validated by various research teams , 21, 22.IVR  = GCW—GSCW; MWWIVR  = GWW—GSWW. The total myocardial work during IVR (MWIVR) was obtained from the sum of MCWIVR and MWWIVR. Myocardial work efficiency during IVR (MWEIVR) was calculated, as follows: MCWIVR / (MCWIVR + MWWIVR) × 100%. The MWIVR parameters were normalized by dividing these by the corresponding IVRT.The MW parameters for ventricular systole were derived by entering the timings of the mitral valve closure and aortic valve closure . Global systolic constructive work (GSCW) was defined as the MW during shortening in systole, and global systolic wasted work (GSWW) was defined as the MW during lengthening in systole. The MW parameters specific for IVR were calculated through deduction: MCWA total of 42 patients, who underwent LV catheterization for coronary angiography, were prospectively included. The invasive LV pressure was recorded. The LV dp/dt min, tau and LVEDP were averaged over 3–6 cardiac cycles. An LVEDP value of > 16 mmHg was defined as an elevated LV filling pressure . The invt-test. The comparison of non-normally distributed variables was performed using Mann–Whitney U-test. Comparisons among three or more groups of continuous variables were analyzed using analysis of variance . X2 or Fisher’s exact test was used for categorical data comparisons. Pearson’s correlation was used to test the association between MW parameters during IVR, and clinical or conventional echocardiographic variables, or dp/dt min, tau and LVEDP. The intra- and inter-observer variabilities of the MW parameters during IVR were assessed using intraclass correlation coefficients (ICCs). P < 0.05 was considered statistically significant. The statistical analysis was conducted using the SPSS 23.0 software.Continuous variables with normal distribution were expressed as mean ± standard deviation (SD), or median (interquartile range) when the normal distribution was not confirmed. The comparison of normally distributed variables between two groups was performed using independent-sample P < 0.001). The levels of plasma brain natriuretic peptide (BNP) and uric acid were higher in the moderate or severe LVDD group, when compared to the levels in the other two patient groups (P < 0.005). There were no significant differences in the majority of the clinical and biochemical characteristics  among the patient groups (P > 0.05).The clinical and biochemical characteristics are presented in Table The echocardiographic indices for LV systolic and diastolic performance were significantly different among the patient groups Table . The PSDIVR, MCWIVR, MWWIVR and MWEIVR in healthy subjects are presented in Table IVR, MCWIVR and MWWIVR were significantly correlated with LV IVRT and systolic BP. Both MWIVR and MCWIVR were mildly correlated with the left atrial longitudinal strain during the conduit phase (LAScd). No significant correlations were found between the MW parameters during IVR, and age or heart rate.The values for MWIVR, MCWIVR and MWWIVR were significantly correlated with the IVRT. MWEIVR exhibited a mild correlation with the IVRT . MWIVR and MCWIVR were associated with age and systolic BP. The MW parameters during IVR exhibited weak or no correlations with most of the left atrial strain parameters and serum biochemical indicators. No significant correlation was found between MW parameters during the IVR period and heart rate. MWIVR and MCWIVR were significantly higher in patients with risk for LVDD but no confirmed LVDD, when compared to healthy subjects. MWIVR and MCWIVR reached the maximum in patients with indeterminate or mild LVDD, and these declined in patients with moderate or severe LVDD  for MWEIVR. The ICC for inter-observer variability was 0.85 (95% CI: 0.55–0.94) for MWIVR and 0.85 (95% CI: 0.70–0.92) for MWEIVR.The intra- and inter-observer variabilities were measured in 30 randomly selected subjects. The ICC for intra-observer variability was 0.85 (95% CI: 0.71–0.93) for MWIVR, moderately correlated with the invasively measured dp/dt min and tau.MW parameters during IVR are novel echocardiographic parameters derived from MW. The present study was the first to report on MW parameters during the IVR period. The investigators identified novel MW parameters during IVR, which were correlated with the LV diastolic dysfunction measured by conventional echocardiography. In addition, it was identified that MW-derived indices, especially MWEIVR, MCWIVR, MWWIVR and MWEIVR were not correlated with age or heart rate. These findings were different from the findings reported by Santoro et al. [., 65% of the patients were < 49 years old, while in the present study, 85.3% of the patients were < 49 years old. Furthermore, a study revealed that the levels of GCW, GWW and GWE were stable until the age of 45 years old. Thereafter, there was an upward shift to further stable values of GCW, and a linear increase in GWW with the advance of age, resulting in lower GWE [IVR parameters in the present study had very strong positive correlations with IVRT. This implies that the longer the IVR, the higher the total work of the myocardium.For the 95 healthy subjects, MWo et al. . In the ower GWE . The MW ower GWE , 28. ThiIVR (74.9 ± 13.7%) was significantly lower than the GWE analyzed during systole and IVRT (95.7 ± 2.3%). This suggests that there is a higher proportion of wasted MW during the IVR interval, when compared to that in systole. The shortening, which is waisted and included in the calculation of wasted MW in IVR, is also called, post-systolic shortening [Cardiac efficiency is the ratio between constructive work and total work (the sum of both constructive and wasted work). It was identified that in normal controls, MWEortening . Althougortening , 31. TheIVR and MCWIVR exhibited a dynamic pattern as the diastolic dysfunction progressed. This may limit its clinical application, since the MW values were lower in patients with moderate and severe LVDD, when compared to patients with indeterminate and mild LVDD. The significant correlation between these MW parameters and IVR duration was likely responsible for this pattern. As the left atrial pressure increased along with the diastolic dysfunction, the IVR was shortened after initially being prolonged [IVR and MCWIVR were normalized for IVRT time, these parameters no longer exhibited the dynamic pattern mentioned above as the diastolic dysfunction progressed. Among all the MW parameters, regardless of whether these were normalized or non-normalized, MWEIVR was better and not impacted by the dynamic pattern. As shown in Fig. IVR exhibited a unidirectional change as the diastolic dysfunction progressed, making it a good candidate for diagnosis, and stratifying the degree of diastolic dysfunction .Traditional LV diastolic function indices, such as septal and lateral e’, average E/e’ ratio and LAVI, are the recommended measurements for diastolic function analysis . Howeverrolonged . After Mr = 0.084, r = 0.029 and 0.032, respectively). Similar results were also reported by other studies [IVR is promising, since this was significantly associated with both tau (r = -0.503) and dp/dt min (r = 0.329). As the most established index to describe myocardial relaxation [IVR. LVEDP is an important measurement for ventricular filling pressure, which is impacted by both myocardial relaxation and myocardial stiffness [The noninvasive assessment of LV diastolic function remains challenging . The cor studies , 34. Baslaxation , the tautiffness , 37. ThiIVR parameters. However, further in-depth research on the dyssynchrony and contraction of myocardial fibers during IVRT is needed. Lastly, there were very few patients with mild and severe LVDD.The present study had some limitations that should be mentioned. The average age of the healthy subjects was significantly lower, when compared to the patient groups. However, there was no significant correlation between age and MW parameters during IVR in healthy subjects. Hence, the impact of age on the MW parameters may not be significant. In the present study, echocardiography and cardiac catheterization were not simultaneously performed. Therefore, the pressure data during the IVR period was derived based on estimation, affecting the reliability of the MW parameters. Furthermore, the role of ventricular dyssynchrony was not comprehensively evaluated in the present study. Increased ventricular afterload would impair early relaxation, and induce wall dyssynchrony. The present results revealed that there was a mild correlation between PSD and MWMW during IVR progresses along with the severity of LVDD, and has some correlation with LV invasive diastolic indices, including dp/dt min and tau. Noninvasive MW during IVR may be a promising tool to evaluate the LV diastolic function.Additional file 1:Supplementary Figure 1. Normalized MW parameters during IVR, compared across the different groups. Legend: IVR, isovolumic relaxation; LVDD, left ventricular diastolic dysfunction; MCWIVR, myocardial constructive work during IVR; MWIVR, total myocardial work during IVR; MWEIVR, myocardial work efficiency during IVR; MWWIVR, myocardial wasted work during IVR. Normalized MWIVR parameters, MWIVR parameters corrected by IVRT. *P<0.05, compared to healthy subjects.Additional file 2: Supplementary table 1. Associations between MW parameters during IVR, and clinical and echocardiographic variables in healthy subjects and patients. Supplementary table 2. Normalized MWIVR parameters for healthy subjects and patients. Supplementary table 3. Baseline characteristics of patients with invasive measures of diastolic function (n=42). Supplementary table 4. Correlations between invasive measures of other parameters (n=42).