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Highlights • Knowledge of the genetic etiologies of cardiomyopathies has created novel opportunities for treatments. • Emerging treatments targets include gene therapy, myofilament function, protein quality control, and metabolism. • Consideration of the genetic cause, biophysical context, and cardiomyopathy disease stage will be critical to the success of these novel treatments., Summary The primary etiology of a diverse range of cardiomyopathies is now understood to be genetic, creating a new paradigm for targeting treatments on the basis of the underlying molecular cause. This review provides a genetic and etiologic context for the traditional clinical classifications of cardiomyopathy, including molecular subtypes that may exhibit differential responses to existing or emerging treatments. The authors describe several emerging cardiomyopathy treatments, including gene therapy, direct targeting of myofilament function, protein quality control, metabolism, and others. The authors discuss advantages and disadvantages of these approaches and indicate areas of high potential for short- and longer term efficacy., Central Illustration

Objective: End stage heart failure is a lethal disease with a dismal 5 year survival. Heart transplantation has proven to be a highly effective modality of treatment in appropriately selected group of such patients. This is a retrospective analysis of medium term outcomes of heart transplantation in the setting of a private health facility in India. The objective of this study was two fold.1 1 To document the short term and medium term survival of patients undergoing a heart transplant procedure 2 To identify the risk factors for unfavorable outcomes with subgroup analysis. Methods: The outcome of 257 heart transplants done at a single centre from October 2012 to October 2019 was analyzed. Patients with combined Heart and lung transplants and those whose complete medical records were unavailable were excluded from the study. Survival was tracked at 60 days, 90 days, one year and beyond for a maximum of 7 years. Preoperative patient risk profiles were characterized on the basis of INTERMACS category. Results: There were 176 male and 81 female patients. The age range was from 8 months to 78 years with a mean of 32.9 years. Survival at 2 months was 87%, at 90 days was 83%, at one year was 81%, 2 years was 75%, at 3 years was 72% and at 5 years and beyond was 62% for the whole series. Strong predictors of 90 day mortality included INTERMACS category (odd's ratio 0.289, p = 0.000) and creatinine more than 1.5 mg/dl (odd's ratio 2.48, p = 0.056). Recipient pulmonary vascular resistance and donor organ ischemic times were not found to be statistically significant factors affecting outcome. Medium term survival was influenced by INTERMACS category (Hazard ratio > 3 for INTERMACS category 1 compared to INTERMACS 4 or 5, p 1.5 mg/dl (Hazard ratio 2.15, p = 0.003). This effect of creatinine was related to the age of the recipient. Hazard ratio 1.4, p = 0.524 if age 50. Conclusion: Satisfactory medium term outcome is possible after heart transplantation even in resource constrained environment of a developing country.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is rarely diagnosed in childhood. We describe the case of a 9-year-old girl with genetically confirmed ARVC who presented with syncope, ventricular arrhythmia, and biventricular myocardial dysfunction. This case highlights the need for development of pediatric ARVC diagnosis criteria specific for pediatric patients and discusses potential diagnostic improvement using echocardiographic deformation imaging. (Level of Difficulty: Beginner.), Graphical abstract, Arrhythmogenic right ventricular cardiomyopathy (ARVC) is rarely diagnosed in childhood. We describe the case of a 9-year-old girl with genetically…

We report a case of coronary artery compression and athlete's heart in a patient with a history of transposition of the great arteries. We present the diagnostic dilemmas and demonstrate the use of cardiac magnetic resonance imaging and cycle-ergometer stress cardiac magnetic resonance in the management of our patient. (Level of Difficulty: Intermediate.), Graphical abstract, We report a case of coronary artery compression and athlete's heart in a patient with a history of transposition of the great arteries. We present…

Background Hypertrophic cardiomyopathy (HCM) is caused by rare variants in sarcomere-encoding genes, but little is known about the clinical significance of these variants in the general population. Objectives The goal of this study was to compare lifetime outcomes and cardiovascular phenotypes according to the presence of rare variants in sarcomere-encoding genes among middle-aged adults. Methods This study analyzed whole exome sequencing and cardiac magnetic resonance imaging in UK Biobank participants stratified according to sarcomere-encoding variant status. Results The prevalence of rare variants (allele frequency, Central Illustration

Visual Abstract, Highlights • Patients with dilated cardiomyopathy who achieved LVRR have a favorable prognosis, but it is still difficult to precisely predict LVRR in the clinical setting. • Immunostaining of DNA damage markers such as PAR in biopsy specimens from patients with dilated cardiomyopathy revealed that patients with LVRR showed a significantly smaller proportion of PAR-positive nuclei compared with those without LVRR. • The high proportion of PAR-positive nuclei was an independent prognostic factor for LVRR. Besides, it can predict clinical prognosis (death, heart transplantation, and ventricular assist device implantation) with good sensitivity and specificity., Summary This study evaluated myocardial nuclear staining for the DNA damage markers poly(ADP-ribose) (PAR) and γ-H2A.X in 58 patients with dilated cardiomyopathy. Patients with left ventricular reverse remodeling (LVRR) showed a significantly smaller proportion of PAR-positive nuclei and γ-H2A.X–positive nuclei in biopsy specimens compared with those without LVRR. Propensity analysis showed that the proportion of both PAR-positive and γ-H2A.X–positive nuclei were independent prognostic factors for LVRR. In conclusion, we showed the utility of DNA damage-marker staining to predict the probability of LVRR, thus revealing a novel prognostic predictor of medical therapy for dilated cardiomyopathy.

Background: The objective is to study the molecular mechanism(s) underlying cardiac troponin I autoantibody (cTnIAAb) binding to cardiomyocyte and resultant myocardial damage/dysfunction. Methods: cTnIAAb was purified from serum of 10 acute myocardial infarction (AMI) patients with left ventricular remodeling. Recombinant human cTnI was used to generate three mouse-derived monoclonal anti-cTnI antibodies (cTnImAb1, cTnImAb2, and cTnImAb3). The target protein in cardiac myocyte membrane bound to cTnImAb and effect of cTnIAAb and cTnImAb on apoptosis and myocardial function were determined. Findings: We revealed that cTnIAAb/cTnImAb1 directly bound to the cardiomyocyte membraneI±-Enolase (ENO1) and triggered cell apoptosis via increased expression of ENO1 and Bax, decreased expression of Bcl2, subsequently activating Caspase8, Caspase 3, phosphatase and tensin homolog (PTEN) while inhibiting Akt activity. This cTnIAAb-ENO1-PTEN-Akt signaling axis contributed to increased myocardial apoptosis, myocardial collagen deposition, and impaired systolic dysfunction. Interpretation: cTnIAAb is not only the independent risk factor of ventricular remodeling after myocardial injury in patients with AMI, but also involved in the process of ventricular remodeling. Funding Statement: This research was supported by the National Natural Science Foundation of China (Grant#: 81260026) and the Doctoral Innovation Fund from Second military Medical University of China. Declaration of Interests: The authors state: "None." Ethics Approval Statement: This study was approved by the Medical Ethics Committee at Changhai Hospital and Changcheng Hospital Affiliated to Nanchang University and patients enrolled provided signed informed consent. The animal protocol was planned in compliance with the animal protection, animal welfare, and ethical principles and was approved by the IACUC of the Second Military Medical University.

Visual Abstract, Highlights • The homozygous c.38T>G mutation in the LEMD2 gene causes arrhythmic cardiomyopathy with bilateral juvenile cataract in the Hutterite population. • The cardiac phenotype is characterized by localized inferior and inferolateral fibrosis of the left ventricle and mild impairment of left ventricular systolic function but severe ventricular arrhythmias leading to sudden cardiac death. • Affected heart tissue and fibroblasts exhibit abnormally shaped nuclei with condensed peripheral heterochromatin. • Functional assays on affected fibroblasts show decreased proliferation capacity, cellular senescence, and a prolonged G1 phase, suggesting premature aging and cellular senescence in proliferating cells., Summary Nuclear envelope proteins have been shown to play an important role in the pathogenesis of inherited dilated cardiomyopathy. Here, we present a remarkable cardiac phenotype caused by a homozygous LEMD2 mutation in patients of the Hutterite population with juvenile cataract. Mutation carriers develop arrhythmic cardiomyopathy with mild impairment of left ventricular systolic function but severe ventricular arrhythmias leading to sudden cardiac death. Affected cardiac tissue from a deceased patient and fibroblasts exhibit elongated nuclei with abnormal condensed heterochromatin at the periphery. The patient fibroblasts demonstrate cellular senescence and reduced proliferation capacity, which may suggest an involvement of LEM domain containing protein 2 in chromatin remodeling processes and premature aging.

Objective: To the authors' knowledge, limited data are available regarding the association between Electrocardiogram (ECG) signs of right ventricular hypertrophy (RVH) and pulmonary hypertension (PH) in patients with dilated cardiomyopathy (DCM). We aimed to assess the accuracy of the recommended ECG criteria of RVH for predicting PH in patients with DCM. Methods: According to the definition of PH (mPAP ≥ 25 mm Hg), 35 patients with DCM were divided into 2 groups: DCM with PH (n = 22) and DCM without PH (n = 13). Right heart catheterization was performed in all patients. Seventeen parameters of RVH recommended by the AHA/ACCF/HRS for diagnosis of RVH on ECG were determinded. Results: The following parameters were correlated with mPAP: RV1 > 6 mm, SV5 > 10 mm, R:SV6 10.5 mm and PII amplitude. The following parameters were significantly different between DCM patients with and without PH: S in V5 (SV5) > 10 mm, S in V6 (SV6) > 3 mm, R:S ratio in V5 (R:SV5) 10.5 mm, S > R inI, S > R inII and R:S V1 > R:S V3, although results were no longer significant after correcting for multiple comparisons. High specificity (92.3–100%), lowsensitivity (31.8–50%), high positive predictive value, and low negative predictive value of established parameters of RVH were noted for predicting PH in patients with DCM. Conclusion: Several ECG signs of RVH may be useful for in the diagnosis PH in patients with DCM. Keywords: Dilated cardiomyopathy, Pulmonary hypertension, Right ventricular hypertrophy, ECG

Objectives The objective of this study was to determine the relationship between heart rate and relapse among patients in the TRED-HF (Therapy withdrawal in REcovered Dilated cardiomyopathy trial). Background Understanding markers and mechanisms of relapse among patients with recovered dilated cardiomyopathy (DCM) may enable personalized management. Methods The relationship between serial heart rate measurements and relapse was examined among patients in the TRED-HF trial, a randomized trial which examined the safety and feasibility of withdrawing heart failure therapy from 51 patients with recovered DCM over 6 months. In total, 25 patients were randomized to therapy withdrawal and 26 to continue therapy, of whom 25 subsequently began therapy withdrawal in a single arm crossover phase. Results The mean ± SD heart rate for those who had therapy withdrawn and did not relapse was 64.6 ± 10.7 beats/min at baseline and 74.7 ± 10.4 beats/min at follow-up, compared to 68.3 ± 11.3 beats/min at baseline and 86.1 ± 11.8 beats/min at follow-up for those who relapsed. After adjusting for differences in heart rate at baseline, patients who had therapy withdrawn and relapsed had a 10.4 beats/min (95% CI: 4.0–16.8) greater rise in heart rate than patients who had therapy withdrawn and did not relapse (P = 0.002). After data were adjusted for age, log N-terminal pro–B-type natriuretic peptide, and left ventricular ejection fraction (LVEF), heart rate (per 10 beats/min; hazard ratio [HR]: 1.65; 95% CI: 1.10-2.57; P = 0.01) and change in heart rate from baseline (per 10 beats/min; HR: 1.70; 95% CI: 1.12–2.57; p = 0.01) were associated with relapse. The results remained qualitatively the same after adjusting for beta-blocker dose. Conclusions For patients with DCM and improved LVEF, the rise in heart rate after treatment is withdrawn treatment identifies patients who are more likely to relapse. Whether the increase in heart rate is a marker or a mediator of relapse requires investigation. (Therapy withdrawal in REcovered Dilated cardiomyopathy trial [TRED]; NCT02859311), Central Illustration

Cardiac myosin-binding protein C (cMyBP-C) interacts with actin and myosin to modulate cardiac muscle contractility. These interactions are disfavored by cMyBP-C phosphorylation. Heart failure patients often display decreased cMyBP-C phosphorylation, and phosphorylation in model systems has been shown to be cardioprotective against heart failure. Therefore, cMyBP-C is a potential target for heart failure drugs that mimic phosphorylation or perturb its interactions with actin/myosin. Here we have used a novel fluorescence lifetime-based assay to identify small-molecule inhibitors of actin-cMyBP-C binding. Actin was labeled with a fluorescent dye (Alexa Fluor 568, AF568) near its cMyBP-C binding sites; when combined with the cMyBP-C N-terminal fragment, C0-C2, the fluorescence lifetime of AF568-actin decreases. Using this reduction in lifetime as a readout of actin binding, a high-throughput screen of a 1280-compound library identified three reproducible hit compounds (suramin, NF023, and aurintricarboxylic acid) that reduced C0-C2 binding to actin in the micromolar range. Binding of phosphorylated C0-C2 was also blocked by these compounds. That they specifically block binding was confirmed by an actin-C0-C2 time-resolved FRET (TR-FRET) binding assay. Isothermal titration calorimetry (ITC) and transient phosphorescence anisotropy (TPA) confirmed that these compounds bind to cMyBP-C, but not to actin. TPA results were also consistent with these compounds inhibiting C0-C2 binding to actin. We conclude that the actin-cMyBP-C fluorescence lifetime assay permits detection of pharmacologically active compounds that affect cMyBP-C-actin binding. We now have, for the first time, a validated high-throughput screen focused on cMyBP-C, a regulator of cardiac muscle contractility and known key factor in heart failure.

Actin–myosin mediated contractile forces are crucial for many cellular functions, including cell motility, cytokinesis, and muscle contraction. We determined the effects of ten actin-binding compounds on the interaction of cardiac myosin subfragment 1 (S1) with pyrene-labeled F-actin (PFA). These compounds, previously identified from a small-molecule high-throughput screen (HTS), perturb the structural dynamics of actin and the steady-state actin-activated myosin ATPase activity. However, the mechanisms underpinning these perturbations remain unclear. Here we further characterize them by measuring their effects on PFA fluorescence, which is decreased specifically by the strong binding of myosin to actin. We measured these effects under equilibrium and steady-state conditions, and under transient conditions, in stopped-flow experiments following addition of ATP to S1-bound PFA. We observed that these compounds affect early steps of the myosin ATPase cycle to different extents. They increased the association equilibrium constant K1 for the formation of the strongly bound collision complex, indicating increased ATP affinity for actin-bound myosin, and decreased the rate constant k+2 for subsequent isomerization to the weakly bound ternary complex, thus slowing the strong-to-weak transition that actin–myosin interaction undergoes early in the ATPase cycle. The compounds' effects on actin structure allosterically inhibit the kinetics of the actin–myosin interaction in ways that may be desirable for treatment of hypercontractile forms of cardiomyopathy. This work helps to elucidate the mechanisms of action for these compounds, several of which are currently used therapeutically, and sets the stage for future HTS campaigns that aim to discover new drugs for treatment of heart failure.

The study of extracellular phosphorylation was initiated in late 19th century when the secreted milk protein, casein, and egg-yolk protein, phosvitin, were shown to be phosphorylated. However, it took more than a century to identify Fam20C, which phosphorylates both casein and phosvitin under physiological conditions. This kinase, along with its family members Fam20A and Fam20B, defined a new family with altered amino acid sequences highly atypical from the canonical 540 kinases comprising the kinome. Fam20B is a glycan kinase that phosphorylates xylose residues and triggers peptidoglycan biosynthesis, a role conserved from sponges to human. The protein kinase, Fam20C, conserved from nematodes to humans, phosphorylates well over 100 substrates in the secretory pathway with overall functions postulated to encompass endoplasmic reticulum homeostasis, nutrition, cardiac function, coagulation, and biomineralization. The preferred phosphorylation motif of Fam20C is SxE/pS, and structural studies revealed that related member Fam20A allosterically activates Fam20C by forming a heterodimeric/tetrameric complex. Fam20A, a pseudokinase, is observed only in vertebrates. Loss-of-function genetic alterations in the Fam20 family lead to human diseases such as amelogenesis imperfecta, nephrocalcinosis, lethal and nonlethal forms of Raine syndrome with major skeletal defects, and altered phosphate homeostasis. Together, these three members of the Fam20 family modulate a diverse network of secretory pathway components playing crucial roles in health and disease. The overarching theme of this review is to highlight the progress that has been made in the emerging field of extracellular phosphorylation and the key roles secretory pathway kinases play in an ever-expanding number of cellular processes.

We describe the successful retrieval of a novel large mitral clip, which embolized in a patient with severe secondary mitral regurgitation and left ventricular dysfunction, dilated left ventricle, and severely tethered mitral valve leaflets in the setting of a challenging anatomy for transcatheter edge-to-edge repair. The description highlights planning, technical issues, and possible adverse events of this bailout procedure. (Level of Difficulty: Intermediate.), Central Illustration

Objectives The purpose of this study was to identify where ultrasmall superparamagnetic particles of iron oxide (USPIO) locate to in myocardium, develop a methodology that differentiates active macrophage uptake of USPIO from passive tissue distribution; and investigate myocardial inflammation in cardiovascular diseases. Background Myocardial inflammation is hypothesized to be a key pathophysiological mechanism of heart failure (HF), but human evidence is limited, partly because evaluation is challenging. USPIO-magnetic resonance imaging (MRI) potentially allows specific identification of myocardial inflammation but it remains unclear what the USPIO-MRI signal represents. Methods Histological validation was performed using a murine acute myocardial infarction (MI) model. A multiparametric, multi-time-point MRI methodology was developed, which was applied in patients with acute MI (n = 12), chronic ischemic cardiomyopathy (n = 7), myocarditis (n = 6), dilated cardiomyopathy (n = 5), and chronic sarcoidosis (n = 5). Results USPIO were identified in myocardial macrophages and myocardial interstitium. R1 time-course reflected passive interstitial distribution whereas multi-time-point R2* was also sensitive to active macrophage uptake. R2*/R1 ratio provided a quantitative measurement of myocardial macrophage infiltration. R2* behavior and R2*/R1 ratio were higher in infarcted (p = 0.001) and remote (p = 0.033) myocardium in acute MI and in chronic ischemic cardiomyopathy (infarct: p = 0.008; remote p = 0.010), and were borderline higher in DCM (p = 0.096), in comparison to healthy controls, but were no different in myocarditis or sarcoidosis. An R2*/R1 threshold of 25 had a sensitivity and specificity of 90% and 83%, respectively, for detecting active USPIO uptake. Conclusions USPIO are phagocytized by cardiac macrophages but are also passively present in myocardial interstitium. A multiparametric multi-time-point MRI methodology specifically identifies active myocardial macrophage infiltration. Persistent active macrophage infiltration is present in infarcted and remote myocardium in chronic ischemic cardiomyopathy, providing a substrate for HF., Central Illustration

Post-transcriptional regulation of mRNA translation and stability is primarily achieved by RNA-binding proteins, which are of increasing importance for heart function. Furthermore, G-quadruplex (G4) and G4 resolvase activity are involved in a variety of biological processes. However, the role of G4 resolvase activity in heart function remains unknown. The present study aims to investigate the role of RNA helicase associated with adenylate- and uridylate-rich element (RHAU), an RNA-binding protein with G4 resolvase activity in postnatal heart function through deletion of Rhau in the cardiomyocytes of postnatal mice. RHAU-deficient mice displayed progressive pathological remodeling leading to heart failure and mortality and impaired neonatal heart regeneration. RHAU ablation reduced the protein levels but enhanced mRNA levels of Yap1 and Hexim1 that are important regulators for heart development and postnatal heart function. Furthermore, RHAU was found to associate with both the 5' and 3' UTRs of these genes to destabilize mRNA and enhance translation. Thus, we have demonstrated the important functions of RHAU in the dual regulation of mRNA translation and stability, which is vital for heart physiology.

Background Adriamycin-associated cardiomyopathy (ACM) can lead to end-stage heart failure requiring advanced heart failure therapies. Objectives This study sought to provide post–cardiac transplant survival data in patients with ACM in the contemporary era of mechanical circulatory support and cardiac transplantation. Methods Adults (≥18 years of age) who underwent first-time, single-organ heart transplantation were identified from the United Network for Organ Sharing between October 18, 2008, and October 18, 2018. Cardiomyopathy subtypes that could have been supported with a left ventricular assist device (LVAD) including ACM, dilated cardiomyopathy (DCM), and ischemic cardiomyopathy (ICM) were included. A multivariable Cox regression analysis was performed to determine the association between cardiomyopathy subtype and post–cardiac transplant survival. Results This analysis included 18,270 patients (357 with ACM; 10,662 with DCM; and 7,251 with ICM). Heart transplant recipients with ACM were younger, included more women, and had higher pulmonary vascular resistance at the time of listing. Patients with ACM had a lower percentage of durable LVADs at the time of transplant across all years of the study period. Patients with ACM did not experience an increase in post–cardiac transplant mortality compared to those with DCM (adjusted hazard ratio: 0.96; 95% confidence interval: 0.79 to 1.40; p = 0.764) or ICM (adjusted hazard ratio: 0.85; 95% confidence interval: 0.6 to 1.2; p = 0.304). Conclusions Patients with ACM who received heart transplants between 2008 and 2018 had similar post–cardiac transplant survival to those with dilated and ischemic cardiomyopathy. Bridge-to-transplant LVAD use remains lower compared to other cardiomyopathy subtypes., Central Illustration

The progression of cardiovascular research is often impeded by the lack of reliable disease models that fully recapitulate the pathogenesis in humans. These limitations apply to both in vitro models such as cell-based cultures and in vivo animal models which invariably are limited to simulate the complexity of cardiovascular disease in humans. Implementing human heart tissue in cardiovascular research complements our research strategy using preclinical models. We established the Human Explanted Heart Program (HELP) which integrates clinical, tissue and molecular phenotyping thereby providing a comprehensive evaluation into human heart disease. Our collection and storage of biospecimens allow them to retain key pathogenic findings while providing novel insights into human heart failure. The use of human non-failing control explanted hearts provides a valuable comparison group for the diseased explanted hearts. Using HELP we have been able to create a tissue repository which have been used for genetic, molecular, cellular, and histological studies. This review describes the process of collection and use of explanted human heart specimens encompassing a spectrum of pediatric and adult heart diseases, while highlighting the role of these invaluable specimens in translational research. Furthermore, we highlight the efficient procurement and bio-preservation approaches ensuring analytical quality of heart specimens acquired in the context of heart donation and transplantation., Graphical abstract Illustration of the Human Explanted Heart Program (HELP) pathway as an integrative program that brings together clinicians and researchers aiming to unravel the underpinnings of cardiovascular disease and discover novel therapeutics. Our biobank contains tissue collections covering all sections of the explanted heart. A comprehensive review of the research participant clinical profile is also integrated into the analysis while complementary academic partnerships enabled us to broaden and diversify our approach to human heart disease.Unlabelled Image, Highlights • HELP - the largest research-integrated human heart transplant platform in Canada • Sizable specimen inventory of HELP enables research on a spectrum of heart diseases. • Systematic review of the methodology for HELP biobank management • Detailed evaluation on use of human hearts in translational cardiovascular medicine

Background Subcellular localization and function of L-type calcium channels (LTCCs) play an important role in regulating contraction of cardiomyocytes. Understanding how this is affected by the disruption of transverse tubules during heart failure could lead to new insights into the disease. Methods Cardiomyocytes were isolated from healthy donor hearts, as well as from patients with cardiomyopathies and with left ventricular assist devices. Scanning ion conductance and confocal microscopy was used to study membrane structures in the cells. Super-resolution scanning patch-clamp was used to examine LTCC function in different microdomains. Computational modeling predicted the impact of these changes to arrhythmogenesis at the whole-heart level. Findings We showed that loss of structural organization in failing myocytes leads to re-distribution of functional LTCCs from the T-tubules to the sarcolemma. In ischemic cardiomyopathy, the increased LTCC open probability in the T-tubules depends on the phosphorylation by protein kinase A, whereas in dilated cardiomyopathy, the increased LTCC opening probability in the sarcolemma results from enhanced phosphorylation by calcium-calmodulin kinase II. LVAD implantation corrected LTCCs pathophysiological activity, although it did not improve their distribution. Using computational modeling in a 3D anatomically-realistic human ventricular model, we showed how LTCC location and activity can trigger heart rhythm disorders of different severity. Interpretation Our findings demonstrate that LTCC redistribution and function differentiate between disease aetiologies. The subcellular changes observed in specific microdomains could be the consequence of the action of distinct protein kinases. Funding This work was supported by NIH grant (ROI-HL 126802 to NT-JG) and British Heart Foundation (grant RG/17/13/33173 to JG, project grant PG/16/17/32069 to RAC). Funders had no role in study design, data collection, data analysis, interpretation, writing of the report

The composition and the stiffness of cardiac microenvironment change during development and/or in heart disease. Cardiomyocytes (CMs) and their progenitors sense these changes, which decides over the cell fate and can trigger CM (progenitor) proliferation, differentiation, de-differentiation or death. The field of mechanobiology has seen a constant increase in output that also includes a wealth of new studies specific to cardiac or cardiomyocyte mechanosensing. As a result, mechanosensing and transduction in the heart is increasingly being recognised as a main driver of regulating the heart formation and function. Recent work has for instance focused on measuring the molecular, physical and mechanical changes of the cellular environment - as well as intracellular contributors to the passive stiffness of the heart. On the other hand, a variety of new studies shed light into the molecular machinery that allow the cardiomyocytes to sense these properties. Here we want to discuss the recent work on this topic, but also specifically focus on how the different components are regulated at various stages during development, in health or disease in order to highlight changes that might contribute to disease progression and heart failure., Highlights • The stiffness of the heart changes during development or in disease. • These changes influence cardiomyocyte behaviour and function. • Various intra- and extracellular elements contribute to the stiffness. • The molecules and pathways that are sensing the stiffness are changing as well.

Background We present the care of 17 consecutive pregnant patients who required mechanical ventilation for Coronavirus disease 2019 (COVID-19) pneumonia at a quaternary referral center in the United States. We retrospectively describe the management of these patients, maternal and fetal outcomes, as well as the feasibility of prone positioning and delivery. Methods Between March 2020 and June 2021, all pregnant and postpartum patients who were mechanically ventilated for COVID-19 pneumonia were identified. Details of their management including prone positioning, maternal and neonatal outcomes, and complications were noted. Results Seventeen pregnant patients required mechanical ventilation for COVID-19. Thirteen patients received prone positioning, with a total of 49 prone sessions. One patient required extracorporeal membrane oxygenation. All patients in this series survived until at least discharge. Nine patients delivered while mechanically ventilated, and all neonates survived, subsequently testing negative for SARS-CoV-2. There was one spontaneous abortion. Four emergent cesarean deliveries were prompted by refractory maternal hypoxemia or non-reassuring fetal heart rate after maternal intubation. Conclusions Overall, maternal and neonatal survival were favorable even in the setting of severe COVID-19 pneumonia requiring mechanical ventilation. Prone positioning was well tolerated although the impact of prone positioning or fetal delivery on maternal oxygenation and ventilation are unclear.

Visual Abstract, Highlights • Many cardiomyopathy families have genetic variants whose significance is unknown. We studied a novel (E848G) mutation in MYH7, a sarcomeric protein. • Patient-specific induced pluripotent stem cell–derived cardiomyocytes and engineered heart tissues recapitulated the contractile dysfunction. • Overexpression of the E848G allele in MYH7-null induced pluripotent stem cell–derived cardiomyocytes confirms the causality of the E848G variant. • The E848G allele disrupts the protein–protein interaction between MYH7 and cardiac myosin binding protein C, presenting a potential mechanism of action. • Assessing the pathogenicity of new MYH7 variants by overexpressing them in a null background should accelerate their screening for disease causality., Summary A novel myosin heavy chain 7 mutation (E848G) identified in a familial cardiomyopathy was studied in patient-specific induced pluripotent stem cell–derived cardiomyocytes. The cardiomyopathic human induced pluripotent stem cell–derived cardiomyocytes exhibited reduced contractile function as single cells and engineered heart tissues, and genome-edited isogenic cells confirmed the pathogenic nature of the E848G mutation. Reduced contractility may result from impaired interaction between myosin heavy chain 7 and cardiac myosin binding protein C.

Until recently considered as rare, circular RNAs (circRNAs) are emerging as important regulators of gene expression. They are ubiquitously expressed and represent a novel branch of the family of non-coding RNAs. Recent investigations showed that circRNAs are regulated in the cardiovascular system and participate in its physiological and pathological development. In this review article, we will provide an overview of the role of circRNAs in cardiovascular health and disease. After a description of the biogenesis of circRNAs, we will summarize what is known of the expression, regulation and function of circRNAs in the cardiovascular system. We will then address some technical aspects of circRNAs research, discussing how artificial intelligence may aid in circRNAs research. Finally, the potential of circRNAs as biomarkers of cardiovascular disease will be addressed and directions for future research will be proposed. Keywords: Non-coding RNAs, Circular RNAs, Cardiovascular system, Cardiovascular disease, Artificial intelligence, Biomarker

Epidermolysis bullosa simplex (EBS) is a rare inherited blistering disease characterized by mutations in several genes encoding for structural proteins within the epidermis. Mutations in kelch-like protein 24 (KLHL24) were recently implicated in a unique subtype of EBS.1 Features of EBS-KLHL24 include blistering at birth, stellate scarring, hypo- and hyperpigmentation in childhood, nail dystrophy, alopecia, anetoderma, and skin fragility. There is a growing association of dilated cardiomyopathy in EBS-KLHL24 that may be severe and present in early adulthood.2 Here we report a case to support the current evidence of dilated cardiomyopathy (DCM) associated with EBS-KLHL24. In addition, we report a successful orthotopic heart transplant (OHT) as treatment for severe manifestation of KLHL24 mutation–related cardiomyopathy.

Cardiac myosin is the molecular motor that powers heart contraction by converting chemical energy from ATP hydrolysis into mechanical force. The power output of the heart is tightly regulated to meet the physiological needs of the body. Recent multiscale studies spanning from molecules to tissues have revealed complex regulatory mechanisms that fine-tune cardiac contraction, in which myosin not only generates power output but also plays an active role in its regulation. Thus, myosin is both shaped by and actively involved in shaping its mechanical environment. Moreover, these studies have shown that cardiac myosin-generated tension affects physiological processes beyond muscle contraction. Here, we review these novel regulatory mechanisms, as well as the roles that myosin-based force generation and mechanotransduction play in development and disease. We describe how key intra- and intermolecular interactions contribute to the regulation of myosin-based contractility and the role of mechanical forces in tuning myosin function. We also discuss the emergence of cardiac myosin as a drug target for diseases including heart failure, leading to the discovery of therapeutics that directly tune myosin contractility. Finally, we highlight some of the outstanding questions that must be addressed to better understand myosin's functions and regulation, and we discuss prospects for translating these discoveries into precision medicine therapeutics targeting contractility and mechanotransduction.

Summary Heart failure (HF) is the end-stage of all heart disease and arguably constitutes the greatest unmet therapeutic need in cardiovascular medicine today. Classic epidemiological studies have established clinical risk factors for HF, but the cause remains poorly understood in many cases. Biochemical analyses of small case-control series and animal models have described a plethora of molecular characteristics of HF, but a single unifying pathogenic theory is lacking. Heart failure appears to result not only from cardiac overload or injury but also from a complex interplay among genetic, neurohormonal, metabolic, inflammatory, and other biochemical factors acting on the heart. Recent development of robust, high-throughput tools in molecular biology provides opportunity for deep molecular characterization of population-representative cohorts and HF cases (molecular epidemiology), including genome sequencing, profiling of myocardial gene expression and chromatin modifications, plasma composition of proteins and metabolites, and microbiomes. The integration of such detailed information holds promise for improving understanding of HF pathophysiology in humans, identification of therapeutic targets, and definition of disease subgroups beyond the current classification based on ejection fraction which may benefit from improved individual tailoring of therapy. Challenges include: 1) the need for large cohorts with deep, uniform phenotyping; 2) access to the relevant tissues, ideally with repeated sampling to capture dynamic processes; and 3) analytical issues related to integration and analysis of complex datasets. International research consortia have formed to address these challenges and combine datasets, and cohorts with up to 1 million participants are being collected. This paper describes the molecular epidemiology of HF and provides an overview of methods and tissue types and examples of published and ongoing efforts to systematically evaluate molecular determinants of HF in human populations., Central Illustration

Background: Both native T1 time and extracellular volume (ECV) fraction have been shown to be important measures for the detection of myocardial fibrosis. However, ECV determination requires the administration of an intravenous contrast agent, whereas native T1 mapping can be performed without a contrast agent. Methods: Here, we conducted a meta-analysis of myocardial native T1 data obtained for non-ischemic cardiomyopathy (NIC) patients and controls. A literature review included studies that applied T1 mapping using modified Look–Locker inversion recovery to measure myocardial fibrosis, and the results were validated by comparing datasets for dilated cardiomyopathy (DCM) or hypertrophic cardiomyopathy (HCM) patients and healthy controls (HCs). Results: We identified 16 eligible studies. Pooled mean differences (MDs) and 95% confidence intervals (CIs) were estimated as follows. Native T1 at 1.5-T, DCM vs. HC: MD = 45.26 (95% CI: 30.92–59.59); HCM vs. HC: MD = 47.09 (95% CI: 32.42–61.76). Native T1 at 3.0-T, DCM vs. HC: MD = 82.52 (95% CI: 47.60–117.44); HCM vs. HC: MD = 115.87 (95% CI: 50.71–181.04). ECV at 1.5-T, DCM vs. HC: MD = 4.26 (95% CI: 3.06–5.46); HCM vs. HC: MD = 1.49 (95% CI: −1.45–4.43). ECV at 3.0-T, DCM vs. HC: MD = 8.40 (95% CI: 2.94–13.86); HCM vs. HC: MD = 8.02 (95% CI: 5.45–1–0.59). Conclusion: In conclusion, native T1 values were significantly different between NIC patients and controls. Native T1 mapping may be a useful noninvasive method to detect diffuse myocardial fibrosis in NIC patients. Keywords: Native T1 mapping, Extracellular volume fraction, Dilated cardiomyopathy, Hypertrophic cardiomyopathy, Systematic review, Meta-analysis

Objectives This study was designed to analyze the prevalence and potential genetic basis of cancer and heart failure in peripartum cardiomyopathy (PPCM). Background PPCM manifests as heart failure late in pregnancy or postpartum in women without previous heart disease. Methods Clinical history and cancer prevalence were evaluated in a cohort of 236 PPCM patients from Germany and Sweden. Exome sequencing assessed variants in 133 genes associated with cancer predisposition syndromes (CPS) and in 115 genes associated with dilated/hypertrophic cardiomyopathy (DCM/HCM) in 14 PPCM patients with a history of cancer, and in 6 PPCM patients without a history of cancer. Results The prevalence of cancer was 16-fold higher (8.9%, 21 of 236 patients) in PPCM patients compared to age-matched women (German cancer registry, Robert-Koch-Institute: 0.59%; p < 0.001). Cancer before PPCM occurred in 12 of 21 patients of whom 11 obtained cardiotoxic cancer therapies. Of those, 17% fully recovered cardiac function by 7 ± 2 months of follow-up compared to 55% of PPCM patients without cancer (p = 0.015). Cancer occurred after PPCM in 10 of 21 patients; 80% had left ventricular ejection fraction of ≥50% after cancer therapy. Whole-exome sequencing in 14 PPCM patients with cancer revealed that 43% (6 of 14 patients) carried likely pathogenic (Class IV) or pathogenic (Class V) gene variants associated with DCM/HCM in CPT2, DSP, MYH7, TTN, and/or with CPS in ATM, ERCC5, NBN, RECQL4, and SLX4. All CPS variants affected DNA damage response genes. Conclusions Cardiotoxic cancer therapy before PPCM is associated with delayed full recovery. The high cancer prevalence in PPCM is linked to likely pathogenic/pathogenic gene variants associated with DCM/HCM and/or CPS/DNA damage response–related cancer risk. This may warrant genetic testing and screening for heart failure in pregnant women with a cancer history and screening for cancer in PPCM patients., Central Illustration

Cardiovascular disease (CVD) remains the most common cause of adult morbidity and mortality in developed nations. As a result, predisposition for CVD is increasingly important to understand. Ankyrins are intracellular proteins required for the maintenance of membrane domains. Canonical ankyrin-G (AnkG) has been shown to be vital for normal cardiac function, specifically cardiac excitability, via targeting and regulation of the cardiac voltage-gated sodium channel. Noncanonical (giant) AnkG isoforms play a key role in neuronal membrane biogenesis and excitability, with evidence for human neurologic disease when aberrant. However, the role of giant AnkG in cardiovascular tissue has yet to be explored. Here, we identify giant AnkG in the myocardium and identify that it is enriched in 1-week-old mice. Using a new mouse model lacking giant AnkG expression in myocytes, we identify that young mice displayed a dilated cardiomyopathy phenotype with aberrant electrical conduction and enhanced arrhythmogenicity. Structural and electrical dysfunction occurred at 1 week of age, when giant AnkG was highly expressed and did not appreciably change in adulthood until advanced age. At a cellular level, loss of giant AnkG results in delayed and early afterdepolarizations. However, surprisingly, giant AnkG cKO myocytes display normal INa, but abnormal myocyte contractility, suggesting unique roles of the large isoform in the heart. Finally, transcript analysis provided evidence for unique pathways that may contribute to the structural and electrical findings shown in giant AnkG cKO animals. In summary, we identify a critical role for giant AnkG that adds to the diversity of ankyrin function in the heart.

Inherited arrhythmias, such as cardiomyopathies and cardiac ion channelopathies, along with coronary heart disease (CHD) are three most common disorders that predispose adults to sudden cardiac death. In the last three decades, causal genes in inherited arrhythmias have been successfully identified. At the same time, it has become evident that the genetic architectures are more complex than previously known. Recent advancements in DNA sequencing technology (next generation sequencing) have enabled us to study such complex genetic traits. This article discusses indications for genetic testing of patients with inherited arrhythmias. Further, it describes the benefits and challenges that we face in the era of next generation sequencing. Finally, it briefly discusses genetic counseling, in which a multidisciplinary approach is required due to the increased complexity of the genetic information related to inherited arrhythmias. (C) 2016 Japanese Heart Rhythm Society. Published by Elsevier B.V

Cardiac resynchronisation therapy (CRT) is an established treatment for heart failure, however the effective selection of patients and optimisation of therapy remain controversial. While extensive research is ongoing, it remains unclear whether improvements in patient selection or therapy planning offers a greater opportunity for the improvement of clinical outcomes. This computational study investigates the impact of both physiological conditions that guide patient selection and the optimisation of pacing lead placement on CRT outcomes. A multi-scale biophysical model of cardiac electromechanics was developed and personalised to patient data in three patients. These models were separated into components representing cardiac anatomy, pacing lead location, myocardial conductivity and stiffness, afterload, active contraction and conduction block for each individual, and recombined to generate a cohort of 648 virtual patients. The effect of these components on the change in total activation time of the ventricles (ΔTAT) and acute haemodynamic response (AHR) was analysed. The pacing site location was found to have the largest effect on ΔTAT and AHR. Secondary effects on ΔTAT and AHR were found for functional conduction block and cardiac anatomy. The simulation results highlight a need for a greater emphasis on therapy optimisation in order to achieve the best outcomes for patients., Highlights • Ventricular conduction block indicates patient response to CRT. • Placement of CRT pacing leads strongly affects response to therapy. • Improved treatment planning should be prioritised in order to maximise CRT outcomes.

Background Improved understanding of dilated cardiomyopathy (DCM) due to titin truncation (TTNtv) may help guide patient stratification. Objectives The purpose of this study was to establish relationships among TTNtv genotype, cardiac phenotype, and outcomes in DCM. Methods In this prospective, observational cohort study, DCM patients underwent clinical evaluation, late gadolinium enhancement cardiovascular magnetic resonance, TTN sequencing, and adjudicated follow-up blinded to genotype for the primary composite endpoint of cardiovascular death, and major arrhythmic and major heart failure events. Results Of 716 subjects recruited (mean age 53.5 ± 14.3 years; 469 men [65.5%]; 577 [80.6%] New York Heart Association function class I/II), 83 (11.6%) had TTNtv. Patients with TTNtv were younger at enrollment (49.0 years vs. 54.1 years; p = 0.002) and had lower indexed left ventricular mass (5.1 g/m2 reduction; padjusted = 0.03) compared with patients without TTNtv. There was no difference in biventricular ejection fraction between TTNtv+/− groups. Overall, 78 of 604 patients (12.9%) met the primary endpoint (median follow-up 3.9 years; interquartile range: 2.0 to 5.8 years), including 9 of 71 patients with TTNtv (12.7%) and 69 of 533 (12.9%) without. There was no difference in the composite primary outcome of cardiovascular death, heart failure, or arrhythmic events, for patients with or without TTNtv (hazard ratio adjusted for primary endpoint: 0.92 [95% confidence interval: 0.45 to 1.87]; p = 0.82). Conclusions In this large, prospective, genotype-phenotype study of ambulatory DCM patients, we show that prognostic factors for all-cause DCM also predict outcome in TTNtv DCM, and that TTNtv DCM does not appear to be associated with worse medium-term prognosis., Central Illustration

The protein kinase C (PKC) and closely related protein kinase N (PKN) families of serine/threonine protein kinases play crucial cellular roles. Both kinases belong to the AGC subfamily of protein kinases that also include the cAMP dependent protein kinase (PKA), protein kinase B (PKB/AKT), protein kinase G (PKG) and the ribosomal protein S6 kinase (S6K). Involvement of PKC family members in heart disease has been well documented over the years, as their activity and levels are mis-regulated in several pathological heart conditions, such as ischemia, diabetic cardiomyopathy, as well as hypertrophic or dilated cardiomyopathy. This review focuses on the regulation of PKCs and PKNs in different pathological heart conditions and on the influences that PKC/PKN activation has on several physiological processes. In addition, we discuss mechanisms by which PKCs and the closely related PKNs are activated and turned-off in hearts, how they regulate cardiac specific downstream targets and pathways, and how their inhibition by small molecules is explored as new therapeutic target to treat cardiomyopathies and heart failure.

Visual Abstract, Highlights • SMAD4 is the central intracellular mediator of TGF-β pathway. • CM-specific loss of SMAD4 causes cardiac dysfunction independent of fibrotic remodeling. • Deletion CM-SMAD4 affects CM survival. • CM-SMAD4 loss leads to down-regulation of several ion channels’ genes, resulting in cardiac conduction abnormalities. • CM-SMAD4 deletion alters sarcomere shortening kinetics, in parallel with reduction in cardiac myosin-binding protein C levels. • These results demonstrate a fundamental role for CM-SMAD4–dependent TGF-β signaling in adult heart homeostasis., Summary The role of the transforming growth factor (TGF)-β pathway in myocardial fibrosis is well recognized. However, the precise role of this signaling axis in cardiomyocyte (CM) biology is not defined. In TGF-β signaling, SMAD4 acts as the central intracellular mediator. To investigate the role of TGF-β signaling in CM biology, the authors deleted SMAD4 in adult mouse CMs. We demonstrate that CM-SMAD4–dependent TGF-β signaling is critical for maintaining cardiac function, sarcomere kinetics, ion-channel gene expression, and cardiomyocyte survival. Thus, our findings raise a significant concern regarding the therapeutic approaches that rely on systemic inhibition of the TGF-β pathway for the management of myocardial fibrosis.

Objectives This study sought to investigate the association between the extent, location, and pattern of late gadolinium enhancement (LGE) and outcome in a large dilated cardiomyopathy (DCM) cohort. Background The relationship between LGE and prognosis in DCM is incompletely understood. Methods The authors examined the association between LGE and all-cause mortality and a sudden cardiac death (SCD) composite based on the extent, location, and pattern of LGE in DCM. Results Of 874 patients (588 men, median age 52 years) followed for a median of 4.9 years, 300 (34.3%) had nonischemic LGE. Estimated adjusted hazard ratios for patients with an LGE extent of 0 to 2.55%, 2.55% to 5.10%, and >5.10%, respectively, were 1.59 (95% confidence interval [CI]: 0.99 to 2.55), 1.56 (95% CI: 0.96 to 2.54), and 2.31 (95% CI: 1.50 to 3.55) for all-cause mortality, and 2.79 (95% CI: 1.42 to 5.49), 3.86 (95% CI: 2.09 to 7.13), and 4.87 (95% CI: 2.78 to 8.53) for the SCD endpoint. There was a marked nonlinear relationship between LGE extent and outcome such that even small amounts of LGE predicted a substantial increase in risk. The presence of septal LGE was associated with increased mortality, but SCD was most associated with the combined presence of septal and free-wall LGE. Predictive models using LGE presence and location were superior to models based on LGE extent or pattern. Conclusions In DCM, the presence of septal LGE is associated with a large increase in the risk of death and SCD events, even when the extent is small. SCD risk is greatest with concomitant septal and free-wall LGE. The incremental value of LGE extent beyond small amounts and LGE pattern is limited., Graphical abstract