Dilated Cardiomyopathy: Genetic Determinants and Mechanisms

Understanding inherited cardiomyopathies: clinical aspects and genetic determinants

Cardiomyopathies (CMs) are a clinically heterogeneous group of cardiovascular diseases characterized by structural and functional abnormalities of the heart muscle in the absence of coronary artery disease, hypertension, valve disease, or congenital heart disease as a leading cause. The phenotypic spectrum of CMs ranges from silent heart failure to symptomatic heart failure and sudden cardiac death, and CMs are one of the leading causes of cardiovascular morbidity worldwide. CMs are highly heritable, although a clear distinction between inherited and acquired forms remains challenging, particularly due to observed incomplete penetrance and variable expressivity of inherited CMs. Based on their specific morphological phenotypes and functional characteristics, CMs can be divided into at least 5 different subgroups: hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), arrhythmogenic cardiomyopathy (ACM), restrictive cardiomyopathy (RCM), and (left ventricular) non-compaction cardiomyopathy (LVNC), which show both clinical as well as genetic overlap. Since the identification of pathogenic variants in MYH7 as a genetic cause of HCM in 1990, enormous progress has been made in understanding genetic factors contributing to cardiomyopathies. Currently, over 100 genes have been associated with at least one of the CM subtypes, providing a deeper understanding of the cellular basis of genetic heart failure syndromes, unveiling new insights into the molecular biology of heart function in both health and disease, and, thereby, facilitating the development of novel therapeutic strategies and personalized treatment approaches.

Impact of Sorbs2 dysfunction on cardiovascular diseases

Despite significant advancements in prevention and treatment over the past decades, cardiovascular diseases (CVDs) remain the leading cause of death worldwide. CVDs involve multifactorial inheritance, but our understanding of the genetic impact on these diseases is still incomplete. Sorbin and SH3 domain-containing protein 2 (Sorbs2) is ubiquitously expressed in various tissues, including the cardiovascular system. Increasing evidence suggests that Sorbs2 malfunction contributes to CVDs. This manuscript will review our current understanding of the potential mechanisms underlying Sorbs2 dysregulation in the development of CVDs.

Hippo pathway activation mediates cardiomyocyte ferroptosis to promote dilated cardiomyopathy through downregulating NFS1

Cardiomyocyte loss by regulated death modes, like apoptosis and ferroptosis, has been implicated in the development of dilated cardiomyopathy (DCM). It remains unclear whether cardiomyocyte ferroptosis occurs as a consequence of Hippo pathway activation. Using a mouse model of DCM by overexpression of Mst1 transgene (Mst1-TG) leading to Hippo pathway activation, we showed that cardiomyocyte ferroptosis was evident by transcriptomic profiles, elevated mitochondrial Fe2+ content, increased levels of lipid peroxidation and obvious mitochondrial damage. Transcriptome revealed significant alterations of genes participating in iron metabolism and lipid peroxidation. Treatment of Mst1-TG mice with the ferroptosis inhibitor ferrostatin-1 reduced cardiomyocyte ferroptosis and improved cardiac function. Using heart samples from human patients with DCM, we also found significant cardiomyocyte loss and lipid peroxidation. In cultured cardiomyocytes, ferroptosis was induced by treatment with erastin or YAP inhibitor verteporfin, and cell ferroptosis under these conditions was largely prevented by either iron chelation or Mst1 gene knockdown. In a strain of transgenic mice with cardiomyocyte inactivation of Mst1 (dnMst1-TG), erastin-induced ferroptosis and cardiac dysfunction, seen in control mice, were mitigated. Mechanistically, nuclear YAP and YY1 were shown to interact and bind to the Nfs1 promoter, thus mediating downregulation of Nfs1 (encoding cysteine desulfurase). Subsequent inhibition of iron-sulfur cluster (ISC) biosynthesis promoted cardiomyocyte ferroptosis and DCM phenotype. Restoration of Nfs1 expression was achieved by treatment of Mst1-TG mice with AAV9-Nfs1 virus, which alleviated ferroptosis, mitochondrial damage and DCM phenotype. In conclusion, in the DCM model with Hippo pathway activation, our findings unravel that NFS1 downregulation occurs and leads to insufficient ISC biosynthesis and cardiomyocyte ferroptosis. Our findings implicate that restoration of cardiomyocyte NFS1 level may represent a new therapeutic strategy for DCM.

Decoding mitochondrial stress genes in DCM: towards precision diagnosis and therapy

BACKGROUND

Mitochondrial oxidative stress (ROS) is a crucial factor in the pathogenesis of dilated cardiomyopathy (DCM). Despite its significance, robust biomarkers for assessing its role remain scarce. This study investigates ROS mechanisms in DCM and identifies associated biomarkers, offering fresh insights into diagnosis and treatment.

METHODS

We sourced transcriptomic data from the GEO database and mitochondrial oxidative stress-related genes from GeneCards. Using consensus clustering, we identified 64 genes associated with mitochondrial oxidative stress in DCM and further isolated five hub genes through protein-protein interaction and machine learning techniques. These genes were analyzed for functions related to immunity, drug sensitivity, and single-cell localization. Concurrently, we collected blood samples from DCM patients to validate the hub genes' expression.

RESULTS

The study identified five hub genes related to mitochondrial oxidative stress: VCL, ABCB1, JAK2, KDR, and NGF. Expression analysis revealed high levels of VCL, ABCB1, KDR, and NGF in the non-failing (NF) group, while JAK2 was elevated in the DCM group (p < 0.05). Diagnostic efficacy, measured by area under the curve (AUC), was significant for VCL (76.4), ABCB1 (80.1), JAK2 (68.2), KDR (78.1), and NGF (71.8). Moreover, several drugs were identified as potential regulators of these hub genes, including Topotecan, CDK9_5576, Acetalax, Afatinib, and GSK591. Notably, VCL showed increased expression in DCM patient blood samples, consistent with transcriptomic and single-cell findings.

CONCLUSION

This research highlights key genes associated with mitochondrial oxidative stress-VCL, ABCB1, JAK2, KDR, NGF-that show differential expression in DCM and myocardial infarction. These findings underscore their diagnostic potential and pave the way for new therapeutic strategies.

Pitfalls in performing genome-wide association studies on ratio traits

Genome-wide association studies (GWASs) are often performed on ratios composed of a numerator trait divided by a denominator trait. Examples include body mass index (BMI) and the waist-to-hip ratio, among many others. Explicitly or implicitly, the goal of forming the ratio is typically to adjust for an association between the numerator and denominator. While forming ratios may be clinically expedient, there are several important issues with performing GWAS on ratios. Forming a ratio does not "adjust" for the denominator in the sense of conditioning on it, and it is unclear whether associations with ratios are attributable to the numerator, the denominator, or both. Here we demonstrate that associations arising in ratio GWAS can be entirely denominator driven, implying that at least some associations uncovered by ratio GWAS may be due solely to a putative adjustment variable. In a survey of 10 common ratio traits, we find that the ratio model disagrees with the adjusted model (performing GWAS on the numerator while conditioning on the denominator) at around 1/3 of loci. Using BMI as an example, we show that variants detected by only the ratio model are more strongly associated with the denominator (height), while variants detected by only the adjusted model are more strongly associated with the numerator (weight). Although the adjusted model provides effect sizes with a clearer interpretation, it is susceptible to collider bias. We propose and validate a simple method of correcting for the genetic component of collider bias via leave-one-chromosome-out polygenic scoring.

Long-Term Clinical Outcomes in Patients With Transthyretin Cardiac Amyloidosis Versus Non-Ischemic Cardiomyopathy

Background

We sought to compare the long-term outcomes in patients with transthyretin cardiac amyloidosis (CA) compared to those with non-ischemic cardiomyopathy (NICM) from a large healthcare system database.

Methods

Patients with CA or NICM were identified from SSM Healthcare System's data warehouse using ICD codes. Inclusion criteria included at least 6 months of follow-up. Outcomes studied were heart failure hospitalization (HFH), ventricular tachyarrhythmias (VTA), implantable cardiac defibrillator (ICD) and pacemaker (PM) placement. Multivariate logistic analysis and Kaplan-Meier survival curves were constructed.

Results

We identified 231 patients with CA and 462 with NICM, matched for age, race, and gender. CA patients had higher incidence of peripheral vascular disease (48.5% vs. 35.5%) and coronary artery disease (10.4% vs. 6.1%). Mean follow-up was 48.1 ± 33.1 months. CA patients had a higher rate of HFH (57.6% vs. 46.1%) and a lower rate of ICD (1.7% vs. 5.9%). In the multivariate model, CA patients had significantly higher odds for HFH (odds ratio: 1.86; 95% confidence interval: 1.29 - 2.68). Kaplan-Meier survival curves showed a trend toward earlier HFH and later PM or ICD implantation in CA patients.

Conclusions

In this retrospective study from a large healthcare system database, compared to NICM, transthyretin CA patients had significantly higher rates of HFH, similar odds of VTA, and a lower likelihood of receiving an intracardiac device.

Identification of dilated cardiomyopathy-linked key genes by bioinformatics methods and evaluating the impact of tannic acid and monosodium glutamate in rats

Dilated cardiomyopathy (DCM) is the most common type of myocardial dysfunction, affecting mostly young adults, but its therapeutic diagnosis and biomarkers for prognosis are lacking. This study aimed to investigate the possible effect of the common food additive monosodium glutamate (MSG) and tannic acid (TA), a phenolic compound, on the key molecular actors responsible for DCM. DCM-related publicly available microarray datasets (GSE120895, GSE17800, and GSE19303) were downloaded from the comprehensive Gene Expression Omnibus (GEO) database, and analyzed to identify differentially expressed genes (DEGs). By integrating DEGs and gene-disease validity curation results, overlapping genes were screened and identified as hub genes. Protein-protein interaction (PPI) network and ontology analysis were performed to make sense of the identified biological data. Finally, mRNA expression changes of identified hub genes in the heart tissues of rats treated with MSG and TA were measured by the qPCR method. Six upregulated (IGF1, TTN, ACTB, LMNA, EDN1, and NPPB) DEGs were identified between the DCM and healthy control samples as the hub genes. qPCR results revealed that the mRNA levels of these genes involved in DCM development increased significantly in rat heart tissues exposed to MSG. In contrast, this increase was remarkably alleviated by TA treatment. Our results provide new insights into critical molecular mechanisms that should be focused on in future DCM studies. Moreover, MSG may play a critical role in DCM formation, and TA may be used as a promising therapeutic agent in DCM.

Causes and consequences of DNA double-stranded breaks in cardiovascular disease

The genome, whose stability is essential for survival, is incessantly exposed to internal and external stressors, which introduce an estimated 104 to 105 lesions, such as oxidation, in the nuclear genome of each mammalian cell each day. A delicate homeostatic balance between the generation and repair of DNA lesions maintains genomic stability. To initiate transcription, DNA strands unwind to form a transcription bubble and provide a template for the RNA polymerase II (RNAPII) complex to synthesize nascent RNA. The process generates DNA supercoils and introduces torsional stress. To enable RNAPII processing, the supercoils are released by topoisomerases by introducing strand breaks, including double-stranded breaks (DSBs). Thus, DSBs are intrinsic genomic features of gene expression. The breaks are quickly repaired upon processing of the transcription. DNA lesions and damaged proteins involved in transcription could impede the integrity and efficiency of RNAPII processing. The impediment, which is referred to as transcription stress, not only could lead to the generation of aberrant RNA species but also the accumulation of DSBs. The latter is particularly the case when topoisomerase processing and/or the repair mechanisms are compromised. The DSBs activate the DNA damage response (DDR) pathways to repair the damaged DNA and/or impose cell cycle arrest and cell death. In addition, the release of DSBs into the cytosol activates the cytosolic DNA-sensing proteins (CDSPs), which along with the nuclear DDR pathways induce the expression of senescence-associated secretory phenotype (SASP), cell cycle arrest, senescence, cell death, inflammation, and aging. The primary stimulus in hereditary cardiomyopathies is a mutation(s) in genes encoding the protein constituents of cardiac myocytes; however, the phenotype is the consequence of intertwined complex interactions among numerous stressors and the causal mutation(s). Increased internal DNA stressors, such as oxidation, alkylation, and cross-linking, are expected to be common in pathological conditions, including in hereditary cardiomyopathies. In addition, dysregulation of gene expression also imposes transcriptional stress and collectively with other stressors provokes the generation of DSBs. In addition, the depletion of nicotinamide adenine dinucleotide (NAD), which occurs in pathological conditions, impairs the repair mechanism and further facilitates the accumulation of DSBs. Because DSBs activate the DDR pathways, they are expected to contribute to the pathogenesis of cardiomyopathies. Thus, interventions to reduce the generation of DSBs, enhance their repair, and block the deleterious DDR pathways would be expected to impart salubrious effects not only in pathological states, as in hereditary cardiomyopathies but also aging.

The effects of sodium-glucose cotransporter 2 inhibitors on the 'forgotten' right ventricle

With the progress in diagnosis, treatment and imaging techniques, there is a growing recognition that impaired right ventricular (RV) function profoundly affects the prognosis of patients with heart failure (HF), irrespective of their left ventricular ejection fraction (LVEF). In addition, right HF (RHF) is a common complication associated with various diseases, including congenital heart disease, myocardial infarction (MI), pulmonary arterial hypertension (PAH) and dilated cardiomyopathy (DCM), and it can manifest at any time after left ventricular assist devices (LVADs). The sodium-glucose cotransporter 2 (SGLT2) inhibition by gliflozins has emerged as a cornerstone medicine for managing type 2 diabetes mellitus (T2DM) and HF, with an increasing focus on its potential to enhance RV function. In this review, we aim to present an updated perspective on the pleiotropic effects of gliflozins on the right ventricle and offer insights into the underlying mechanisms. We can ascertain their advantageous impact on the right ventricle by discussing the evidence obtained in animal models and monumental clinical trials. In light of the pathophysiological changes in RHF, we attempt to elucidate crucial mechanisms regarding their beneficial effects, including alleviation of RV overload, reduction of hyperinsulinaemia and inflammatory responses, regulation of nutrient signalling pathways and cellular energy metabolism, inhibition of oxidative stress and myocardial fibrosis, and maintenance of ion balance. Finally, this drug class's potential application and benefits in various clinical settings are described, along with a prospective outlook on future clinical practice and research directions.

Dilated cardiomyopathy: from genes and molecules to potential treatments

Dilated cardiomyopathy is a myocardial condition marked by the enlargement of the heart's ventricular chambers and the gradual decline in systolic function, frequently resulting in congestive heart failure. Dilated cardiomyopathy has obvious familial characteristics, and mutations in related pathogenic genes can account for about 50% of patients with dilated cardiomyopathy. The most common genes related to dilated cardiomyopathy include TTN, LMNA, MYH7, etc. With more and more research on these genes, it will undoubtedly provide more potential targets and therapeutic pathways for the treatment of dilated cardiomyopathy. In addition, myocardial inflammation, myocardial metabolism abnormalities and cardiomyocyte apoptosis all have an important impact on the pathogenesis of dilated cardiomyopathy. Approximately half of sudden deaths among children and adolescents, along with the majority of patients undergoing heart transplantation, stem from cardiomyopathy. Therefore, precise and prompt clinical diagnosis holds paramount importance. Currently, diagnosis primarily hinges on the patient's medical background and imaging tests, with the significance of genetic testing steadily gaining prominence. The primary treatment for dilated cardiomyopathy remains heart transplantation. However, the scarcity of donors and the risk of severe immune rejection underscore the pressing need for novel therapies. Presently, research is actively exploring preclinical treatments like stem cell therapy as potential solutions.

Dilated Cardiomyopathy: A Novel BAG3 Mutation Associated with Aggressive Disease Progression and Ventricular Arrhythmias

We present the case of a 46-year-old man with a history of complex ventricular arrhythmias preceding the development of asymptomatic mild left ventricular dysfunction, who presented with acute-onset heart failure and was ultimately diagnosed with dilated cardiomyopathy. Genetic testing identified a novel, likely pathogenic mutation in exon 4 of the BAG3 gene (NM_004281, c.1128del, (p.(Ser377AlafsTer47)), not previously reported in the literature. Given the presence of multiple clinical features indicative of a poor prognosis, he underwent prophylactic placement of a subcutaneous implantable cardioverter-defibrillator. The clinical presentation of this novel BAG3 mutation suggests that it may be associated with a significant arrhythmic phenotype. This case underscores the importance of close follow-up and genetic testing in patients presenting with mild left ventricular dysfunction and ventricular arrhythmias.

Mammalian TatD DNase domain containing 1 (TATDN1) is a proteostasis-responsive gene with roles in ventricular structure and neuromuscular function

The characterization of highly conserved but poorly understood genes often reveals unexpected biological roles, advancing our understanding of disease mechanisms. One such gene is Mammalian TatD DNase domain containing 1 (Tatdn1), the mammalian homolog of bacterial Twin-arginine translocation D (TatD), a protein proposed to have roles either in DNA degradation or protein quality control in unicellular organisms. Despite its association with different pathologies, including several cancer types and cardiovascular diseases, the role of TATDN1 in mammals remains unexplored. Here, we demonstrate that Tatdn1 encodes a cytoplasmic protein that does not participate in DNA degradation but is upregulated in cells under proteostasis stress. Tatdn1-deficient mice exhibit dysregulated expression of genes involved in membrane and extracellular protein biology, along with mild dilated cardiomyopathy and impaired motor coordination. These findings identify TATDN1 as a key player in cytosolic processes linked to protein homeostasis, with significant physiological implications for cardiac and neurological function.

Association of the TTN, PDK4, and RNF207 mutations with dilated cardiomyopathy in Dobermanns from the United Kingdom

A missense mutation in the titin gene (TTN) and a splice-site mutation in the pyruvate dehydrogenase kinase 4 gene (PDK4) have been associated with dilated cardiomyopathy (DCM) in Dobermanns from the United States. Additionally, a missense mutation in the gene RNF207 has been reported in association with DCM from a European Dobermann cohort. Based on this we examined the association of these variants with DCM in United Kingdom (UK) Dobermanns. We hypothesized that the TTN and PDK4 gene variants would not be associated with DCM in UK Dobermanns and that there would be an association between the RNF207 mutation and DCM. We included 74 client owned dogs (30 control dogs and 44 dogs with DCM) in the study. Allele frequencies for each variant were calculated. Chi-square testing was used to assess for differences in allele frequencies and genotype proportions between groups. Overall allele frequency in this cohort was 35% for the TTN variant, 18% for the PDK4 variant, and 37% for the RNF207 variant. There was no difference in allele or genotype frequencies between control and DCM dogs for TTN or PDK4 (p =  0.79 for both allele frequencies, p =  0.91 for TTN and p =  0.78 for PDK4 genotype frequencies). There was a significant difference in the allele frequencies of the RNF207 variant between DCM cases and controls (OR 2.4 (95% CI 1.07 - 5.15), p =  0.03) and genotype frequencies for RNF207, with a homozygous genotype found almost exclusively in DCM dogs (p =  0.034). We conclude that the previously reported RNF207 variant appears associated with DCM in UK Dobermanns, but there was no association with the previously reported TTN or PDK4 mutations. This is important when considering selective breeding in different populations of Dobermanns. However, the small sample size may impact the generalizability of the results.

Clinical and Echocardiographic Risk Factors of Adverse Outcomes in Young Patients With Dilated Cardiomyopathy

Purpose: This study is aimed at identifying clinical and echocardiographic factors associated with all-cause mortality or heart transplantation (HTx) in young patients with dilated cardiomyopathy (DCM). Methods: We conducted a retrospective analysis of hospitalized patients (aged 18-45 years) diagnosed with DCM between January 2012 and December 2022. All patients underwent a 2-year medical therapy for heart failure, followed by at least 1 year of follow-up. Clinical and echocardiographic data were collected at baseline and after the 2-year treatment period. Multivariate Cox proportional hazards regression with a backward stepwise method was used to identify risk factors for all-cause mortality or HTx. Results: The study cohort comprised 67 patients. Over a median follow-up of 38 months (range 18-50), 15 patients died and 24 underwent HTx. Significant risk factors for all-cause mortality/HTx included smoking, digoxin use, elevated N-terminal pro-brain natriuretic peptide (NT-proBNP, ≥ 5678 pg/mL), higher C-reactive protein (CRP, ≥ 3.0 mg/L), higher uric acid (UA, ≥ 570 μmol/L), lower left ventricular ejection fraction (LVEF, ≤25%), and enlarged end-diastolic left ventricular diameter (LVD, ≥ 65 mm). Among these, elevated CRP (hazard ratio, HR = 6.727, p < 0.001) and enlarged LVD (HR = 3.038, p = 0.007) were the strongest independent risk factors, irrespective of other risk factors. Moreover, each 5 mm annual increase in end-systolic left atrial diameter (LAD, HR = 3.641, p < 0.001) and each unit annual increase in Ln(NT-proBNP) (HR = 4.069, p < 0.001) were the strongest predictors of all-cause mortality/HTx, even after accounting for the effects of body mass index, duration of treatment, and baseline CRP level. Conclusions: Intensive monitoring and medical care may be beneficial for young adult DCM patients with defined risk factors such as smoking, elevated NT-proBNP and CRP, lower LVEF, and enlarged LV diameter. Our findings suggest that personalized intensive monitoring and medical care based on identified risk factors may improve outcomes in young adult DCM patients.

KLHL24 associated cardiomyopathy: Gene function to clinical management

BACKGROUND

KLHL24 (Kelch-like protein 24) is a significant component of the ubiquitin-proteasome system (UPS), involved in regulating protein turnover through targeted ubiquitination and degradation. Germline mutations in KLHL24 gene have been known to cause Epidermolysis Bullosa Simplex characterized by skin fragility but has recently been found to cause Cardiomyopathy.

MAIN BODY

Various cardiomyopathies, including hypertrophic cardiomyopathy and dilated cardiomyopathy, leading to abnormal protein degradation and affecting the stability and function of essential cardiac proteins which finally results into structural and functional abnormalities in cardiac muscle. In this review, in order to understand the disease association of germline mutations of KLHL24, we summarize all the studies performed with KLHL24 gene including studies from 2016 when KLHL24 was first identified to be associated with epidermolysis bullosa simplex till the recent studies in 2024 by using keywords such as KLHL24 gene, hypertrophic cardiomyopathy, dilated cardiomyopathy and epidermolysis bullosa simplex. Furthermore, we explored the proposed molecular mechanisms and pathophysiologies of KLHL24 associated diseases. Patients with KLHL24 mutations were usually presented with variable clinical symptoms. The main clinical presentations have been cutaneous lesions, cardiac symptoms associated with cardiomyopathies and there have been reports of skeletal muscle weakness and neurological symptoms as well. Current treatments focus on managing clinical symptoms and preventing complications through medications, lifestyle changes, and surgical interventions. In addition, researches have also been conducted cell culture based in vitro studies for reducing the clinical symptoms of KLHL24 associated diseases. However, currently there are no specific clinical trials going on regarding the therapeutic strategies among patients with KLHL24 mutations. Understanding the role of KLHL24 in cardiomyopathies is very important for developing targeted diagnostic approach with therapeutic strategies.

CONCLUSION

This review emphasizes the importance of KLHL24 mutations as a newly recognized cause of cardiomyopathy, paving the way for improved clinical diagnosis, targeted therapies, and ultimately, for better patient outcomes.

Patterns of Cardiomyopathy in Patients Presenting to a Tertiary Care Hospital

BACKGROUND

Cardiomyopathy is a broad category of myocardial conditions that have a substantial effect on heart function. Improving patient treatment requires a knowledge of its epidemiology.

OBJECTIVE

The aim of this study was to determine the pattern of cardiomyopathy in patients presenting to a tertiary care hospital in Peshawar, Pakistan.

METHODOLOGY

This cross-sectional study was conducted at the Department of Cardiology, Northwest General Hospital & Research Centre, Peshawar, from December 14, 2022, to June 14, 2023. There were 79 individuals with cardiomyopathy who were 16 years of age or older. Clinical and demographic information, such as age, gender, BMI, length of illness, and family history, were gathered. Cardiomyopathy patterns were classified using echocardiographic evaluations, and IBM SPSS Statistics for Windows, version 25 (IBM Corp., Armonk, NY) was employed for statistical analysis.

RESULTS

The average age of the 79 participants was 45.72 ± 2.45 years, and 40.5% (n=32) were between the ages of 51 and 60. There were 63.3% male individuals (n=50) and 36.7% female individuals (n=29). With 69.6% (n=55) and 30.4% (n=24) having a duration of symptoms ≤1 month and >1 month, respectively. 38.0% (n=30) had a family history of cardiomyopathy. With dilated, hypertrophic, and peripartum cardiomyopathy each at 15.2%, the most prevalent forms of cardiomyopathy were restrictive (20.3%, n=16), ischemic (17.7%, n=14), and arrhythmogenic right ventricular (16.5%, n=13). BMI (p = 0.000) and illness duration (p = 0.000) were substantially correlated with dilated and hypertrophic cardiomyopathies. Older age groups, especially those between the ages of 51 and 60, had a greater prevalence of cardiomyopathy (p = 0.000). Dilated cardiomyopathy (p = 0.000) and peripartum cardiomyopathy (p = 0.000) were significantly influenced by family history.

CONCLUSION

The research highlights the variety of cardiomyopathy patterns seen in a tertiary care facility, with ischemic and restrictive forms being the most prevalent. This highlights the need for specialized diagnosis and treatment strategies.

Sequencing in over 50,000 cases identifies coding and structural variation underlying atrial fibrillation risk

Atrial fibrillation (AF) is a prevalent and morbid abnormality of the heart rhythm with a strong genetic component. Here, we meta-analyzed genome and exome sequencing data from 36 studies that included 52,416 AF cases and 277,762 controls. In burden tests of rare coding variation, we identified novel associations between AF and the genes MYBPC3, LMNA, PKP2, FAM189A2 and KDM5B. We further identified associations between AF and rare structural variants owing to deletions in CTNNA3 and duplications of GATA4. We broadly replicated our findings in independent samples from MyCode, deCODE and UK Biobank. Finally, we found that CRISPR knockout of KDM5B in stem-cell-derived atrial cardiomyocytes led to a shortening of the action potential duration and widespread transcriptomic dysregulation of genes relevant to atrial homeostasis and conduction. Our results highlight the contribution of rare coding and structural variants to AF, including genetic links between AF and cardiomyopathies, and expand our understanding of the rare variant architecture for this common arrhythmia.

Pathophysiology of dilated cardiomyopathy: from mechanisms to precision medicine

Dilated cardiomyopathy (DCM) is a complex disease with multiple causes and various pathogenic mechanisms. Despite improvements in the prognosis of patients with DCM in the past decade, this condition remains a leading cause of heart failure and premature death. Conventional treatment for DCM is based on the foundational therapies for heart failure with reduced ejection fraction. However, increasingly, attention is being directed towards individualized treatments and precision medicine. The ability to confirm genetic causality is gradually being complemented by an increased understanding of genotype-phenotype correlations. Non-genetic factors also influence the onset of DCM, and growing evidence links genetic background with concomitant non-genetic triggers or precipitating factors, increasing the extreme complexity of the pathophysiology of DCM. This Review covers the spectrum of pathophysiological mechanisms in DCM, from monogenic causes to the coexistence of genetic abnormalities and triggering environmental factors (the 'two-hit' hypothesis). The roles of common genetic variants in the general population and of gene modifiers in disease onset and progression are also discussed. Finally, areas for future research are highlighted, particularly novel therapies, such as small molecules, RNA and gene therapy, and measures for the prevention of arrhythmic death.

The role of genetics in the prognosis of acute myocarditis: a systematic review and meta-analysis

Myocarditis is a heterogeneous disease with varying clinical presentations, etiologies, and courses. Apart from environmental factors, genetic factors may also play a role in its pathophysiology. Through a systematic review and meta-analysis, we aimed to characterize the relationship between acute myocarditis (AM), underlying genetic background, and prognosis. We searched on MEDLINE/PubMed and Web of Science for studies reporting clinical outcomes of patients presenting with AM and undergoing genetic testing. The prevalence of a positive genetic test result was 27.3%, with a higher proportion of males (61.3%). Patients with a positive genetic test often had a family history of cardiovascular events (53.3%) and late gadolinium enhancement on cardiac magnetic resonance (81.2%), suggesting that these clinical features may represent a population with a higher burden of genetic background and risk for worse outcomes. The risk of recurrence of AM among patients with a positive genetic test was four times greater than among non-carriers (RR=4.02, p<0.001), and the most frequently observed variants among AM carriers were in the TTN, DSP, PKP2, MYH7, BAG3, RMB20, DSG2, TNNT2, and SCN5A genes. Overall, these findings underscore the need to improve the criteria used for genetic testing in the setting of AM episodes and to identify affected individuals who may benefit from increased surveillance and genetic testing.

2025 Heart Disease and Stroke Statistics: A Report of US and Global Data From the American Heart Association

BACKGROUND

The American Heart Association (AHA), in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, nutrition, sleep, and obesity) and health factors (cholesterol, blood pressure, glucose control, and metabolic syndrome) that contribute to cardiovascular health. The AHA Heart Disease and Stroke Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, brain health, complications of pregnancy, kidney disease, congenital heart disease, rhythm disorders, sudden cardiac arrest, subclinical atherosclerosis, coronary heart disease, cardiomyopathy, heart failure, valvular disease, venous thromboembolism, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The AHA, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States and globally to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2025 AHA Statistical Update is the product of a full year's worth of effort in 2024 by dedicated volunteer clinicians and scientists, committed government professionals, and AHA staff members. This year's edition includes a continued focus on health equity across several key domains and enhanced global data that reflect improved methods and incorporation of ≈3000 new data sources since last year's Statistical Update.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Regulation of TTN as a mechanism of and treatment for heart failure

Truncation variants in the gene TTN encoding titin are the most common cause of familial dilated cardiomyopathy (DCM), with both haploinsufficiency and "poison peptide" implicated as contributory mechanisms of disease. In this issue of the JCI, Kim et al. identify a highly conserved enhancer element approximately 500 bp downstream of the transcriptional start site of TTN in intron 1, which they demonstrated to be critical in regulating TTN expression. This work helps to further clarify the relative role of haploinsufficiency in TTN-related DCM and provides a potential target for therapies aimed at treating TTN-related DCM.

An FDA-approved drug structurally and phenotypically corrects the K210del mutation in genetic cardiomyopathy models

Dilated cardiomyopathy (DCM) due to genetic disorders results in decreased myocardial contractility, leading to high morbidity and mortality rates. There are several therapeutic challenges in treating DCM, including poor understanding of the underlying mechanism of impaired myocardial contractility and the difficulty of developing targeted therapies to reverse mutation-specific pathologies. In this report, we focused on K210del, a DCM-causing mutation, due to 3-nucleotide deletion of sarcomeric troponin T (TnnT), resulting in loss of Lysine210. We resolved the crystal structure of the troponin complex carrying the K210del mutation. K210del induced an allosteric shift in the troponin complex resulting in distortion of activation Ca2+-binding domain of troponin C (TnnC) at S69, resulting in calcium discoordination. Next, we adopted a structure-based drug repurposing approach to identify bisphosphonate risedronate as a potential structural corrector for the mutant troponin complex. Cocrystallization of risedronate with the mutant troponin complex restored the normal configuration of S69 and calcium coordination. Risedronate normalized force generation in K210del patient-induced pluripotent stem cell-derived (iPSC-derived) cardiomyocytes and improved calcium sensitivity in skinned papillary muscles isolated from K210del mice. Systemic administration of risedronate to K210del mice normalized left ventricular ejection fraction. Collectively, these results identify the structural basis for decreased calcium sensitivity in K210del and highlight structural and phenotypic correction as a potential therapeutic strategy in genetic cardiomyopathies.

Region and cell-type resolved multi-omic altas of the heart

The heart is a vital muscular organ in vertebrate animals, responsible for maintaining blood circulation through rhythmic contraction. Although previous studies have investigated the heart proteome, the full hierarchical molecular network at cell-type and region resolved level, illustrating the specialized roles and crosstalk among different cell types and regions, remains unclear. Here, we presented an atlas of cell-type resolved proteome for mouse heart and region resolved proteome for both mouse and human hearts. In-depth proteomic analysis identified 11,794 proteins across four cell types and 11,995 proteins across six regions of the mouse heart. To further illustrate protein expression patterns in both physiological and pathological conditions, we conducted proteomic analysis on human heart samples from four regions with dilated cardiomyopathy (DCM). We quantified 8,201 proteins in DCM tissue and 8,316 proteins in adjacent unaffected myocardium (AUM) tissue across the four human heart regions. Notably, we found that the retinoic acid synthesis pathway was significantly enriched in the DCM-affected left ventricle, and functional experiments demonstrated that all-trans retinoic acid (atRA) efficiently rescued Ang II-induced myocardial hypertrophy and transverse aorta constriction (TAC)- induced heart failure. In conclusion, our datasets uncovered the functional features of different cell types and their synergistic cooperation centered by cell-type specific transcription factors (ctsTF) in different regions, while these TF-TG (target gene) axes were significantly altered in DCM. Additionally, atRA was demonstrated to be an efficient treatment for heart failure. This work presented a panoramic heart proteome map, offering a valuable resource for future cardiovascular research.

The 'Padua classification' of cardiomyopathies into three groups: hypertrophic/restrictive, dilated/hypokinetic, and scarring/arrhythmogenic

The newly proposed classification of cardiomyopathies, referred to as 'the Padua Classification', is based on both pathobiological basis (genetics, molecular biology, and pathology) and clinical features (morpho-functional and structural ventricular remodelling as evidenced by cardiac magnetic resonance). Cardiomyopathies are grouped into tree main categories and characterized by a designation combining both 'anatomical' and 'functional' features: hypertrophic/restrictive, dilated/hypokinetic, and scarring/arrhythmogenic; each cardiomyopathy group includes either genetic or non-genetic aetiologic variants. This novel approach aims to enhance the diagnostic accuracy and to support 'disease-specific' therapeutic strategies, with the objective to improve patient management and outcome.

Dilated cardiomyopathy variant R14del increases phospholamban pentamer stability, blunting dynamic regulation of calcium

The sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA) is a membrane transporter that creates and maintains intracellular Ca2+ stores. In the heart, SERCA is regulated by an inhibitory interaction with the monomeric form of the transmembrane micropeptide phospholamban (PLB). PLB also forms avid homo-pentamers, and the dynamic exchange of PLB between pentamers and SERCA is an important determinant of cardiac responsiveness to exercise. Here, we investigated two naturally occurring pathogenic variants of PLB: a cysteine substitution of Arg9 (R9C) and an in-frame deletion of Arg14 (R14del). Both variants are associated with dilated cardiomyopathy. We previously showed that the R9C mutation causes disulfide crosslinking and hyperstabilization of pentamers. While the pathogenic mechanism of R14del is unclear, we hypothesized this mutation may also alter pentamer stability. Immunoblots revealed a significantly increased pentamer: monomer ratio for R14del-PLB compared to WT-PLB. We quantified homo-oligomerization and SERCA-binding in live cells using fluorescence resonance energy transfer (FRET) microscopy. R14del-PLB showed an increased affinity for homo-oligomerization and decreased binding affinity for SERCA compared to WT. The data suggest that, like R9C, the R14del mutation stabilizes PLB in pentamers, decreasing its ability to regulate SERCA. The R14del mutation reduced the rate of PLB unbinding from pentamers after transient elevations of Ca2+, limiting the recovery of PLB-SERCA complexes. A computational model predicted that hyperstabilization of PLB pentamers by R14del impairs the ability of cardiac Ca2+ handling to respond to changing heart rates between rest and exercise. We postulate that impaired responsiveness to physiological stress contributes to arrhythmogenesis in human carriers of the R14del mutation.

The Future of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9 Gene Therapy in Cardiomyopathies: A Review of Its Therapeutic Potential and Emerging Applications

Cardiomyopathies, among the leading causes of heart failure and sudden cardiac death, are often driven by genetic mutations affecting the heart's structural proteins. Despite significant advancements in understanding the genetic basis of hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC), effective long-term therapies remain limited. The advent of clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (Cas9) gene editing offers a promising therapeutic strategy to address these genetic disorders at their root. CRISPR-Cas9 enables precise modification of pathogenic variants (PVs) in genes encoding sarcomeric and desmosomal proteins, which are frequently implicated in cardiomyopathies. By inducing site-specific double-stranded breaks in DNA, followed by repair through nonhomologous end joining (NHEJ) or homology-directed repair (HDR), this system allows for targeted correction of mutations. In preclinical models, CRISPR-Cas9 has shown promise in correcting HCM-associated mutations in β-myosin heavy chain 7 (MYH7), preventing disease phenotypes such as ventricular hypertrophy and myocardial fibrosis. Similarly, gene editing has successfully rectified DCM-linked mutations in Titin (TTN) and LMNA, resulting in improved heart function and reduced pathological remodeling. For ARVC, CRISPR-Cas9 has demonstrated the ability to repair mutations in desmosomal genes such as plakophilin 2 (PKP2), thereby restoring normal cardiac function and cellular adhesion. Despite these successes, challenges remain, including mosaicism, delivery efficiency, and off-target effects. Nevertheless, CRISPR-Cas9 represents a transformative approach to treating genetic cardiomyopathies, potentially offering long-lasting cures by directly addressing their underlying genetic causes.

Genotype-phenotype insights of pediatric dilated cardiomyopathy

Dilated cardiomyopathy (DCM) in children is a severe myocardial disease characterized by enlargement of the left ventricle or both ventricles with impaired contractile function. DCM can cause adverse consequences such as heart failure, sudden death, thromboembolism, and arrhythmias. This article reviews the latest advances in genotype and phenotype research in pediatric DCM. With the development of gene sequencing technologies, considerable progress has been made in genetic research on DCM. Research has shown that DCM exhibits notable genetic heterogeneity, with over 100 DCM-related genes identified to date, primarily involving functions such as calcium handling, the cytoskeleton, and ion channels. As human genomic variations are linked to phenotypes, DCM phenotypes are influenced by numerous genetic variations across the entire genome. Children with DCM display high genetic heterogeneity and are characterized by early onset, rapid disease progression, and poor prognosis. The genetic architecture of pediatric DCM markedly differs from that of adult DCM, necessitating analyses through clinical phenotyping, familial cosegregation studies, and functional validation. Clarifying the genotype-phenotype relationship can improve diagnostic accuracy, enhance prognosis, and guide follow-up treatment for genotype-positive and phenotype-negative patients identified through genetic testing, providing new insights for precision medicine. Future research should further explore novel pathogenic genes and mutations and strengthen genotype-phenotype correlation analyses to facilitate precise diagnosis and treatment of DCM in children.

Pathogenetic mechanisms of muscle-specific ribosomes in dilated cardiomyopathy

The heart employs a specialized ribosome in its muscle cells to translate genetic information into proteins, a fundamental adaptation with an elusive physiological role1-3. Its significance is underscored by the discovery of neonatal patients suffering from often fatal heart failure caused by severe dilated cardiomyopathy when both copies of the gene RPL3L are mutated4-9. RPL3L is a muscle-specific paralog1-3 of the ubiquitous ribosomal protein L3 (RPL3), which makes the closest contact of any protein to the ribosome's RNA-based catalytic center10. RPL3L-linked heart failure represents the only known human disease associated with tissue-specific ribosomes, yet the underlying pathogenetic mechanisms remain poorly understood. Intriguingly, disease is linked to a large number of mostly missense variants in RPL3L, and RPL3L-knockout resulted in no severe heart defect in either human or mice3, 11-13, challenging the prevailing view that autosomal recessive diseases are caused by loss-of-function mutations. Here, we report three new cases of RPL3L-linked severe neonatal heart failure and present a unifying pathogenetic mechanism by which a large number of variants in the muscle-specific ribosome led to disease. Specifically, affected families often carry one of two recurrent toxic gain-of-function variants alongside a family-specific putative loss-of-function variant. While the non-recurrent variants often trigger partial compensation of RPL3 similar to Rpl3l-knockout mice, both recurrent variants exhibit increased affinity for the RPL3/RPL3L chaperone GRWD114-16 and 60S biogenesis factors, sequester 28S rRNA in the nucleus, disrupt ribosome biogenesis, and trigger severe cellular toxicity that extends beyond the loss of ribosomes. These findings provide critical insights for genetic screening and therapeutic development of neonatal heart failure. Our results suggest that gain-of-toxicity mechanisms may be more prevalent in autosomal recessive diseases, and a combination of gain-of-toxicity and loss-of-function mechanisms could underlie many diseases involving genes with paralogs.

Mechanisms underlying dilated cardiomyopathy associated with FKBP12 deficiency

Dilated cardiomyopathy (DCM) is a highly prevalent and genetically heterogeneous condition that results in decreased contractility and impaired cardiac function. The FK506-binding protein FKBP12 has been implicated in regulating the ryanodine receptor in skeletal muscle, but its role in cardiac muscle remains unclear. To define the effect of FKBP12 in cardiac function, we generated conditional mouse models of FKBP12 deficiency. We used Cre recombinase driven by either the α-myosin heavy chain, (αMHC) or muscle creatine kinase (MCK) promoter, which are expressed at embryonic day 9 (E9) and E13, respectively. Both conditional models showed an almost total loss of FKBP12 in adult hearts compared with control animals. However, only the early embryonic deletion of FKBP12 (αMHC-Cre) resulted in an early-onset and progressive DCM, increased cardiac oxidative stress, altered expression of proteins associated with cardiac remodeling and disease, and sarcoplasmic reticulum Ca2+ leak. Our findings indicate that FKBP12 deficiency during early development results in cardiac remodeling and altered expression of DCM-associated proteins that lead to progressive DCM in adult hearts, thus suggesting a major role for FKBP12 in embryonic cardiac muscle.

The transcriptional repressor HEY2 regulates mitochondrial oxidative respiration to maintain cardiac homeostasis

Energy deprivation and metabolic rewiring of cardiomyocytes are widely recognized hallmarks of heart failure. Here, we report that HEY2 (a Hairy/Enhancer-of-split-related transcriptional repressor) is upregulated in hearts of patients with dilated cardiomyopathy. Induced Hey2 expression in zebrafish hearts or mammalian cardiomyocytes impairs mitochondrial respiration, accompanied by elevated ROS, resulting in cardiomyocyte apoptosis and heart failure. Conversely, Hey2 depletion in adult mouse hearts and zebrafish enhances the expression of mitochondrial oxidation genes and cardiac function. Multifaceted genome-wide analyses reveal that HEY2 enriches at the promoters of genes known to regulate metabolism (including Ppargc1, Esrra and Cpt1) and colocalizes with HDAC1 to effectuate histone deacetylation and transcriptional repression. Consequently, restoration of PPARGC1A/ESRRA in Hey2- overexpressing zebrafish hearts or human cardiomyocyte-like cells rescues deficits in mitochondrial bioenergetics. Knockdown of Hey2 in adult mouse hearts protects against doxorubicin-induced cardiac dysfunction. These studies reveal an evolutionarily conserved HEY2/HDAC1-Ppargc1/Cpt transcriptional module that controls energy metabolism to preserve cardiac function.

The "Padua classification" of cardiomyopathies: Combining pathobiological basis and morpho-functional remodeling

Over the last 20 years, the scientific progresses in molecular biology and genetics in combination with the increasing use in the clinical setting of contrast-enhanced cardiac magnetic resonance (CMR) for morpho-functional imaging and structural myocardial tissue characterization have provided important new insights into our understanding of the distinctive aspects of cardiomyopathy, regarding both the genetic and biologic background and the clinical phenotypic features. This has led to the need of an appropriate revision and upgrading of current nosographic framework and pathobiological categorization of heart muscle disorders. This article proposes a new definition and classification of cardiomyopathies that rely on the combination of the distinctive pathobiological basis (genetics, molecular biology and pathology) and the clinical phenotypic pattern (morpho-functional and structural features), leading to the proposal of three different disease categories, each of either genetic or non-genetic etiology and characterized by a combined designation based on both "anatomic" and "functional" features, i.e., hypertrophic/restrictive (H/RC), dilated/hypokinetic (D/HC) and scarring/arrhythmogenic cardiomyopathy (S/AC). The clinical application of the newly proposed classification approach in the real-world practice appears crucial to design a targeted clinical management and evaluation of outcomes of affected patients. Although current treatment of cardiomyopathies is largely palliative and based on drugs, catheter ablation, device or surgical interventions aimed to prevent and manage heart failure and malignant arrhythmias, better knowledge of basic mechanisms involved in the onset and progression of pathobiologically different heart muscle diseases may allow to the development of disease-specific curative therapy.

Mendelian Randomization Study on the Associations Between Genetically Predicted Cardiovascular Disease Subtypes and the Risk of Developing Cardiomyopathies

Cardiomyopathies are commonly believed to have genetic origins; however, the connection between cardiomyopathies and cardiovascular diseases remains uncertain. Thus, we employed a Mendelian randomization (MR) approach to investigate the potential causal effects of specific cardiovascular disease subtypes on dilated and hypertrophic cardiomyopathies, focusing primarily on a European population. Summary-level data for cardiomyopathies and other cardiovascular diseases were obtained from public genome-wide association studies. Random-effects inverse-variance weighting was used as the primary analysis, whereas sensitivity analyses, including weighted median, MR-Egger, and multivariable MR methods, were also conducted. A genetic predisposition to atrial fibrillation [odds ratio (OR): 1.33; 95% confidence interval (CI): 1.18-1.50; P < 0.001], heart failure (OR: 3.22; 95% CI: 1.92-5.41; P < 0.001), and hypertension (OR: 1.50; 95% CI: 1.25-1.81; P < 0.001) were causally linked to an increased risk of developing dilated cardiomyopathy. However, there was no direct causal connection between genetically predicted coronary heart disease, pulmonary embolism, or ischemic stroke and the risk of developing dilated cardiomyopathy. In contrast, no significant associations were found between genetically predicted CVD subtypes and the risk of developing hypertrophic cardiomyopathy. Genetically predicted heart failure is significantly associated with the risk of developing dilated cardiomyopathy, underscoring the importance of effective heart failure management for risk prevention. Moreover, individuals with hypertension and atrial fibrillation might have an increased predisposition to dilated cardiomyopathy, highlighting crucial implications for management.

Differential Expression Spectrum of circRNA in Plasma Exosomes in Dilated Cardiomyopathy With Heart Failure

Dilated cardiomyopathy (DCM), a form of non-ischaemic myocardial disease, is characterised by structural and functional cardiac abnormalities. As defined by the World Health Organisation, DCM constitutes a significant cardiac pathology, leading to increased morbidity and mortality due to complications such as heart failure and arrhythmias. The diagnostic process for DCM predominantly employs echocardiography and MRI, with biomarkers like NT-pro BNP and troponin providing supportive, yet non-specific, evidence. Exosomes, small extracellular vesicles, play a critical role in intercellular communications by transferring biomolecules including lipids, proteins, messenger RNA (mRNA) and non-coding RNA (ncRNA) to target cells, thereby influencing key cellular processes such as proliferation, differentiation, apoptosis, angiogenesis and immune modulation. Within the ncRNA category, circular RNAs (circRNAs) are notable for their cellular specificity and evolutionary conservation and are often implicated in the regulatory mechanisms underlying DCM and heart failure. This investigation employed next-generation sequencing technology to analyse plasma exosomal circRNA profiles in DCM patients with chronic heart failure (CHF), compared to healthy controls. The analysis revealed distinct circRNA expression patterns, identifying 49 uniquely expressed circRNAs in the DCM cohort with CHF. These circRNAs were associated with several critical biological pathways, including the sequestration of extracellular ligands from receptors, N-acetyltransferase activity, histone acetyltransferase activity and endocytic vesicle membrane composition. The findings of this study provide valuable insights into the pathophysiological mechanisms of DCM and offer evidence for improving clinical diagnostic methodologies.

Generation of a human induced pluripotent stem cell line from a female patient carrying LZTR1 gene mutation

The leucine zipper-like transcriptional regulator 1 (LZTR1) gene has been reported to be associated with many kinds of human diseases, including cardiac disease, Noonan syndrome, and schwannomatosis. In this study, peripheral blood mononuclear cells (PBMCs) derived from patient diagnosed with dilated cardiomyopathy (DCM) was successfully reprogrammed into the human induced pluripotent stem cells (iPSCs) line, harboring a distinct heterozygous mutation in the LZTR1 gene. The established patient-derived iPSCs expressed endogenous pluripotent markers, demonstrated the potential to differentiate into three germ layers (endoderm, mesoderm, and ectoderm), and exhibited a normal karyotype.

Unraveling the nexus of nesprin in dilated cardiomyopathy: From molecular insights to therapeutic prospects

Dilated cardiomyopathy is a complex and debilitating heart disorder characterized by the enlargement and weakening of the cardiac chambers, leading to impaired contractility and heart failure. Nesprins, a family of nuclear envelope spectrin repeat proteins that include isoforms Nesprin-1/-2, are integral components of the LInker of Nucleoskeleton and Cytoskeleton complex. They facilitate the connection between the nuclear envelope and the cytoskeleton, crucial for maintaining nuclear architecture, migration and positioning, and mechanical transduction and signaling. Nesprin-1/-2 are abundantly expressed in cardiac and skeletal muscles.They have emerged as key players in the pathogenesis of dilated cardiomyopathy. Mutations in synaptic nuclear envelope-1/-2 genes encoding Nesprin-1/-2 are associated with dilated cardiomyopathy, underscoring their significance in cardiac health. This review highlights the all known cases of Nesprin-1/-2 related dilated cardiomyopathy, focusing on their interactions with the nuclear envelope, their role in mechanical transduction, and their influence on gene expression. Moreover, it delves into the underlying mechanisms through which Nesprin dysfunction disrupts nuclear-cytoskeletal coupling, leading to abnormal nuclear morphology, impaired mechanotransduction, and altered gene regulation. The exploration of Nesprin's impact on dilated cardiomyopathy offers a promising avenue for therapeutic interventions aimed at ameliorating the disease. This review provides a comprehensive overview of recent advancements in understanding the pivotal role of Nesprins in dilated cardiomyopathy research.

Genotype is associated with left ventricular reverse remodelling and early events in recent-onset dilated cardiomyopathy

AIMS

Recent-onset dilated cardiomyopathy (RODCM) is characterized by heterogeneous aetiology and diverse clinical outcomes, with scarce data on genotype-phenotype correlates. Our aim was to correlate individual RODCM genotypes with left ventricular reverse remodelling (LVRR) and clinical outcomes.

METHODS AND RESULTS

In this prospective study, a total of 386 Czech RODCM patients with symptom duration ≤6 months underwent genetic counselling and whole-exome sequencing (WES). The presence of pathogenic (class 5) or likely pathogenic (class 4) variants in a set of 72 cardiomyopathy-related genes was correlated with the occurrence of all-cause death, heart transplantation, or implantation of a ventricular assist device (primary outcome) and/or ventricular arrhythmia event (secondary outcome). LVRR was defined as an improvement of left ventricular ejection fraction to >50% or ≥10% absolute increase, with a left ventricular end-diastolic diameter ≤33 mm/m2 or ≥10% relative decrease. Median follow-up was 41 months. RODCM was familial in 98 (25%) individuals. Class 4-5 variants of interest (VOIs) were identified in 125 (32%) cases, with 69 (18%) having a single titin-truncating variant (TTNtv) and 56 (14%) having non-titin (non-TTN) VOIs. The presence of class 4-5 non-TTN VOIs, but not of TTNtv, heralded a lower probability of 12-month LVRR and proved to be an independent baseline predictor both of the primary and the secondary outcome. The negative result of genetic testing was a strong protective baseline variable against occurrence of life-threatening ventricular arrhythmias. Detection of class 4-5 VOIs in genes coding nuclear envelope proteins was another independent predictor of both study outcomes at baseline and also of life-threatening ventricular arrhythmias after 12 months. Class 4-5 VOIs of genes coding cytoskeleton were associated with an increased risk of life-threatening ventricular arrhythmias after baseline assessment. A positive family history of dilated cardiomyopathy alone only related to a lower probability of LVRR at 12 months and at the final follow-up.

CONCLUSIONS

RODCM patients harbouring class 4-5 non-TTN VOIs are at higher risk of progressive heart failure and life-threatening ventricular arrhythmias. Genotyping may improve their early risk stratification at baseline assessment.

Genome-wide association study reveals mechanisms underlying dilated cardiomyopathy and myocardial resilience

Dilated cardiomyopathy (DCM) is a heart muscle disease that represents an important cause of morbidity and mortality, yet causal mechanisms remain largely elusive. Here, we perform a large-scale genome-wide association study and multitrait analysis for DCM using 9,365 cases and 946,368 controls. We identify 70 genome-wide significant loci, which show broad replication in independent samples and map to 63 prioritized genes. Tissue, cell type and pathway enrichment analyses highlight the central role of the cardiomyocyte and contractile apparatus in DCM pathogenesis. Polygenic risk scores constructed from our genome-wide association study predict DCM across different ancestry groups, show differing contributions to DCM depending on rare pathogenic variant status and associate with systolic heart failure across various clinical settings. Mendelian randomization analyses reveal actionable potential causes of DCM, including higher bodyweight and higher systolic blood pressure. Our findings provide insights into the genetic architecture and mechanisms underlying DCM and myocardial function more broadly.

Three Novel Pathogenic Variants in Unrelated Vietnamese Patients with Cardiomyopathy

Background: Cardiomyopathy, including dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM), is a major cause of heart failure (HF) and a leading indication for heart transplantation. Of these patients, 20-50% have a genetic cause, so understanding the genetic basis of cardiomyopathy will provide knowledge about the pathogenesis of the disease for diagnosis, treatment, prevention, and genetic counseling for families. Methods: This study collected nine patients from different Vietnamese families for genetic analysis at The Cardiovascular Center, E Hospital, Hanoi, Vietnam. The patients were diagnosed with cardiomyopathy based on clinical symptoms. Whole-exome sequencing (WES) was performed in the Vietnamese patients to identify variants associated with cardiomyopathy, and the Sanger sequencing method was used to validate the variants in the patients' families. The influence of the variants was predicted using in silico analysis tools. Results: Nine heterozygous variants were detected as a cause of disease in the patients, three of which were novel variants, including c.284C>G, p.Pro95Arg in the MYL2 gene, c.2356A>G, p.Thr786Ala in the MYH7 gene, and c.1223T>A, p.Leu408Gln in the DES gene. Two other variants were pathogenic variants (c.602T>C, p.Ile201Thr in the MYH7 gene and c.1391G>C, p.Gly464Ala in the PTPN11 gene), and four were variants of uncertain significance in the ACTA2, ANK2, MYOZ2, and PRKAG2 genes. The results of the in silico prediction software showed that the identified variants were pathogenic and responsible for the patients' DCM. Conclusions: Our results contribute to the understanding of cardiomyopathy pathogenesis and provide a basis for diagnosis, treatment, prevention, and genetic counseling.

Comparing HeartModelAI and cardiac magnetic resonance imaging for left ventricular volume and function evaluation in patients with dilated cardiomyopathy

BACKGROUND

Integration of artificial intelligence enhances precision, yielding dependable evaluations of left ventricular volumes and ejection fraction despite image quality variations. Commercial software like HeartModelAI provides fully automated 3DE quantification, simplifying the measurement of left chamber volumes and ejection fraction. In this manuscript, we present a cross-sectional study to assess and compare the diagnostic accuracy of automated 3D echocardiography (HeartModelAI) to the standard Cardiac Magnetic Resonance Imaging in patients with dilated cardiomyopathy.

METHODS

In this cross-sectional study, 30 patients with dilated cardiomyopathy referring to the Tehran Heart Center with cardiac magnetic resonance imaging and comprehensive 3D transthoracic echocardiography within 24 h were included. All 3D volume analysis was performed with fully automated quantification software (HeartModelAI) using 3D images of 2,3, and 4-chamber views at the end of systole and diastole.

RESULTS

Excellent Inter- and Intra-observer correlation coefficient was reported for HeartModelAI software for all indexes. HeartModelAI displayed a remarkable correlation with cardiac magnetic resonance for left ventricular end-systolic volume index (r = 0.918 and r = 0.911); nevertheless, it underestimated left ventricular end-systolic volume index and left ventricular end-diastolic volume index. Conversely, ejection fraction, stroke volume, and left ventricular mass were overestimated. It was found that manual contour correction can enhance the accuracy of automated model estimations, particularly concerning EF in participants needing correction.

CONCLUSION

HeartModelAI software emerges as a rapid and viable imaging approach for evaluating the left ventricle's structure and function. In our study, LV volumes assessed by HeartModelAI demonstrated strong correlations with cardiac magnetic resonance imaging.

BAG-3 Mutation Dilated Cardiomyopathy With Left Ventricular Noncompaction in Young Healthy Adult

Cardiomyopathies are generally divided into ischemic and nonischemic types. Dilated cardiomyopathies, which are a type of nonischemic cardiomyopathy, may have a trait of left ventricular noncompaction. We present the case of a 34-year-old man with new-onset decompensated heart failure and left ventricular noncompaction from a BAG3 (Bcl-2 associated athanogene 3) truncating mutation.

Downregulation of miR-214 promotes dilated Cardiomyopathy Progression through PDE5A-Mediated cGMP regulation

Dilated cardiomyopathy (DCM) is a myocardial disorder resulting in a substantial decline in cardiac function and potentially leading to heart failure. This research combines bioinformatics analysis with empirical validation to explore the roles and mechanisms of miR-214 in DCM. Using the DEseq2 R package, a total of 125 differentially expressed circulating miRNAs (DE c-miRNAs) and 784 DE genes (DEGs) were identified. Cross-analysis between target genes of DE c-miRNAs and DEGs identified 124 common genes, and protein-protein interaction analysis of common genes identified 11 hub genes. Twelve DE c-miRNAs were further verified by quantifying their levels in the serum of DCM patients and healthy individuals. miR-214 levels were significantly decreased in serum from DCM patients, positively correlated with left ventricular ejection fraction and left ventricular fractional shortening. Further analysis showed that miR-214 directly targets and negatively regulates phosphodiesterase 5 A (PDE5A). Elevated PDE5A expression reduced cGMP levels; however, using sildenafil, a PDE5A inhibitor, reversed this effect, substantiating the regulatory mechanism of miR-214 on cGMP via PDE5A. These results provide new potential targets for the diagnosis and treatment of DCM.

Dilated cardiomyopathy-associated skeletal muscle actin (ACTA1) mutation R256H disrupts actin structure and function and causes cardiomyocyte hypocontractility

Skeletal muscle actin (ACTA1) mutations are a prevalent cause of skeletal myopathies consistent with ACTA1's high expression in skeletal muscle. Rare de novo mutations in ACTA1 associated with combined cardiac and skeletal myopathies have been reported, but ACTA1 represents only ~20% of the total actin pool in cardiomyocytes, making its role in cardiomyopathy controversial. Here we demonstrate how a mutation in an actin isoform expressed at low levels in cardiomyocytes can cause cardiomyopathy by focusing on a unique ACTA1 variant, R256H. We previously identified this variant in a family with dilated cardiomyopathy, who had reduced systolic function without clinical skeletal myopathy. Using a battery of multiscale biophysical tools, we show that R256H has potent effects on ACTA1 function at the molecular scale and in human cardiomyocytes. Importantly, we demonstrate that R256H acts in a dominant manner, where the incorporation of small amounts of mutant protein into thin filaments is sufficient to disrupt molecular contractility, and that this effect is dependent on the presence of troponin and tropomyosin. To understand the structural basis of this change in regulation, we resolved a structure of R256H filaments using cryoelectron microscopy, and we see alterations in actin's structure that have the potential to disrupt interactions with tropomyosin. Finally, we show that ACTA1R256H/+ human-induced pluripotent stem cell cardiomyocytes demonstrate reduced contractility and sarcomeric organization. Taken together, we demonstrate that R256H has multiple effects on ACTA1 function that are sufficient to cause reduced contractility and establish a likely causative relationship between ACTA1 R256H and clinical cardiomyopathy.

Respiratory Muscle Strength and Quality of Life in Patients With Heart Failure and Their Main Correlated Factors: A Cross-sectional Study

BACKGROUND

Heart failure may cause peripheral and respiratory muscle alterations, dyspnea, fatigue, and exercise intolerance, worsening the quality of life of patients.

OBJECTIVES

The aims of this study were to analyze respiratory muscle strength and quality of life of patients with heart failure and correlate them with clinical variables and functional classification.

METHODS

This cross-sectional study involved patients with heart failure. A manovacuometer assessed maximum inspiratory and expiratory pressures, and quality of life was assessed using the Minnesota Living with Heart Failure Questionnaire. Functional classification was categorized according to the New York Heart Association (NYHA) class in I, II, III, or IV.

RESULTS

We included 60 patients (66.7% male) with a mean age of 62.0 years and mean left ventricular ejection fraction of 42.0%. Maximum inspiratory pressure and maximum expiratory pressure were close to normal (>70% of predicted) in most patients; however, a subgroup composed mostly of patients with dilated heart failure and NYHA class III (n = 21) presented low maximum inspiratory pressure values (59.2%; 95% confidence interval, 55.7%-62.8%). The mean total score of the Minnesota Living with Heart Failure Questionnaire was 44.4 points, being negatively correlated with left ventricular ejection fraction ( r = -0.29, P = .02). Patients with NYHA class III and disease duration longer than 120 months presented higher total ( P < .01) and physical dimension scores.

CONCLUSIONS

Most patients had respiratory muscle strength close to normal; however, those with dilated heart failure and NYHA class III presented low maximum inspiratory pressure values. Quality of life was moderately compromised, mainly because of long disease duration, NYHA class III, and low left ventricular ejection fraction.

Cardiomyopathy: pathogenesis and therapeutic interventions

Cardiomyopathy is a group of disease characterized by structural and functional damage to the myocardium. The etiologies of cardiomyopathies are diverse, spanning from genetic mutations impacting fundamental myocardial functions to systemic disorders that result in widespread cardiac damage. Many specific gene mutations cause primary cardiomyopathy. Environmental factors and metabolic disorders may also lead to the occurrence of cardiomyopathy. This review provides an in-depth analysis of the current understanding of the pathogenesis of various cardiomyopathies, highlighting the molecular and cellular mechanisms that contribute to their development and progression. The current therapeutic interventions for cardiomyopathies range from pharmacological interventions to mechanical support and heart transplantation. Gene therapy and cell therapy, propelled by ongoing advancements in overarching strategies and methodologies, has also emerged as a pivotal clinical intervention for a variety of diseases. The increasing number of causal gene of cardiomyopathies have been identified in recent studies. Therefore, gene therapy targeting causal genes holds promise in offering therapeutic advantages to individuals diagnosed with cardiomyopathies. Acting as a more precise approach to gene therapy, they are gradually emerging as a substitute for traditional gene therapy. This article reviews pathogenesis and therapeutic interventions for different cardiomyopathies.

[A clinical case of reverse left ventricular remodeling in patient with pathogenic TTN mutation. Case report]

Dilated cardiomyopathy (DCM) is a leading cause of heart failure, sudden cardiac death, and heart transplantation in young patients. The causes of DCM are varied and include genetic factors and metabolic, infectious, toxic and others factors. Today it is known that germline mutations in more than 98 genes can be associated with the occurrence of DCM. However, the penetrance of these genes often depends on a combination of factors, including modifiable ones, i.e. those that change under the influence of the environment. About 20-25% of genetically determined forms of DCM are due to mutations in the titin gene (TTN). Titin is the largest protein in the body, which is an important component of the sarcomer. Although titin is the largest protein in the human body, its role in the physiology of heart and disease is not yet fully understood. However, a mutation in the TTN gene may later represent a potential therapeutic target for genetic and acquired cardiomyopathy. Thus, the analysis of clinical cases of cardiomyopathy in patients with identified mutations in the TTN gene is of great scientific interest. The article presents a clinical case of manifestation of DCM in patient with a revealed pathogenic variant of mutation in the gene TTN and reverse left ventricular remodeling of the against the background of optimal therapy of heart failure in a subsequent outpatient observation.

Integrative proteomic and metabolomic elucidation of cardiomyopathy with in vivo and in vitro models and clinical samples

Cardiomyopathy is a prevalent cardiovascular disease that affects individuals of all ages and can lead to life-threatening heart failure. Despite its variety in types, each with distinct characteristics and causes, our understanding of cardiomyopathy at a systematic biology level remains incomplete. Mass spectrometry-based techniques have emerged as powerful tools, providing a comprehensive view of the molecular landscape and aiding in the discovery of biomarkers and elucidation of mechanisms. This review highlights the significant potential of integrating proteomic and metabolomic approaches with specialized databases to identify biomarkers and therapeutic targets across different types of cardiomyopathies. In vivo and in vitro models, such as genetically modified mice, patient-derived or induced pluripotent stem cells, and organ chips, are invaluable in exploring the pathophysiological complexities of this disease. By integrating omics approaches with these sophisticated modeling systems, our comprehension of the molecular underpinnings of cardiomyopathy can be greatly enhanced, facilitating the development of diagnostic markers and therapeutic strategies. Among the promising therapeutic targets are those involved in extracellular matrix remodeling, sarcomere damage, and metabolic remodeling. These targets hold the potential to advance precision therapy in cardiomyopathy, offering hope for more effective treatments tailored to the specific molecular profiles of patients.

SIRT1 Ameliorates Lamin A/C Deficiency-Induced Cardiac Dysfunction by Promoting Mitochondrial Bioenergetics

Dilated cardiomyopathy (DCM) is associated with high mortality despite advanced therapies. The LMNA gene encodes lamin A/C and is the second most frequently mutated gene associated with DCM, for which therapeutic options are limited. Here we generated Lmna -/- mice and found they exhibited cardiac dysfunction at the age of 1 month but not at 2 weeks. Proteomics showed down-regulation of mitochondrial function-related pathways in Lmna -/- hearts. Moreover, early injured mitochondria with decreased cristae density and sirtuin 1 (SIRT1) down-regulation were observed in 2-week-old Lmna -/- hearts. Adenoviral overexpression of SIRT1 in lamin A/C knockdown neonatal rat ventricular myocytes improved mitochondrial oxidative respiration capacity. Adeno-associated virus-mediated SIRT1 overexpression alleviated mitochondrial injury, cardiac systolic dysfunction, ventricular dilation, and fibrosis, and prolonged lifespan in Lmna -/- mice. Mechanistically, LMNA maintains mitochondrial bioenergetics through the SIRT1-PARKIN axis. Our results suggest that targeting the SIRT1 signaling pathway is expected to be a novel therapeutic strategy for LMNA mutation-associated DCM.

LncRNA DCRT Protects Against Dilated Cardiomyopathy by Preventing NDUFS2 Alternative Splicing by Binding to PTBP1

BACKGROUND

Dilated cardiomyopathy is characterized by left ventricular dilation and continuous systolic dysfunction. Mitochondrial impairment is critical in dilated cardiomyopathy; however, the underlying mechanisms remain unclear. Here, we explored the cardioprotective role of a heart-enriched long noncoding RNA, the dilated cardiomyopathy repressive transcript (DCRT), in maintaining mitochondrial function.

METHODS

The DCRT knockout (DCRT-/-) mice and DCRT knockout cells were developed using CRISPR-Cas9 technology. Cardiac-specific DCRT transgenic mice were generated using α-myosin heavy chain promoter. Chromatin coimmunoprecipitation, RNA immunoprecipitation, Western blot, and isoform sequencing were performed to investigate the underlying mechanisms.

RESULTS

We found that the long noncoding RNA DCRT was highly enriched in the normal heart tissues and that its expression was significantly downregulated in the myocardium of patients with dilated cardiomyopathy. DCRT-/- mice spontaneously developed cardiac dysfunction and enlargement with mitochondrial impairment. DCRT transgene or overexpression with the recombinant adeno-associated virus system in mice attenuated cardiac dysfunction induced by transverse aortic constriction treatment. Mechanistically, DCRT inhibited the third exon skipping of NDUFS2 (NADH dehydrogenase ubiquinone iron-sulfur protein 2) by directly binding to PTBP1 (polypyrimidine tract binding protein 1) in the nucleus of cardiomyocytes. Skipping of the third exon of NDUFS2 induced mitochondrial dysfunction by competitively inhibiting mitochondrial complex I activity and binding to PRDX5 (peroxiredoxin 5) and suppressing its antioxidant activity. Furthermore, coenzyme Q10 partially alleviated mitochondrial dysfunction in cardiomyocytes caused by DCRT reduction.

CONCLUSIONS

Our study revealed that the loss of DCRT contributed to PTBP1-mediated exon skipping of NDUFS2, thereby inducing cardiac mitochondrial dysfunction during dilated cardiomyopathy development, which could be partially treated with coenzyme Q10 supplementation.

Leiomodin 2 neonatal dilated cardiomyopathy mutation results in altered actin gene signatures and cardiomyocyte dysfunction

Neonatal dilated cardiomyopathy (DCM) is a poorly understood muscular disease of the heart. Several homozygous biallelic variants in LMOD2, the gene encoding the actin-binding protein Leiomodin 2, have been identified to result in severe DCM. Collectively, LMOD2-related cardiomyopathies present with cardiac dilation and decreased heart contractility, often resulting in neonatal death. Thus, it is evident that Lmod2 is essential to normal human cardiac muscle function. This study aimed to understand the underlying pathophysiology and signaling pathways related to the first reported LMOD2 variant (c.1193 G > A, p.Trp398*). Using patient-specific human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and a mouse model harboring the homologous mutation to the patient, we discovered dysregulated actin-thin filament lengths, altered contractility and calcium handling properties, as well as alterations in the serum response factor (SRF)-dependent signaling pathway. These findings reveal that LMOD2 may be regulating SRF activity in an actin-dependent manner and provide a potential new strategy for the development of biologically active molecules to target LMOD2-related cardiomyopathies.