Implications of Genetic Testing in Dilated Cardiomyopathy

Actn2 defects accelerates H9c2 hypertrophy via ERK phosphorylation under chronic stress

BACKGROUND

In humans, ACTN2 mutations are identified as highly relevant to a range of cardiomyopathies such as DCM and HCM, while their association with sudden cardiac death has been observed in forensic cases. Although ACTN2 has been shown to regulate sarcomere Z-disc organization, a causal relationship between ACTN2 dysregulation and cardiomyopathies under chronic stress has not yet been investigated.

OBJECTIVE

In this work, we explored the relationship between Actn2 dysregulation and cardiomyopathies under dexamethasone treatment.

METHODS

Previous cases of ACTN2 mutations were collected and the conservative analysis was carried out by MEGA 11, the possible impact on the stability and function of ACTN2 affected by these mutations was predicted by Polyphen-2. ACTN2 was suppressed by siRNA in H9c2 cells under dexamethasone treatment to mimic the chronic stress in vitro. Then the cardiac hypertrophic molecular biomarkers were elevated, and the potential pathways were explored by transcriptome analysis.

RESULTS

Actn2 suppression impaired calcium uptake and increased hypertrophy in H9c2 cells under dexamethasone treatment. Concomitantly, hypertrophic molecular biomarkers were also elevated in Actn2-suppressed cells. Further transcriptome analysis and Western blotting data suggested that Actn2 suppression led to the excessive activation of the MAPK pathway and ERK cascade. In vitro pharmaceutical intervention with ERK inhibitors could partially reverse the morphological changes and inhibit the excessive cardiac hypertrophic molecular biomarkers in H9c2 cells.

CONCLUSION

Our study revealed a functional role of ACTN2 under chronic stress, loss of ACTN2 function accelerated H9c2 hypertrophy through ERK signaling. A commercial drug, Ibudilast, was identified to reverse cell hypertrophy in vitro.

Quality of life and societal costs in patients with dilated cardiomyopathy

AIMS

Dilated cardiomyopathy (DCM) is a major cause of heart failure impairing patient wellbeing and imposing a substantial economic burden on society, but respective data are missing. This study aims to measure the quality of life (QoL) and societal costs of DCM patients.

METHODS AND RESULTS

A cross-sectional evaluation of QoL and societal costs of DCM patients was performed through the 5-level EuroQol and the Medical Consumption Questionnaire and Productivity Cost Questionnaire, respectively. QoL was translated into numerical values (i.e. utilities). Costs were measured from a Dutch societal perspective. Final costs were extrapolated to 1 year, reported in 2022 Euros, and compared between DCM severity according to NYHA classes. A total of 550 DCM patients from the Maastricht cardiomyopathy registry were included. Mean age was 61 years, and 34% were women. Overall utility was slightly lower for DCM patients than the population mean (0.840 vs. 0.869, P = 0.225). Among EQ-5D dimensions, DCM patients scored lowest in 'usual activities'. Total societal DCM costs were €14 843 per patient per year. Cost drivers were productivity losses (€7037) and medical costs (€4621). Patients with more symptomatic DCM (i.e. NYHA class III or IV) had significantly higher average DCM costs per year compared to less symptomatic DCM (€31 099 vs. €11 446, P < 0.001) and significantly lower utilities (0.631 vs. 0.883, P < 0.001).

CONCLUSION

DCM is associated with high societal costs and reduced QoL, in particular with high DCM severity.

Navigating the penetrance and phenotypic spectrum of inherited cardiomyopathies

Inherited cardiomyopathies are genetic diseases that can lead to heart failure and sudden cardiac death. These conditions tend to run in families, following an autosomal dominant pattern where first-degree relatives have a 50% chance of carrying the pathogenic variant. Despite significant advancements and increased accessibility of genetic testing, accurately predicting the phenotypic expression of these conditions remains challenging due to the inherent variability in their clinical manifestations and the incomplete penetrance observed. This poses challenges in providing patient care and effectively communicating the potential risk of future disease to patients and their families. To address these challenges, this review aims to synthesize the available evidence on penetrance, expressivity, and factors influencing disease expression to improve communication and risk assessment for patients with inherited cardiomyopathies and their family members.

A novel BAG5 variant impairs the ER stress response pathway, causing dilated cardiomyopathy and arrhythmia

Pathogenic BAG5 variants recently linked to dilated cardiomyopathy (DCM) prompt further investigation into phenotypic, mutational, and pathomechanistic aspects. We explored the clinical and molecular characteristics of DCM associated with BAG5 variants, uncovering the consistently severe manifestations of the disease and its impact on the endoplasmic reticulum (ER) stress response. The analysis involved three siblings affected by DCM and arrhythmia, along with their four unaffected siblings, their unaffected father, and their mother who exhibited arrhythmia. The parents were consanguineous. Exome and Sanger sequencing identified a novel BAG5 variant, c.444_445delGA (p.Lys149AsnfsTer6), homozygous in affected siblings and heterozygous in parents and unaffected siblings. We generated heterozygous and homozygous Bag5 point mutant knock-in (KI) mice and evaluated cardiac pathophysiology under stress conditions, including tunicamycin (TN) administration. Bag5-/- mice displayed no abnormalities up to 12 months old and showed no anomalies during an exercise stress test. However, following TN injection, Bag5-/- mice exhibited significantly reduced left ventricular fractional shortening (LVFS) and ejection fraction (LVEF). Their cardiac tissues exhibited a notable increase in apoptotic cells, despite non-distinctive changes in CHOP and GRP78 levels. Interestingly, only Bag5 KI male mice demonstrated arrhythmia, which was more pronounced in Bag5-/- than in Bag5+/-males. Here, our study reveals a novel BAG5 mutation causing DCM by impairing the ER stress response, with observed sex-specific arrhythmia differences.

Genome-first evaluation with exome sequence and clinical data uncovers underdiagnosed genetic disorders in a large healthcare system

Population-based genomic screening may help diagnose individuals with disease-risk variants. Here, we perform a genome-first evaluation for nine disorders in 29,039 participants with linked exome sequences and electronic health records (EHRs). We identify 614 individuals with 303 pathogenic/likely pathogenic or predicted loss-of-function (P/LP/LoF) variants, yielding 644 observations; 487 observations (76%) lack a corresponding clinical diagnosis in the EHR. Upon further investigation, 75 clinically undiagnosed observations (15%) have evidence of symptomatic untreated disease, including familial hypercholesterolemia (3 of 6 [50%] undiagnosed observations with disease evidence) and breast cancer (23 of 106 [22%]). These genetic findings enable targeted phenotyping that reveals new diagnoses in previously undiagnosed individuals. Disease yield is greater with variants in penetrant genes for which disease is observed in carriers in an independent cohort. The prevalence of P/LP/LoF variants exceeds that of clinical diagnoses, and some clinically undiagnosed carriers are discovered to have disease. These results highlight the potential of population-based genomic screening.

Penetrance of Dilated Cardiomyopathy in Genotype-Positive Relatives

BACKGROUND

Disease penetrance in genotype-positive (G+) relatives of families with dilated cardiomyopathy (DCM) and the characteristics associated with DCM onset in these individuals are unknown.

OBJECTIVES

This study sought to determine the penetrance of new DCM diagnosis in G+ relatives and to identify factors associated with DCM development.

METHODS

The authors evaluated 779 G+ patients (age 35.8 ± 17.3 years; 459 [59%] females; 367 [47%] with variants in TTN) without DCM followed at 25 Spanish centers.

RESULTS

After a median follow-up of 37.1 months (Q1-Q3: 16.3-63.8 months), 85 individuals (10.9%) developed DCM (incidence rate of 2.9 per 100 person-years; 95% CI: 2.3-3.5 per 100 person-years). DCM penetrance and age at DCM onset was different according to underlying gene group (log-rank P = 0.015 and P <0.01, respectively). In a multivariable model excluding CMR parameters, independent predictors of DCM development were: older age (HR per 1-year increase: 1.02; 95% CI: 1.0-1.04), an abnormal electrocardiogram (HR: 2.13; 95% CI: 1.38-3.29); presence of variants in motor sarcomeric genes (HR: 1.92; 95% CI: 1.05-3.50); lower left ventricular ejection fraction (HR per 1% increase: 0.86; 95% CI: 0.82-0.90) and larger left ventricular end-diastolic diameter (HR per 1-mm increase: 1.10; 95% CI: 1.06-1.13). Multivariable analysis in individuals with cardiac magnetic resonance and late gadolinium enhancement assessment (n = 360, 45%) identified late gadolinium enhancement as an additional independent predictor of DCM development (HR: 2.52; 95% CI: 1.43-4.45).

CONCLUSIONS

Following a first negative screening, approximately 11% of G+ relatives developed DCM during a median follow-up of 3 years. Older age, an abnormal electrocardiogram, lower left ventricular ejection fraction, increased left ventricular end-diastolic diameter, motor sarcomeric genetic variants, and late gadolinium enhancement are associated with a higher risk of developing DCM.

Clinical Guideline for Preimplantation Genetic Testing in Inherited Cardiac Diseases

BACKGROUND

Preimplantation genetic testing (PGT) is a reproductive technology that selects embryos without (familial) genetic variants. PGT has been applied in inherited cardiac disease and is included in the latest American Heart Association/American College of Cardiology guidelines. However, guidelines selecting eligible couples who will have the strongest risk reduction most from PGT are lacking. We developed an objective decision model to select eligibility for PGT and compared its results with those from a multidisciplinary team.

METHODS

All couples with an inherited cardiac disease referred to the national PGT center were included. A multidisciplinary team approved or rejected the indication based on clinical and genetic information. We developed a decision model based on published risk prediction models and literature, to evaluate the severity of the cardiac phenotype and the penetrance of the familial variant in referred patients. The outcomes of the model and the multidisciplinary team were compared in a blinded fashion.

RESULTS

Eighty-three couples were referred for PGT (1997-2022), comprising 19 different genes for 8 different inherited cardiac diseases (cardiomyopathies and arrhythmias). Using our model and proposed cutoff values, a definitive decision was reached for 76 (92%) couples, aligning with 95% of the multidisciplinary team decisions. In a prospective cohort of 11 couples, we showed the clinical applicability of the model to select couples most eligible for PGT.

CONCLUSIONS

The number of PGT requests for inherited cardiac diseases increases rapidly, without the availability of specific guidelines. We propose a 2-step decision model that helps select couples with the highest risk reduction for cardiac disease in their offspring after PGT.

Role of genetics in inflammatory cardiomyopathy

Traditional cardiomyopathy paradigms segregate inflammatory etiologies from those caused by genetic variants. An identified or presumed trigger is implicated in acute myocarditis or chronic inflammatory cardiomyopathy but growing evidence suggests a significant proportion of patients have an underlying cardiomyopathy-associated genetic variant often even when a clear inflammatory trigger is identified. Recognizing a possible genetic contribution to inflammatory cardiomyopathy may have major downstream implications for both the patient and family. The presenting features of myocarditis (i.e. chest pain, arrhythmia, and/or heart failure) may provide insight into diagnostic considerations. One example is isolated cardiac sarcoidosis, a distinct inflammatory cardiomyopathy that carries diagnostic challenges and clinical overlap; genetic testing has increasingly reclassified cases of isolated cardiac sarcoidosis as genetic cardiomyopathy, notably altering management. On the other side, inflammatory presentations of genetic cardiomyopathies are likewise underappreciated and a growing area of investigation. Inflammation plays an important role in the pathogenesis of several familial cardiomyopathies, especially arrhythmogenic phenotypes. Given these clinical scenarios, and the implications on clinical decision making such as initiation of immunosuppression, sudden cardiac death prevention, and family screening, it is important to recognize when genetics may be playing a role.

Exploring TTN variants as genetic insights into cardiomyopathy pathogenesis and potential emerging clues to molecular mechanisms in cardiomyopathies

The giant protein titin (TTN) is a sarcomeric protein that forms the myofibrillar backbone for the components of the contractile machinery which plays a crucial role in muscle disorders and cardiomyopathies. Diagnosing TTN pathogenic variants has important implications for patient management and genetic counseling. Genetic testing for TTN variants can help identify individuals at risk for developing cardiomyopathies, allowing for early intervention and personalized treatment strategies. Furthermore, identifying TTN variants can inform prognosis and guide therapeutic decisions. Deciphering the intricate genotype-phenotype correlations between TTN variants and their pathologic traits in cardiomyopathies is imperative for gene-based diagnosis, risk assessment, and personalized clinical management. With the increasing use of next-generation sequencing (NGS), a high number of variants in the TTN gene have been detected in patients with cardiomyopathies. However, not all TTN variants detected in cardiomyopathy cohorts can be assumed to be disease-causing. The interpretation of TTN variants remains challenging due to high background population variation. This narrative review aimed to comprehensively summarize current evidence on TTN variants identified in published cardiomyopathy studies and determine which specific variants are likely pathogenic contributors to cardiomyopathy development.

The Expansion of Genetic Testing in Cardiovascular Medicine: Preparing the Cardiology Community for the Changing Landscape

PURPOSE OF REVIEW

Pathogenic DNA variants underlie many cardiovascular disease phenotypes. The most well-recognized of these include familial dyslipidemias, cardiomyopathies, arrhythmias, and aortopathies. The clinical presentations of monogenic forms of cardiovascular disease are often indistinguishable from those with complex genetic and non-genetic etiologies, making genetic testing an essential aid to precision diagnosis.

RECENT FINDINGS

Precision diagnosis enables efficient management, appropriate use of emerging targeted therapies, and follow-up of at-risk family members. Genetic testing for these conditions is widely available but under-utilized. In this review, we summarize the potential benefits of genetic testing, highlighting the specific cardiovascular disease phenotypes in which genetic testing should be considered, and how clinicians can integrate guideline-directed genetic testing into their practice.

[Genetic basis of atrial fibrillation-on the road to precision medicine]

Atrial fibrillation (AF) is the most common cardiac arrhythmia and has complex genetic underpinnings. Despite advancements in treatment, mortality of AF patients remains high. This review discusses the genetic basis of AF and its implications for diagnosis and therapy. Although AF pathology has long been known to include a hereditary component, the first genes associated with AF were not identified until the early 2000s. Subsequent research with genome-wide association studies (GWAS) has implicated other genes and numerous genetic variants in AF. These studies have revealed nearly 140 different regions in the DNA with genome-wide significance associated with AF. In addition to common variants, rare variants with large effects have also been identified. The integration of these genetic findings into clinical practice holds promise for improving AF diagnosis and treatment, moving us closer to precision medicine. However, challenges remain, including the need for more diverse genetic data of non-European ancestry and improved genetic analyses of responses to AF therapy.

Genetic Characterization of Dilated Cardiomyopathy in Romanian Adult Patients

Dilated cardiomyopathy (DCM) represents a group of disorders affecting the structure and function of the heart muscle, leading to a high risk of heart failure and sudden cardiac death (SCD). DCM frequently involves an underlying genetic etiology. Genetic testing is valuable for risk stratification, treatment decisions, and family screening. Romanian population data on the genetic etiology of DCM are lacking. We aimed to investigate the genetic causes for DCM among Romanian adult patients at tertiary referral centers across the country. Clinical and genetic investigations were performed on adult patients presenting to tertiary hospitals in Romania. The genetic investigations used next-generation sequencing panels of disease-associated DCM genes. A total of 122 patients with DCM underwent genetic testing. The mean age at DCM diagnosis was 41.6 ± 12.4 years. The genetic investigations identified pathogenic or likely pathogenic variants in 50.8% of participants, while 25.4% had variants of unknown significance. Disease-causing variants in 15 genes were identified in people with DCM, with 31 previously unreported variants. Variants in TTN, LMNA, and DSP explained 75% of genetic causes for DCM. In total, 52.4% of patients had a family history of DCM/SCD. Left ventricular ejection fraction of <35% was observed in 41.9% of patients with disease-causing variants and 55% with negative or uncertain findings. Further genotype-phenotype correlations were explored in this study population. The substantial percentage (50.8%) of disease-causing variants identified in patients with DCM acknowledges the importance of genetic investigations. This study highlights the genetic landscape in genes associated with DCM in the Romanian population.

Prioritizing the primary prevention of heart failure: Measuring, modifying and monitoring risk

With the rising incidence of heart failure (HF) and increasing burden of morbidity, mortality, and healthcare expenditures, primary prevention of HF targeting individuals in at-risk HF (Stage A) and pre-HF (Stage B) Stages has become increasingly important with the goal to decrease progression to symptomatic (Stage C) HF. Identification of risk based on traditional risk factors (e.g., cardiovascular health which can be assessed with the American Heart Association's Life's Essential 8 framework), adverse social determinants of health, inherited risk of cardiomyopathies, and identification of risk-enhancing factors, such as patients with viral disease, exposure to cardiotoxic chemotherapy, and history of adverse pregnancy outcomes should be the first step in evaluation for HF risk. Next, use of guideline-endorsed risk prediction tools such as Pooled Cohort Equations to Prevent Heart Failure provide quantification of absolute risk of HF based in traditional risk factors. Risk reduction through counseling on traditional risk factors is a core focus of implementation of prevention and may include the use of novel therapeutics that target specific pathways to reduce risk of HF, such as mineralocorticoid receptor agonists (e.g., fineronone), angiotensin-receptor/neprolysin inhibitors, and sodium glucose co-transporter-2 inhibitors. These interventions may be limited in at-risk populations who experience adverse social determinants and/or individuals who reside in rural areas. Thus, strategies like telemedicine may improve access to preventive care. Gaps in the current knowledge base for risk-based prevention of HF are highlighted to outline future research that may target approaches for risk assessment and risk-based prevention with the use of artificial intelligence, genomics-enhanced strategies, and pragmatic trials to develop a guideline-directed medical therapy approach to reduce risk among individuals with Stage A and Stage B HF.

Titin domains with reduced core hydrophobicity cause dilated cardiomyopathy

The underlying genetic defect in most cases of dilated cardiomyopathy (DCM), a common inherited heart disease, remains unknown. Intriguingly, many patients carry single missense variants of uncertain pathogenicity targeting the giant protein titin, a fundamental sarcomere component. To explore the deleterious potential of these variants, we first solved the wild-type and mutant crystal structures of I21, the titin domain targeted by pathogenic variant p.C3575S. Although both structures are remarkably similar, the reduced hydrophobicity of deeply buried position 3575 strongly destabilizes the mutant domain, a scenario supported by molecular dynamics simulations and by biochemical assays that show no disulfide involving C3575. Prompted by these observations, we have found that thousands of similar hydrophobicity-reducing variants associate specifically with DCM. Hence, our results imply that titin domain destabilization causes DCM, a conceptual framework that not only informs pathogenicity assessment of gene variants but also points to therapeutic strategies counterbalancing protein destabilization.

Phenotypic variability of filamin C-related cardiomyopathy: Insights from a novel Dutch founder variant

BACKGROUND

Dilated cardiomyopathy (DCM) can be caused by truncating variants in the filamin C gene (FLNC). A new pathogenic FLNC variant, c.6864_6867dup, p.(Val2290Argfs∗23), was recently identified in Dutch patients with DCM.

OBJECTIVES

The report aimed to evaluate the phenotype of FLNC variant carriers and to determine whether this variant is a founder variant.

METHODS

Clinical and genetic data were retrospectively collected from variant carriers. Cardiovascular magnetic resonance studies were reassessed. Haplotypes were reconstructed to determine a founder effect. The geographical distribution and age of the variant were determined.

RESULTS

Thirty-three individuals (of whom 23 [70%] were female) from 9 families were identified. Sudden cardiac death was the first presentation in a carrier at the age of 28 years. The median age at diagnosis was 41 years (range 19-67 years). The phenotype was heterogeneous. DCM with left ventricular dilation and reduced ejection fraction (<45%) was present in 11 (33%) individuals, 3 (9%) of whom underwent heart transplantation. Cardiovascular magnetic resonance showed late gadolinium enhancement in 13 (65%) of the assessed individuals, primarily in a ringlike distribution. Nonsustained ventricular arrhythmias were detected in 6 (18%), and 5 (15%) individuals received an implantable cardioverter-defibrillator. A shared haplotype spanning 2.1 Mb was found in all haplotyped individuals. The variant originated between 275 and 650 years ago.

CONCLUSION

The pathogenic FLNC variant c.6864_6867dup, p.(Val2290Argfs∗23) is a founder variant originating from the south of the Netherlands. Carriers are susceptible to developing heart failure and ventricular arrhythmias. The cardiac phenotype is characterized by ringlike late gadolinium enhancement, even in individuals without significantly reduced left ventricular function.

Genetic Contribution to End-Stage Cardiomyopathy Requiring Heart Transplantation

BACKGROUND

Many cardiovascular disorders propel the development of advanced heart failure that necessitates cardiac transplantation. When treatable causes are excluded, studies to define causes are often abandoned, resulting in a diagnosis of end-stage idiopathic cardiomyopathy. We studied whether DNA sequence analyses could identify unrecognized causes of end-stage nonischemic cardiomyopathy requiring heart transplantation and whether the prevalence of genetic causes differed from ambulatory cardiomyopathy cases.

METHODS

We performed whole exome and genome sequencing of 122 explanted hearts from 101 adult and 21 pediatric patients with idiopathic cardiomyopathy from a single center. Data were analyzed for pathogenic/likely pathogenic variants in nuclear and mitochondrial genomes and assessed for nonhuman microbial sequences. The frequency of damaging genetic variants was compared among cardiomyopathy cohorts with different clinical severity.

RESULTS

Fifty-four samples (44.3%) had pathogenic/likely pathogenic cardiomyopathy gene variants. The frequency of pathogenic variants was similar in pediatric (42.9%) and adult (43.6%) samples, but the distribution of mutated genes differed (P=8.30×10-4). The prevalence of causal genetic variants was significantly higher in end-stage than in previously reported ambulatory adult dilated cardiomyopathy cases (P<0.001). Among remaining samples with unexplained causes, no damaging mitochondrial variants were identified, but 28 samples contained parvovirus genome sequences, including 2 samples with 6- to 9-fold higher levels than the overall mean levels in other samples.

CONCLUSIONS

Pathogenic variants and viral myocarditis were identified in 45.9% of patients with unexplained end-stage cardiomyopathy. Damaging gene variants are significantly more frequent among transplant compared with patients with ambulatory cardiomyopathy. Genetic analyses can help define cause of end-stage cardiomyopathy to guide management and risk stratification of patients and family members.

Diagnostic yield of genetic testing in a multinational heterogeneous cohort of 2088 DCM patients

Background

Familial dilated cardiomyopathy (DCM) causes heart failure and may lead to heart transplantation. DCM is typically a monogenic disorder with autosomal dominant inheritance. Currently disease-causing variants have been reported in over 60 genes that encode proteins in sarcomeres, nuclear lamina, desmosomes, cytoskeleton, and mitochondria. Over half of the patients undergoing comprehensive genetic testing are left without a molecular diagnosis even when patient selection follows strict DCM criteria.

Methods and results

This study was a retrospective review of patients referred for genetic testing at Blueprint Genetics due to suspected inherited DCM. Next generation sequencing panels included 23-316 genes associated with cardiomyopathies and other monogenic cardiac diseases. Variants were considered diagnostic if classified as pathogenic (P) or likely pathogenic (LP). Of the 2,088 patients 514 (24.6%) obtained a molecular diagnosis; 534 LP/P variants were observed across 45 genes, 2.7% (14/514) had two diagnostic variants in dominant genes. Nine copy number variants were identified: two multigene and seven intragenic. Diagnostic variants were observed most often in TTN (45.3%), DSP (6.7%), LMNA (6.7%), and MYH7 (5.2%). Clinical characteristics independently associated with molecular diagnosis were: a lower age at diagnosis, family history of DCM, paroxysmal atrial fibrillation, absence of left bundle branch block, and the presence of an implantable cardioverter-defibrillator.

Conclusions

Panel testing provides good diagnostic yield in patients with clinically suspected DCM. Causative variants were identified in 45 genes. In minority, two diagnostic variants were observed in dominant genes. Our results support the use of genetic panels in clinical settings in DCM patients with suspected genetic etiology.

The Genetic Evaluation of Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is a common cause of heart failure and is the primary indication for heart transplantation. A genetic etiology can be found in 20-35% of patients with DCM, especially in those with a family history of cardiomyopathy or sudden cardiac death at an early age. With advancements in genome sequencing, the understanding of genotype-phenotype relationships in DCM has expanded with over 60 genes implicated in the disease. Subsequently, these findings have increased adoption of genetic testing in the management of DCM, which has allowed for improved risk stratification and identification of at risk family members. In this review, we discuss the genetic evaluation of DCM with a focus on practical genetic testing considerations, genotype-phenotype associations, and insights into upcoming personalized therapies.

Comparative Efficacy of Different Drugs for the Treatment of Dilated Cardiomyopathy: A Systematic Review and Network Meta-analysis

BACKGROUND AND OBJECTIVE

At present, the therapies of dilated cardiomyopathy concentrated on the symptoms of heart failure and related complications. The study is to evaluate the clinical efficacy of a combination of various conventional and adjuvant drugs in treating dilated cardiomyopathy via network meta-analysis.

METHODS

The study was reported according to the PRISMA 2020 statement. From inception through 27 June 2022, the PubMed, Embase, Cochrane library, and Web of Science databases were searched for randomized controlled trials on medicines for treating dilated cardiomyopathy. The quality of the included studies was evaluated according to the Cochrane risk of bias assessment. R4.1.3 and Revman5.3 software were used for analysis.

RESULTS

There were 52 randomized controlled trials in this study, with a total of 25 medications and a sample size of 3048 cases. The network meta-analysis found that carvedilol, verapamil, and trimetazidine were the top three medicines for improving left ventricular ejection fraction (LVEF). Ivabradine, bucindolol, and verapamil were the top 3 drugs for improving left ventricular end-diastolic dimension (LVEDD). Ivabradine, L-thyroxine, and atorvastatin were the top 3 drugs for improving left ventricular end-systolic dimension (LVESD). Trimetazidine, pentoxifylline, and bucindolol were the top 3 drugs for improving the New York Heart Association classification (NYHA) cardiac function score. Ivabradine, carvedilol, and bucindolol were the top 3 drugs for reducing heart rate (HR).

CONCLUSION

A combination of different medications and conventional therapy may increase the clinical effectiveness of treating dilated cardiomyopathy. Beta-blockers, especially carvedilol, can improve ventricular remodeling, cardiac function, and clinical efficacy in patients with dilated cardiomyopathy (DCM). Hence, they can be used if patients tolerate them. If LVEF and HR do not meet the standard, ivabradine can also be used in combination with other treatments. However, since the quality and number of studies in our research were limited, large sample size, multi-center, and high-quality randomized controlled trials are required to corroborate our findings.

Clinical characteristics of heart failure with reduced ejection fraction patients with rare pathogenic variants in dilated cardiomyopathy-associated genes: A subgroup analysis of the PARADIGM-HF trial

AIMS

To evaluate the prevalence of pathogenic variants in genes associated with dilated cardiomyopathy (DCM) in a clinical trial population with heart failure and reduced ejection fraction (HFrEF) and describe the baseline characteristics by variant carrier status.

METHODS AND RESULTS

This was a post hoc analysis of the Phase 3 PARADIGM-HF trial. Forty-four genes, divided into three tiers, based on definitive, moderate or limited evidence of association with DCM, were assessed for rare predicted loss-of-function (pLoF) variants, which were prioritized using ClinVar annotations, measures of gene transcriptional output and evolutionary constraint, and pLoF confidence predictions. Prevalence was reported for pLoF variant carriers based on DCM-associated gene tiers. Clinical features were compared between carriers and non-carriers. Of the 1412 HFrEF participants with whole-exome sequence data, 68 (4.8%) had at least one pLoF variant in the 8 tier-1 genes (definitive/strong association with DCM), with Titin being most commonly affected. The prevalence increased to 7.5% when considering all 44 genes. Among patients with idiopathic aetiology, 10.0% (23/229) had tier-1 variants only and 12.6% (29/229) had tier-1, -2 or -3 variants. Compared to non-carriers, tier-1 carriers were younger (4 years; adjusted p-value [padj ] = 4 × 10-3 ), leaner (27.8 kg/m2 vs. 29.4 kg/m2 ; padj  = 3.2 × 10-3 ), had lower ejection fraction (27.3% vs. 29.8%; padj  = 5.8 × 10-3 ), and less likely to have ischaemic aetiology (37.3% vs. 67.4%; padj  = 4 × 10-4 ).

CONCLUSION

Deleterious pLoF variants in genes with definitive/strong association with DCM were identified in ∼5% of HFrEF patients from a PARADIGM-HF trial subset, who were younger, had lower ejection fraction and were less likely to have had an ischaemic aetiology.

Diagnostic and prognostic relevance of using large gene panels in the genetic testing of patients with dilated cardiomyopathy

It was previously suggested that increasing the number of genes on diagnostic gene panels could increase the genetic yield in patient with dilated cardiomyopathy (DCM). We explored the diagnostic and prognostic relevance of testing DCM patients with an expanded gene panel. The current study included 225 consecutive DCM patients who had no genetic diagnosis after a 48-gene cardiomyopathy-panel. These were then evaluated using an expanded gene panel of 299 cardiac-associated genes. A likely pathogenic/pathogenic (P/LP) variant was detected in 13 patients. Five variants were reclassifications of variants found in genes which were already detected using the 48 gene panel. Only one of the other eight variants could explain the phenotype of the patient (KCNJ2). The panel detected 186 VUSs in 127 patients (of which 6 also had a P/LP variant). The presence of a VUS was significantly associated with the combined end-point of mortality, heart failure hospitalization, heart transplantation or life-threatening arrhythmias(HR, 2.04 [95% CI, 1.15 to 3.65]; p = 0.02). The association of a VUS with prognosis remained when we only included VUSs in robust DCM-associated genes (high suspicious VUSs), but disappeared when we only included VUSs in non-robust DCM-associated genes (low suspicious VUSs), highlighting the importance of weighing of VUSs. Overall, the use of large gene panels for genetic testing in DCM does not increase the diagnostic yield, although a VUS in a robust DCM-associated gene is associated with an adverse prognosis. Altogether, current diagnostic gene panels should be limited to the robust DCM-associated genes.

Cardiac Inflammation in Adult-Onset Genetic Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) has a genetic cause in up to 40% of cases, with differences in disease penetrance and clinical presentation, due to different exogeneous triggers and implicated genes. Cardiac inflammation can be the consequence of an exogeneous trigger, subsequently unveiling a phenotype. The study aimed to determine cardiac inflammation in a cohort of genetic DCM patients and investigate whether it associated with a younger disease onset. The study included 113 DCM patients with a genetic etiology, of which 17 had cardiac inflammation as diagnosed in an endomyocardial biopsy. They had a significant increased cardiac infiltration of white blood, cytotoxic T, and T-helper cells (p < 0.05). Disease expression was at a younger age in those patients with cardiac inflammation, compared to those without inflammation (p = 0.015; 50 years (interquartile range (IQR) 42-53) versus 53 years (IQR 46-61). However, cardiac inflammation was not associated with a higher incidence of all-cause mortality, heart failure hospitalization, or life-threatening arrhythmias (hazard ratio 0.85 [0.35-2.07], p = 0.74). Cardiac inflammation is associated with an earlier disease onset in patients with genetic DCM. This might indicate that myocarditis is an exogeneous trigger unveiling a phenotype at a younger age in patients with a genetic susceptibility, or that cardiac inflammation resembles a 'hot-phase' of early-onset disease.

Genetically determined cardiomyopathies at autopsy: the pivotal role of the pathologist in establishing the diagnosis and guiding family screening

Cardiomyopathies (CMP) comprise a heterogenous group of diseases affecting primarily the myocardium, either genetic and/or acquired in origin. While many classification systems have been proposed in the clinical setting, there is no internationally agreed pathological consensus concerning the diagnostic approach to inherited CMP at autopsy. A document on autopsy diagnosis of CMP is needed because the complexity of the pathologic backgrounds requires proper insight and expertise. In cases presenting with cardiac hypertrophy and/or dilatation/scarring with normal coronary arteries, a suspicion of inherited CMP must be considered, and a histological examination is essential. Establishing the actual cause of the disease may require a number of tissue-based and/or fluid-based investigations, be it histological, ultrastructural, or molecular. A history of illicit drug use must be looked for. Sudden death is frequently the first manifestation of disease in case of CMP, especially in the young. Also, during routine clinical or forensic autopsies, a suspicion of CMP may arise based on clinical data or pathological findings at autopsy. It is thus a challenge to make a diagnosis of a CMP at autopsy. The pathology report should provide the relevant data and a cardiac diagnosis which can help the family in furthering investigations, including genetic testing in case of genetic forms of CMP. With the explosion in molecular testing and the concept of the molecular autopsy, the pathologist should use strict criteria in the diagnosis of CMP, and helpful for clinical geneticists and cardiologists who advise the family as to the possibility of a genetic disease.

An intervention strategy to improve genetic testing for dilated cardiomyopathy in a heart failure clinic

PURPOSE

Despite its clinical implications in screening and therapy, genetic testing in dilated cardiomyopathy (DCM) is underused. This study evaluated implementing a practice intervention in a heart failure clinic to automate and streamline the process of genetic testing.

METHODS

Eligible patients with DCM were compared for frequency of pretest genetic education and testing during pre- and postintervention periods. The intervention comprised automated prescheduling of a cardiovascular genomics e-consult that served as a placeholder for downstream, pretest education, testing, and post-test review of genetic results.

RESULTS

Patients with DCM were more likely to undergo pretest genetic education after intervention than before intervention (33.5% vs 14.8%, P < .0001). Similarly, patients with DCM were more likely to undergo genetic testing after intervention than before intervention (27.3% vs 13.0%, P = .0006). The number of patients who were diagnosed to have likely pathogenic or pathogenic genetic variants were 2 of 21 (9.5%) and 6 of 53 (11.1%) before and after intervention, respectively, and variants were present in the following genes: FLNC, TTN, DES, LMNA, PLN, and TNNT2.

CONCLUSION

An intervention strategy in a heart failure clinic to increase the rates of pretest genetic education and testing in eligible patients with DCM was feasible and efficacious and may have important implications for the management of DCM.

A Crossroads Junction That Leads to Heart Failure (Arrhythmogenic Cardiomyopathy): Hope for Future Therapeutics

Arrhythmogenic cardiomyopathy (ACM) is an inherited multifaceted cardiac disease that causes sudden cardiac death, especially in young adults and athletes [...]

Clustering of Cardiac Transcriptome Profiles Reveals Unique

Dilated cardiomyopathy is a heterogeneous disease characterized by multiple genetic and environmental etiologies. The majority of patients are treated the same despite these differences. The cardiac transcriptome provides information on the patient's pathophysiology, which allows targeted therapy. Using clustering techniques on data from the genotype, phenotype, and cardiac transcriptome of patients with early- and end-stage dilated cardiomyopathy, more homogeneous patient subgroups are identified based on shared underlying pathophysiology. Distinct patient subgroups are identified based on differences in protein quality control, cardiac metabolism, cardiomyocyte function, and inflammatory pathways. The identified pathways have the potential to guide future treatment and individualize patient care.

Dilated cardiomyopathy and chronic cardiac inflammation: Pathogenesis, diagnosis and therapy

Dilated cardiomyopathy (DCM) is typically defined by left ventricular dilation and systolic dysfunction in the absence of a clear precipitant. Idiopathic disease is common; up to 50% of patients with DCM have no cause found despite imaging, genetic and biopsy assessments. Treatment remains focused on managing symptoms, reducing the risk of sudden cardiac death and ameliorating the structural and electrical complications of disease progression. In the absence of aetiology-specific treatments, the condition remains associated with a poor prognosis; mortality is approximately 40% at 10 years. The role of immune-mediated inflammatory injury in the development and progression of DCM was first proposed over 30 years ago. Despite the subsequent failures of three large clinical trials of immunosuppressive treatment (ATTACH, RENEWAL and the Myocarditis Treatment Trial), evidence for an abnormal adaptive immune response in DCM remains significant. In this review, we summarise and discuss available evidence supporting immune dysfunction in DCM, with a specific focus on cellular immunity. We also highlight current clinical and experimental treatments. We propose that the success of future immunosuppressive treatment trials in DCM will be dependent on the deep immunophenotyping of patients, to identify those with active inflammation and/or an abnormal immune response who are most likely to respond to therapy.

Mutation update for the ACTN2 gene

ACTN2 encodes alpha-actinin-2, a protein expressed in human cardiac and skeletal muscle. The protein, located in the sarcomere Z-disk, functions as a link between the anti-parallel actin filaments. This important structural protein also binds N-terminal titins, and thus contributes to sarcomere stability. Previously, ACTN2 mutations have been solely associated with cardiomyopathy, without skeletal muscle disease. Recently, however, ACTN2 mutations have been associated with novel congenital and distal myopathy. Previously reported variants are in varying locations across the gene, but the potential clustering effect of pathogenic locations is not clearly understood. Further, the genotype-phenotype correlations of these variants remain unclear. Here we review the previously reported ACTN2-related molecular and clinical findings and present an additional variant, c.1840-2A>T, that further expands the mutation and phenotypic spectrum. Our results show a growing body of clinical, genetic, and functional evidence, which underlines the central role of ACTN2 in the muscle tissue and myopathy. However, limited segregation and functional data are available to support the pathogenicity of most previously reported missense variants and clear-cut genotype-phenotype correlations are currently only demonstrated for some ACTN2-related myopathies.

KLF13 Loss‐of‐Function Mutations Underlying Familial Dilated Cardiomyopathy

Background

Dilated cardiomyopathy (DCM), characterized by progressive left ventricular enlargement and systolic dysfunction, is the most common type of cardiomyopathy and a leading cause of heart failure and cardiac death. Accumulating evidence underscores the critical role of genetic defects in the pathogenesis of DCM, and >250 genes have been implicated in DCM to date. However, DCM is of substantial genetic heterogeneity, and the genetic basis underpinning DCM remains elusive in most cases.

Methods and Results

By genome‐wide scan with microsatellite markers and genetic linkage analysis in a 4‐generation family inflicted with autosomal‐dominant DCM, a new locus for DCM was mapped on chromosome 15q13.1–q13.3, a 4.77‐cM (≈3.43 Mbp) interval between markers D15S1019 and D15S1010, with the largest 2‐point logarithm of odds score of 5.1175 for the marker D15S165 at recombination fraction (θ)=0.00. Whole‐exome sequencing analyses revealed that within the mapping chromosomal region, only the mutation in the KLF13 gene, c.430G>T (p.E144X), cosegregated with DCM in the family. In addition, sequencing analyses of KLF13 in another cohort of 266 unrelated patients with DCM and their available family members unveiled 2 new mutations, c.580G>T (p.E194X) and c.595T>C (p.C199R), which cosegregated with DCM in 2 families, respectively. The 3 mutations were absent from 418 healthy subjects. Functional assays demonstrated that the 3 mutants had no transactivation on the target genes ACTC1 and MYH7 (2 genes causally linked to DCM), alone or together with GATA4 (another gene contributing to DCM), and a diminished ability to bind the promoters of ACTC1 and MYH7 . Add, the E144X‐mutant KLF13 showed a defect in intracellular distribution.

Conclusions

This investigation indicates KLF13 as a new gene predisposing to DCM, which adds novel insight to the molecular pathogenesis underlying DCM, implying potential implications for prenatal prevention and precision treatment of DCM in a subset of patients.

Genetic Testing as a Guide for Treatment in Dilated Cardiomyopathies

PURPOSE OF REVIEW

Dilated cardiomyopathy (DCM) is one of the most prevalent primary cardiomyopathies and may be caused by genetic and non-genetic etiologies. DCM may also be the final common pathway of other cardiomyopathies such as hypertrophic, arrhythmogenic, or non-compaction cardiomyopathy. We review the main DCM genetic substrates, specific genotype-phenotype aspects, the role of genetic testing in risk stratification, and advances regarding genotype-based precision medicine.

RECENT FINDINGS

Performing a comprehensive genetic study could have a diagnostic yield up to 40% in DCM, and it is considered a cost-effective approach nowadays. The detection of a specific underlying genetic substrate explaining the disease can have important consequences for clinical management, especially for familial cascade screening, optimizing medical treatment, and improving the arrhythmic risk stratification. The identification of the genetic substrate underlying dilated cardiomyopathy makes possible the genotype-phenotype correlation analysis and a better understanding of the natural history of this disease. Nowadays, there are many promising targeting-gene therapies in different developing phases.

Natural History of MYH7-Related Dilated Cardiomyopathy

BACKGROUND

Variants in myosin heavy chain 7 (MYH7) are responsible for disease in 1% to 5% of patients with dilated cardiomyopathy (DCM); however, the clinical characteristics and natural history of MYH7-related DCM are poorly described.

OBJECTIVES

We sought to determine the phenotype and prognosis of MYH7-related DCM. We also evaluated the influence of variant location on phenotypic expression.

METHODS

We studied clinical data from 147 individuals with DCM-causing MYH7 variants (47.6% female; 35.6 ± 19.2 years) recruited from 29 international centers.

RESULTS

At initial evaluation, 106 (72.1%) patients had DCM (left ventricular ejection fraction: 34.5% ± 11.7%). Median follow-up was 4.5 years (IQR: 1.7-8.0 years), and 23.7% of carriers who were initially phenotype-negative developed DCM. Phenotypic expression by 40 and 60 years was 46% and 88%, respectively, with 18 patients (16%) first diagnosed at <18 years of age. Thirty-six percent of patients with DCM met imaging criteria for LV noncompaction. During follow-up, 28% showed left ventricular reverse remodeling. Incidence of adverse cardiac events among patients with DCM at 5 years was 11.6%, with 5 (4.6%) deaths caused by end-stage heart failure (ESHF) and 5 patients (4.6%) requiring heart transplantation. The major ventricular arrhythmia rate was low (1.0% and 2.1% at 5 years in patients with DCM and in those with LVEF of ≤35%, respectively). ESHF and major ventricular arrhythmia were significantly lower compared with LMNA-related DCM and similar to DCM caused by TTN truncating variants.

CONCLUSIONS

MYH7-related DCM is characterized by early age of onset, high phenotypic expression, low left ventricular reverse remodeling, and frequent progression to ESHF. Heart failure complications predominate over ventricular arrhythmias, which are rare.

Genomic findings of hypertrophic and dilated cardiomyopathy characterized in a Thai clinical genetics service

Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are the most common referrals in the Inherited Cardiovascular Condition (ICC) Genetics Service. Several issues must be discussed with patients and their families during the genetic consultation session, including the options for genetic testing and cardiovascular surveillance in family members. We developed an ICC registry and performed next-generation-based DNA sequencing for all patients affected by non-syndromic HCM and idiopathic DCM in our joint specialist genetics service. The target gene sequencing panel relied on the Human Phenotype Ontology with 237 genes for HCM (HP:0001639) and 142 genes for DCM (HP:0001644). All subjects were asked to contact their asymptomatic first-degree relatives for genetic counseling regarding their risks and to initiate cardiovascular surveillance and cascade genetic testing. The study was performed from January 1, 2014, to December 31, 2020, and a total of 62 subjects (31-HCM and 31-DCM) were enrolled. The molecular detection frequency was 48.39% (32.26% pathogenic/likely pathogenic, 16.13% variant of uncertain significance or VUS for HCM, and 25.81% (16.13% pathogenic/likely pathogenic, 9.68% VUS) for DCM. The most prevalent gene associated with HCM was MYBPC3. The others identified in this study included ACTN2, MYL2, MYH7, TNNI3, TPM1, and VCL. Among the DCM subjects, variants were detected in two cases with the TTN nonsense variants, while the others were missense and identified in MYH7, DRSP3, MYBPC3, and SCN5A. Following the echocardiogram surveillance and cascade genetic testing in the asymptomatic first-degree relatives, the detection rate of new cases was 8.82% and 6.25% in relatives of HCM and DCM subjects, respectively. Additionally, a new pre-symptomatic relative belonging to an HCM family was identified, although the genomic finding in the affected case was absent. Thus, ICC service is promising for the national healthcare system, aiming to prevent morbidity and mortality in asymptomatic family members.

Clinical Risk Score to Predict Pathogenic Genotypes in Patients With Dilated Cardiomyopathy

BACKGROUND

Although genotyping allows family screening and influences risk-stratification in patients with nonischemic dilated cardiomyopathy (DCM) or isolated left ventricular systolic dysfunction (LVSD), its result is negative in a significant number of patients, limiting its widespread adoption.

OBJECTIVES

This study sought to develop and externally validate a score that predicts the probability for a positive genetic test result (G+) in DCM/LVSD.

METHODS

Clinical, electrocardiogram, and echocardiographic variables were collected in 1,015 genotyped patients from Spain with DCM/LVSD. Multivariable logistic regression analysis was used to identify variables independently predicting G+, which were summed to create the Madrid Genotype Score. The external validation sample comprised 1,097 genotyped patients from the Maastricht and Trieste registries.

RESULTS

A G+ result was found in 377 (37%) and 289 (26%) patients from the derivation and validation cohorts, respectively. Independent predictors of a G+ result in the derivation cohort were: family history of DCM (OR: 2.29; 95% CI: 1.73-3.04; P < 0.001), low electrocardiogram voltage in peripheral leads (OR: 3.61; 95% CI: 2.38-5.49; P < 0.001), skeletal myopathy (OR: 3.42; 95% CI: 1.60-7.31; P = 0.001), absence of hypertension (OR: 2.28; 95% CI: 1.67-3.13; P < 0.001), and absence of left bundle branch block (OR: 3.58; 95% CI: 2.57-5.01; P < 0.001). A score containing these factors predicted a G+ result, ranging from 3% when all predictors were absent to 79% when ≥4 predictors were present. Internal validation provided a C-statistic of 0.74 (95% CI: 0.71-0.77) and a calibration slope of 0.94 (95% CI: 0.80-1.10). The C-statistic in the external validation cohort was 0.74 (95% CI: 0.71-0.78).

CONCLUSIONS

The Madrid Genotype Score is an accurate tool to predict a G+ result in DCM/LVSD.

Emerging Genotype-Phenotype Associations in Dilated Cardiomyopathy

PURPOSE OF REVIEW

The disease burden of inherited dilated cardiomyopathy (DCM) is large and likely underestimated. This population stands to benefit immensely from therapeutic approaches tailored to the underlying genetic causes. Here, we review recent advances in understanding novel genotype-phenotype relationships and how these can improve the care of patients with inherited DCM.

RECENT FINDINGS

In the last several years, discovery of novel DCM-associated genes, gene-specific DCM outcomes, and nuanced information about variant-environment interactions have advanced our understanding of inherited DCM. Specifically, novel associations of genes with specific clinical phenotypes can help to assess sudden cardiac death risk and guide counseling around behavioral and environmental exposures that may worsen disease. Important expansions of the current genotype-phenotype profiling include the newly DCM-associated FLNC variant, prognostically significant LMNA, DSP inflammatory cardiomyopathy, and the highly penetrant features of RBM20 variants as well as the role of TTN variants in compounding the effects of environmental factors on toxin-mediated DCM. Future directions to improve diagnostic accuracy and prognostic improvement in DCM will center not just on identification of new genes, but also on understanding the interaction of known and novel variants in known DCM genes with patient genetic background and environment.

Interatrial Block Predicts Life-Threatening Arrhythmias in Dilated Cardiomyopathy

Background Interatrial block (IAB) has been associated with supraventricular arrhythmias and stroke, and even with sudden cardiac death in the general population. Whether IAB is associated with life-threatening arrhythmias (LTA) and sudden cardiac death in dilated cardiomyopathy (DCM) remains unknown. This study aimed to determine the association between IAB and LTA in ambulant patients with DCM. Methods and Results A derivation cohort (Maastricht Dilated Cardiomyopathy Registry; N=469) and an external validation cohort (Utrecht Cardiomyopathy Cohort; N=321) were used for this study. The presence of IAB (P-wave duration>120 milliseconds) or atrial fibrillation (AF) was determined using digital calipers by physicians blinded to the study data. In the derivation cohort, IAB and AF were present in 291 (62%) and 70 (15%) patients with DCM, respectively. LTA (defined as sudden cardiac death, justified shock from implantable cardioverter-defibrillator or anti-tachypacing, or hemodynamic unstable ventricular fibrillation/tachycardia) occurred in 49 patients (3 with no IAB, 35 with IAB, and 11 patients with AF, respectively; median follow-up, 4.4 years [2.1; 7.4]). The LTA-free survival distribution significantly differed between IAB or AF versus no IAB (both P<0.01), but not between IAB versus AF (P=0.999). This association remained statistically significant in the multivariable model (IAB: HR, 4.8 (1.4-16.1), P=0.013; AF: HR, 6.4 (1.7-24.0), P=0.007). In the external validation cohort, the survival distribution was also significantly worse for IAB or AF versus no IAB (P=0.037; P=0.005), but not for IAB versus AF (P=0.836). Conclusions IAB is an easy to assess, widely applicable marker associated with LTA in DCM. IAB and AF seem to confer similar risk of LTA. Further research on IAB in DCM, and on the management of IAB in DCM is warranted.

A Comprehensive Outlook on Dilated Cardiomyopathy (DCM): State-Of-The-Art Developments with Special Emphasis on OMICS-Based Approaches

Dilated cardiomyopathy (DCM) remains an enigmatic cardiovascular disease (CVD) condition characterized by contractile dysfunction of the myocardium due to dilation of the ventricles. DCM is one of the major forms of CVD contributing to heart failure. Dilation of the left or both ventricles with systolic dysfunction, not explained by known causes, is a hallmark of DCM. Progression of DCM leads to heart failure. Genetic and various other factors greatly contribute to the development of DCM, but the etiology has still remained elusive in a large number of cases. A significant number of studies have been carried out to identify the genetic causes of DCM. These candidate-gene studies revealed that mutations in the genes of the fibrous, cytoskeletal, and sarcomeric proteins of cardiomyocytes result in the development of DCM. However, a significant proportion of DCM patients are idiopathic in nature. In this review, we holistically described the symptoms, causes (in adults and newborns), genetic basis, and mechanistic progression of DCM. Further, we also summarized the state-of-the-art diagnosis, available biomarkers, treatments, and ongoing clinical trials of potential drug regimens. DCM-mediated heart failure is on the rise worldwide including in India. The discovery of biomarkers with a better prognostic value is the need of the hour for better management of DCM-mediated heart failure patients. With the advent of next-generation omics-based technologies, it is now possible to probe systems-level alterations in DCM patients pertaining to the identification of novel proteomic and lipidomic biomarkers. Here, we also highlight the onset of a systems-level study in Indian DCM patients by applying state-of-the-art mass-spectrometry-based “clinical proteomics” and “clinical lipidomics”.

Evaluation of the Interaction of Sex Hormones and Cardiovascular Function and Health

Purpose of Review

Sex hormones drive development and function of reproductive organs or the development of secondary sex characteristics but their effects on the cardiovascular system are poorly understood. In this review, we identify the gaps in our understanding of the interaction between sex hormones and the cardiovascular system.

Recent Findings

Studies are progressively elucidating molecular functions of sex hormones in specific cell types in parallel with the initiation of crucial large randomized controlled trials aimed at improving therapies for cardiovascular diseases (CVDs) associated with aberrant levels of sex hormones.

Summary

In contrast with historical assumptions, we now understand that men and women show different symptoms and progression of CVDs. Abnormal levels of sex hormones pose an independent risk for CVD, which is apparent in conditions like Klinefelter syndrome, androgen insensitivity syndrome, and menopause. Moreover, sex hormone–based therapies remain understudied and may not be beneficial for cardiovascular health.

Arrhythmias as Presentation of Genetic Cardiomyopathy

There is increasing evidence regarding the prevalence of genetic cardiomyopathies, for which arrhythmias may be the first presentation. Ventricular and atrial arrhythmias presenting in the absence of known myocardial disease are often labelled as idiopathic, or lone. While ventricular arrhythmias are well-recognized as presentation for arrhythmogenic cardiomyopathy in the right ventricle, the scope of arrhythmogenic cardiomyopathy has broadened to include those with dominant left ventricular involvement, usually with a phenotype of dilated cardiomyopathy. In addition, careful evaluation for genetic cardiomyopathy is also warranted for patients presenting with frequent premature ventricular contractions, conduction system disease, and early onset atrial fibrillation, in which most detected genes are in the cardiomyopathy panels. Sudden death can occur early in the course of these genetic cardiomyopathies, for which risk is not adequately tracked by left ventricular ejection fraction. Only a few of the cardiomyopathy genotypes implicated in early sudden death are recognized in current indications for implantable cardioverter defibrillators which otherwise rely upon a left ventricular ejection fraction ≤0.35 in dilated cardiomyopathy. The genetic diagnoses impact other aspects of clinical management such as exercise prescription and pharmacological therapy of arrhythmias, and new therapies are coming into clinical investigation for specific genetic cardiomyopathies. The expansion of available genetic information and implications raises new challenges for genetic counseling, particularly with the family member who has no evidence of a cardiomyopathy phenotype and may face a potentially negative impact of a genetic diagnosis. Discussions of risk for both probands and relatives need to be tailored to their numeric literacy during shared decision-making. For patients presenting with arrhythmias or cardiomyopathy, extension of genetic testing and its implications will enable cascade screening, intervention to change the trajectory for specific genotype-phenotype profiles, and enable further development and evaluation of emerging targeted therapies.

Combination of late gadolinium enhancement and genotype improves prediction of prognosis in non-ischemic dilated cardiomyopathy

Aims

Genotype and left ventricular scar on cardiac magnetic resonance (CMR) are increasingly recognized as risk markers for adverse outcomes in non‐ischaemic dilated cardiomyopathy (DCM). We investigated the combined influence of genotype and late gadolinium enhancement (LGE) in assessing prognosis in a large cohort of patients with DCM.

Methods and results

Outcomes of 600 patients with DCM (53.3 ± 14.1 years, 66% male) who underwent clinical CMR and genetic testing were retrospectively analysed. The primary endpoints were end‐stage heart failure (ESHF) and malignant ventricular arrhythmias (MVA). During a median follow‐up of 2.7 years (interquartile range 1.3–4.9), 24 (4.00%) and 48 (8.00%) patients had ESHF and MVA, respectively. In total, 242 (40.3%) patients had pathogenic/likely pathogenic variants (positive genotype) and 151 (25.2%) had LGE. In survival analysis, positive LGE was associated with MVA and ESHF (both, p < 0.001) while positive genotype was associated with ESHF (p = 0.034) but not with MVA (p = 0.102). Classification of patients according to genotype (G+/G−) and LGE presence (L+/L−) revealed progressively increasing events across L−/G−, L−/G+, L+/G− and L+/G+ groups and resulted in optimized MVA and ESHF prediction (p < 0.001 and p = 0.001, respectively). Hazard ratios for MVA and ESHF in patients with either L+ or G+ compared with those with L−/G− were 4.71 (95% confidence interval: 2.11–10.50, p < 0.001) and 7.92 (95% confidence interval: 1.86–33.78, p < 0.001), respectively.

Conclusion

Classification of patients with DCM according to genotype and LGE improves MVA and ESHF prediction. Scar assessment with CMR and genotyping should be considered to select patients for primary prevention implantable cardioverter‐defibrillator placement.

Recent Non-Invasive Parameters to Identify Subjects at High Risk of Sudden Cardiac Death

Cardiovascular diseases remain among the leading causes of death worldwide and sudden cardiac death (SCD) accounts for ~25% of these deaths. Despite its epidemiologic relevance, there are very few diagnostic strategies available useful to prevent SCD mainly focused on patients already affected by specific cardiovascular diseases. Unfortunately, most of these parameters exhibit poor positive predictive accuracy. Moreover, there is also a need to identify parameters to stratify the risk of SCD among otherwise healthy subjects. This review aims to provide an update on the most relevant non-invasive diagnostic features to identify patients at higher risk of developing malignant ventricular arrhythmias and SCD.

Genetically Based Atrial Fibrillation: Current Considerations for Diagnosis and Management

Atrial fibrillation (AF) is the most common atrial arrhythmia and is subcategorized into numerous clinical phenotypes. Given its heterogeneity, investigations into the genetic mechanisms underlying AF have been pursued in recent decades, with predominant analyses focusing on early onset or lone AF. Linkage analyses, genome wide association studies (GWAS), and single gene analyses have led to the identification of rare and common genetic variants associated with AF risk. Significant overlap with genetic variants implicated in dilated cardiomyopathy syndromes, including truncating variants of the sarcomere protein titin, have been identified through these analyses, in addition to other genes associated with cardiac structure and function. Despite this, widespread utilization of genetic testing in AF remains hindered by the unclear impact of genetic risk identification on clinical outcomes and the high prevalence of variants of unknown significance (VUS). However, genetic testing is a reasonable option for patients with early onset AF and in those with significant family history of arrhythmia. While many knowledge gaps remain, emerging data support genotyping to inform selection of AF therapeutics. In this review we highlight the current understanding of the complex genetic basis of AF and explore the overlap of AF with inherited cardiomyopathy syndromes. We propose a set of criteria for clinical genetic testing in AF patients and outline future steps for the integration of genetics into AF care. This article is protected by copyright. All rights reserved.

Rare Genetic Variants Associated With Myocardial Fibrosis: Multi-Ethnic Study of Atherosclerosis

Background

Rare pathogenic variants in cardiomyopathy (CM) genes can predispose to cardiac remodeling or fibrosis. We studied the carrier status for such variants in adults without clinical cardiovascular disease (CVD) in whom cardiac MRI (CMR)-derived measures of myocardial fibrosis were obtained in the Multi-Ethnic Study of Atherosclerosis (MESA).

Objectives

To identify CM-associated pathogenic variants and assess their relative prevalence in participants with extensive myocardial fibrosis by CMR.

Methods

MESA whole-genome sequencing data was evaluated to capture variants in CM-associated genes (n = 82). Coding variants with a frequency of <0.1% in gnomAD and 1,000 Genomes Project databases and damaging/deleterious effects based on in-silico scoring tools were assessed by ClinVar database and ACMG curation guidelines for evidence of pathogenicity. Cases were participants with high myocardial fibrosis defined as highest quartile of extracellular volume (ECV) or native T1 time in T1-mapping CMR and controls were the remainder of participants.

Results

A total of 1,135 MESA participants had available genetic data and phenotypic measures and were free of clinical CVD at the time of CMR. We identified 6,349 rare variants in CM-associated genes in the overall MESA population, of which six pathogenic/likely pathogenic (P/LP) variants were present in the phenotyped subpopulation. The genes harboring P/LP variants in the case group were MYH7, CRYAB, and SCN5A. The prevalence of P/LP rare variants in cases was higher than controls (5 in 420 [1.1%] vs. 1 in 715 [0.1%], p = 0.03). We identified two MYBPC3 Variants of Unknown Significance (VUS)s with borderline pathogenicity in the case group. The left ventricle (LV) volume, mass, ejection fraction (EF), and longitudinal and circumferential strain in participants with the variants were not different compared to the overall cohort.

Conclusions

We observed a higher prevalence of rare potentially pathogenic CM associated genetic variants in participants with significant myocardial fibrosis quantified in CMR as compared to controls without significant fibrosis. No cardiac structural or functional differences were found between participants with or without P/LP variants.

Clinical impact of re-evaluating genes and variants implicated in dilated cardiomyopathy

PURPOSE

Accurate interpretation of variants detected in dilated cardiomyopathy (DCM) is crucial for patient care but has proven challenging. We applied a set of proposed refined American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) criteria for DCM, reclassified all detected variants in robust genes, and associated these results to patients' phenotype.

METHODS

The study included 902 DCM probands from the Maastricht Cardiomyopathy Registry who underwent genetic testing. Two gene panel sizes (extended n = 48; and robust panel n = 14) and two standards of variant classification (standard versus the proposed refined ACMG/AMP criteria) were applied to compare genetic yield.

RESULTS

A pathogenic or likely pathogenic (P/LP) variant was found in 17.8% of patients, and a variant of uncertain significance (VUS) was found in 32.8% of patients when using method 1 (extended panel (n = 48) + standard ACMG/AMP), compared to respectively 16.9% and 12.9% when using method 2 (robust panel (n = 14) + standard ACMG/AMP), and respectively 14% and 14.5% using method 3 (robust panel (n = 14) + refined ACMG/AMP). Patients with P/LP variants had significantly lower event-free survival compared to genotype-negative DCM patients.

CONCLUSION

Stringent gene selection for DCM genetic testing reduced the number of VUS while retaining ability to detect similar P/LP variants. The number of genes on diagnostic panels should be limited to genes that have the highest signal to noise ratio.

Association of Genetic Variants With Outcomes in Patients With Nonischemic Dilated Cardiomyopathy

BACKGROUND

The clinical relevance of genetic variants in nonischemic dilated cardiomyopathy (DCM) is unsettled.

OBJECTIVES

The study sought to assess the prognostic impact of disease-causing genetic variants in DCM.

METHODS

Baseline and longitudinal clinical data from 1,005 genotyped DCM probands were retrospectively collected at 20 centers. A total of 372 (37%) patients had pathogenic or likely pathogenic variants (genotype positive) and 633 (63%) were genotype negative. The primary endpoint was a composite of major adverse cardiovascular events. Secondary endpoints were end-stage heart failure (ESHF), malignant ventricular arrhythmia (MVA), and left ventricular reverse remodeling (LVRR).

RESULTS

After a median follow-up of 4.04 years (interquartile range: 1.70-7.50 years), the primary endpoint had occurred in 118 (31.7%) patients in the genotype-positive group and in 125 (19.8%) patients in the genotype-negative group (hazard ratio [HR]: 1.51; 95% confidence interval [CI]: 1.17-1.94; P = 0.001). ESHF occurred in 60 (16.1%) genotype-positive patients and in 55 (8.7%) genotype-negative patients (HR: 1.67; 95% CI: 1.16-2.41; P = 0.006). MVA occurred in 73 (19.6%) genotype-positive patients and in 77 (12.2%) genotype-negative patients (HR: 1.50; 95% CI: 1.09-2.07; P = 0.013). LVRR occurred in 39.6% in the genotype-positive group and in 46.2% in the genotype-negative group (P = 0.047). Among individuals with baseline left ventricular ejection fraction ≤35%, genotype-positive patients exhibited more major adverse cardiovascular events, ESHF, and MVA than their genotype-negative peers (all P < 0.02). LVRR and clinical outcomes varied depending on the underlying affected gene.

CONCLUSIONS

In this study, DCM patients with pathogenic or likely pathogenic variants had worse prognosis than genotype-negative individuals. Clinical course differed depending on the underlying affected gene.