Prognostic Prediction of Genotype vs Phenotype in Genetic Cardiomyopathies

Cardiomyopathy genetic testing: insights into demographics, counseling, and cascade screening

BACKGROUND

Genetic testing (GT) is clinically indicated for patients with suspected inherited cardiomyopathy (CM) but is underutilized.

METHODS

This single-center study included patients with CM who underwent outpatient GT from 2018 to 2023. Data were collected from the medical record.

RESULTS

A total of 306 patients were included, with a mean age of 62 years and were predominantly male (63%) and White (59%). Heart failure (92%) cardiologists were most likely to order testing, followed by general cardiology (5%) providers at tertiary hospital clinics (89%). The most common phenotypes were hypertrophic (30%), amyloid (29%) and dilated (21%). There were 17% of patients who had a positive test and 53% of patients who had a variant of uncertain significance. Patients with a positive family history had a significantly higher positive yield compared to those without (p < 0.01). Genetic counselors were underutilized (17%). For patients who had a positive test result, only 40% had cascade screening.

CONCLUSIONS

Outpatient GT for CM was primarily ordered by heart failure cardiologists in tertiary hospital clinics. Cascade screening was low, which may reflect the limited use of genetic counselors. Further research is needed to understand implementation barriers to GT.

Prediction and prognostic role of left ventricular systolic dysfunction in family screening for dilated cardiomyopathy and non-dilated left ventricular cardiomyopathy

AIMS

The prognostic significance of detecting left ventricular (LV) systolic dysfunction during family screening programmes (FSPs) in relatives of probands affected by dilated (DCM) and non-dilated left ventricular (NDLVC) cardiomyopathies remain unclear. This study sought to evaluate the prognostic role of LV systolic dysfunction detection in relatives of DCM/NDLVC probands and to define the most accurate FSP.

METHODS AND RESULTS

Baseline and follow-up data of first-degree relatives of probands affected by DCM/NDLVC were collected. The primary outcome was all-cause death and heart transplantation. Secondary heart failure (HF) and arrhythmic outcomes were also included. A total of 492 first degree relatives were enrolled. During a median follow-up of 110 months (interquartile range 57-188 months), only subjects that previously developed LV systolic dysfunction had primary outcomes (19 vs. 0, p < 0.001) and secondary outcomes (HF: 12 vs. 0, p = 0.005; arrhythmic: 30 vs. 0, p < 0.001). Subjects with LV systolic dysfunction detected by FSP showed lower rate of primary outcomes (FSP: n = 19 [14%]; no-FSP: n = 40 [37%]; p < 0.001) and secondary arrhythmic outcomes (FSP: n = 18 [13%]; no-FSP: n = 41 [38%]; p < 0.001). In this setting, family history of arrhythmia and being carrier of a pathogenic/likely pathogenic variant are the main risk factors for LV systolic dysfunction, while LV global longitudinal strain (LV-GLS) and Holter electrocardiogram (ECG) showed a relevant role in terms of prediction of LV systolic dysfunction and outcomes.

CONCLUSION

Relatives of DCM/NDLVC probands who developed LV systolic dysfunction during a long follow-up had a significant increased risk of major adverse cardiovascular outcomes. However, LV systolic dysfunction detected by FSP showed a better prognosis. In this context, genetics, Holter ECG and LV-GLS demonstrated their functional role for disease and event prediction.

Arrhythmic risk prediction in non-dilated left ventricular cardiomyopathy: The role of overlap with arrhythmogenic cardiomyopathy

BACKGROUND

Non-dilated left ventricular cardiomyopathy (NDLVC) has been defined as non-ischemic LV scarring or fatty replacement regardless of global or regional wall motion abnormalities, or isolated global LV hypokinesia without scarring. We evaluated the arrhythmic risk in NDLVC and assessed the prognostic value of overlapping features with arrhythmogenic cardiomyopathy (ACM).

METHODS

All patients who underwent cardiovascular magnetic resonance (CMR) scan and genetic testing between 2012 and 2022 and met the diagnostic criteria for NDLVC were selected. All patients were evaluated for the presence of the 2024 diagnostic criteria for ACM. The primary endpoint was a composite of sudden cardiac death (SCD), ventricular fibrillation (VF) or sustained ventricular tachycardia (VT),.

RESULTS

The cohort included 225 patients (35 % women, median age 55 years [interquartile range 44-64]). The etiology was genetic in 44 % of cases, with 51 pathogenetic/likely pathogenetic (P/LP) variant and 49 variant of uncertain significance (VUS). Over 3.3 years (1.5-6.0), 12 patients (5 %) developed an endpoint event. The risk increased in patients meeting the criteria for definite or borderline arrhythmogenic left ventricular (ALVC) and biventricular (ABVC) cardiomyopathy. In the whole cohort, LGE >9 % of LV mass was the most significant predictor of outcome. In patients with LGE >9 %, fatty replacement significantly increased the risk of arrhythmic events.

CONCLUSIONS

LGE >9 % of LV mass and fatty replacement are associated with an increased arrhythmic risk in NDLVC. The risk is also higher if patients meet the 2024 criteria for definite or borderline ALVC/ABVC.

The contribution of genetics to the understanding and management of cardiomyopathies: Part 1

Genetics has assumed a pivotal role in clarifying the pathophysiology of cardiomyopathies, facilitating molecular diagnosis, and enabling effective family screening. The advent of next-generation sequencing has revolutionized genetic testing by enabling cost-effective, high-throughput analysis. It is imperative for cardiovascular physicians to mainstream genetic testing into their clinical decision-making. Although a definitive genotype-phenotype correlation may not always be evident, several genotypes have emerged as valuable risk predictors for disease severity and progression. European guidelines emphasize the importance of genetic tests for predicting clinical outcome in cardiomyopathies. While further research is essential to bridge existing gaps in the genetic evidence on cardiomyopathies, there is considerable potential for significant advancements.

Natural History, Phenotype Spectrum, and Clinical Outcomes of Desmin (DES)-Associated Cardiomyopathy

BACKGROUND

Pathogenic/likely pathogenic (LP) desmin (DES) variants cause heterogeneous cardiomyopathy and skeletal myopathy phenotypes. Limited data suggest a high incidence of major adverse cardiac events (MACEs), including cardiac conduction disease, sustained ventricular arrhythmias (VA), and heart failure (HF) events (HF hospitalization, left ventricular assist device/cardiac transplant, HF-related death) in patients with pathogenic/LP DES variants. However, pleiotropic presentation and small cohort sizes have limited clinical phenotype and outcome characterization. We aimed to describe the natural history, phenotype spectrum, familial penetrance and outcomes in patients with pathogenic/LP DES variants through a systematic review and individual patient data meta-analysis using published reports.

METHODS

We searched Medline (PubMed) and Embase for studies that evaluated cardiac phenotypes in patients with pathogenic/LP DES variants. Cardiomyopathy diagnosis or occurrence of MACE was considered evidence of cardiac involvement/penetrance. Lifetime event-free survival from cardiac conduction disease, sustained VA, HF events, and composite MACE was assessed.

RESULTS

Of the 4212 screened publications, 71 met the inclusion criteria. A total of 230 patients were included (52.6% men, 52.2% probands, median age: 31 years [22.0-42.8] at first evaluation, median follow-up: 3 years [0-11.0]). Overall, 124 (53.9%) patients were diagnosed with cardiomyopathy, predominantly dilated cardiomyopathy (14.8%), followed by restrictive cardiomyopathy (13.5%), whereas other forms were less common: arrhythmogenic cardiomyopathy (7.0%), hypertrophic cardiomyopathy (6.1%), arrhythmogenic right ventricular cardiomyopathy (5.2%), and other forms (7.4%). Overall, 132 (57.4%) patients developed MACE, with 96 (41.7%) having cardiac conduction disease, 36 (15.7%) sustained VA, and 43 (18.7%) HF events. Familial penetrance of cardiac disease was 63.6% among relatives with pathogenic/LP DES variants. Male sex was associated with an increased risk of sustained VA (hazard ratio, 2.28; P=0.02) and HF events (hazard ratio, 2.45; P=0.008).

CONCLUSIONS

DES cardiomyopathy exhibits heterogeneous phenotypes and a distinct natural history, characterized by high familial penetrance and a substantial MACE burden. Male patients face a higher risk of sustained VA events.

Case report: Severe arrhythmogenic cardiomyopathy in a young girl with compound heterozygous DSG2 and MYBPC3 variants with a 6-year follow-up

Introduction

Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiac disorder characterized by progressive fibrofatty replacement of the myocardium. In the Japanese population, variants of the desmoglein-2 (DSG2) gene are a major cause of ACM, typically following an autosomal recessive inheritance pattern. Myosin-binding protein C (MYBPC3) variants are primarily associated with hypertrophic cardiomyopathy (HCM). Here, we report a severe pediatric case of ACM associated with compound heterozygous DSG2 and MYBPC3 variants.

Case Presentation

A 6-year-old asymptomatic girl was diagnosed with ACM based on abnormal electrocardiogram findings, including epsilon waves, and T-wave inversions in leads V1-6 and III. Echocardiography revealed right ventricular (RV) dilatation (RV outflow tract diameter/body surface area: 22.9 mm/m2) and reduced RV function (fractional area change: 18.0%). Cardiac magnetic resonance imaging confirmed RV dysfunction (ejection fraction [EF]: 9.7%) and left ventricular (LV) involvement (EF: 48.9%). Genetic testing identified compound heterozygous DSG2 variants (p.Arg119* and p. Arg292Cys) and an MYBPC3 variant (p.Arg820Gln). The patient remained asymptomatic until age 10.5 years, when she developed heart failure requiring hospitalization. Imaging revealed severe biventricular dilatation (LV end-diastolic volume index: 149.5 mL/m2; RV end-diastolic volume index: 255.9 mL/m2) and biventricular dysfunction (LVEF: 9.5%; RVEF: 9.7%). Despite medical management, the patient's condition progressively worsened, and she was deemed eligible for heart transplantation.

Discussion

This case illustrates the potential for severe pediatric ACM associated with compound heterozygous DSG2 variants and a MYBPC3 variant. The DSG2 variants likely played a primary role disease pathogenesis, while the MYBPC3 variant may have exacerbated the phenotype. The coexistence of desmosomal and sarcomeric gene variants is rare in cardiomyopathies, making genotype-phenotype correlations complex. Further research is needed to elucidate the interplay between these genetic factors.

Conclusion

This case underscores the genetic heterogeneity and phenotypic variability in inherited cardiomyopathies. It emphasizes the importance of comprehensive genetic testing and close monitoring of affected individuals and their families.

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.

Acute Heart Failure and Non-Ischemic Cardiomyopathies: A Comprehensive Review and Critical Appraisal

Acute heart failure (AHF) is a complex clinical syndrome characterized by the rapid or gradual onset of symptoms and/or signs of heart failure (HF), leading to an unplanned hospital admission or an emergency department visit. AHF is the leading cause of hospitalization in patients over 65 years, thus significantly impacting public health care. However, its prognosis remains poor with high rates of mortality and rehospitalization. Many pre-existing cardiac conditions can lead to AHF, but it can also arise de novo due to acute events. Therefore, understanding AHF etiology could improve patient management and outcomes. Cardiomyopathies (CMPs) are a heterogeneous group of heart muscle diseases, including dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), non-dilated cardiomyopathy (NDLVC), and arrhythmogenic right ventricular cardiomyopathy (ARVC), that frequently present with HF. Patients with CMPs are under-represented in AHF studies compared to other etiologies, and therefore therapeutic responses and prognoses remain unknown. In DCM, AHF represents the most frequent cause of death despite treatment improvements. Additionally, DCM is the first indication for heart transplant (HT) among young and middle-aged adults. In HCM, the progression to AHF is rare and more frequent in patients with concomitant severe left ventricle (LV) obstruction and hypertrophy or severe LV systolic dysfunction. HF is the natural evolution of patients with RCM and HF is associated with poor outcomes irrespective of RCM etiology. Furthermore, while the occurrence of AHF is rare among patients with ARVC, this condition in NDLVC patients is currently unknown. In this manuscript, we assessed the available evidence on AHF in patients with CMPs. Data on clinical presentation, therapeutic management, and clinical outcomes according to specific CMPs are limited. Future HF studies assessing the clinical presentation, treatment, and prognosis of specific CMPs are warranted.

Systematic Review, Meta-Analysis, and Population Study to Determine the Biologic Sex Ratio in Dilated Cardiomyopathy

BACKGROUND

Dilated cardiomyopathy (DCM) appears to be diagnosed twice as often in male than in female patients. This could be attributed to underdiagnosis in female patients or sex differences in susceptibility. Up to 30% of cases have an autosomal dominant monogenic cause, where equal sex prevalence would be expected. The aim of this systematic review, meta-analysis, and population study was to assess the sex ratio in patients with DCM, stratified by genetic status, and evaluate whether this is influenced by diagnostic bias.

METHODS

A literature search identified DCM patient cohorts with discernible sex ratios. Exclusion criteria were studies with a small (n<100), pediatric, or peripartum population. Meta-analysis and metaregression compared the proportion of female participants for an overall DCM cohort and the following subtypes: all genetic DCM, individual selected DCM genes (TTN and LMNA), and gene-elusive DCM. Population DCM sex ratios generated from diagnostic codes were also compared with those from sex-specific means using the UK Biobank imaging cohort; this established ICD coded, novel imaging-first, and genotype first determined sex ratios.

RESULTS

A total of 99 studies, with 37 525 participants, were included. The overall DCM cohort had a 0.30 female proportion (95% CI, 0.28-0.32), corresponding to a male:female ratio (M:F) of 2.38:1. This was similar to patients with an identified DCM variant (0.31 [95% CI, 0.26-0.36]; M:F 2.22:1; P=0.56). There was also no significant difference when compared with patients with gene-elusive DCM (0.30 [95% CI, 0.24-0.37]; M:F 2.29:1; P=0.81). Furthermore, the ratio within autosomal dominant gene variants was not significantly different for TTN (0.28 [95% CI, 0.22-0.36]; M:F 2.51:1; P=0.82) or LMNA (0.35 [95% CI, 0.27-0.44]; M:F 1.84:1; P=0.41). Overall, the sex ratio for DCM in people with disease attributed to autosomal dominant gene variants was similar to the all-cause group (0.34 [95% CI, 0.28-0.40]; M:F 1.98:1; P=0.19). In the UK Biobank (n=47 549), DCM defined by International Classification of Diseases, 10th revision, coding had 4.5:1 M:F. However, implementing sex-specific imaging-first and genotype-first diagnostic approaches changed this to 1.7:1 and 2.3:1, respectively.

CONCLUSIONS

This study demonstrates that DCM is twice as prevalent in male patients. This was partially mitigated by implementing sex-specific DCM diagnostic criteria. The persistent male excess in genotype-positive patients with an equally prevalent genetic risk suggests additional genetic or environmental drivers for sex-biased penetrance.

REGISTRATION

URL: https://www.crd.york.ac.uk/prospero; Unique identifier: CRD42023451944.

Feasibility and Role of Cardiac Magnetic Resonance in Intensive and Acute Cardiovascular Care

Cardiac magnetic resonance (CMR) is established as a key imaging modality in a wide range of cardiovascular diseases and has an emerging diagnostic and prognostic role in selected patients presenting acutely. Recent technical advancements have improved the versatility of this imaging technique, which has become quicker and more detailed in both functional and tissue characterization assessments. Information derived from this test has the potential to change clinical management, guide therapeutic decisions, and provide risk stratification. This review aims to highlight the evolving diagnostic and prognostic role of CMR in this setting, whilst also providing practical guidance on which patients can benefit the most from CMR and which information can be derived from this test that will impact clinical management.

Critical analysis of the 2023 ESC guidelines on cardiomyopathy management

The first European Society of Cardiology (ESC) guidelines on the management of cardiomyopathies (CMPs), published 1 year ago, remain highly relevant. These guidelines provide a comprehensive framework to manage the complexity of CMPs, consolidating previous approaches. All CMPs are now addressed systematically in one document. The ESC recommends a 'CMP-oriented' approach, emphasizing thorough clinical assessments and phenotype-first categorization into hypertrophic, dilated, arrhythmogenic, restrictive, and non-dilated left ventricular CMP. Despite the utility of this method, certain classifications, such as arrhythmogenic right ventricular CMP and the novel non-dilated left ventricular CMP, raise controversies. Key advances in the guidelines include the use of genetic testing and cardiac magnetic resonance imaging to refine diagnoses and inform treatment, especially for high-risk genotypes. These guidelines advocate for personalized, multidisciplinary care. Overall, they represent a significant step forward but highlight the evolving nature of CMP management as scientific understanding progresses.

Clinical features and outcomes in carriers of pathogenic desmoplakin variants

BACKGROUND AND AIMS

Pathogenic variants in the desmoplakin (DSP) gene are associated with the development of a distinct arrhythmogenic cardiomyopathy phenotype not fully captured by either dilated cardiomyopathy (DCM), non-dilated left ventricular cardiomyopathy (NDLVC), or arrhythmogenic right ventricular cardiomyopathy (ARVC). Prior studies have described baseline DSP cardiomyopathy genetic, inflammatory, and structural characteristics. However, cohort sizes have limited full clinical characterization and identification of clinical and demographic predictors of sustained ventricular arrhythmias (VAs), heart failure (HF) hospitalizations, and transplant/death. In particular, the relevance of acute myocarditis-like episodes for subsequent disease course is largely unknown.

METHODS

All patients with pathogenic/likely pathogenic (P/LP) DSP variants in the worldwide DSP-ERADOS Network (26 academic institutions across nine countries) were included. The primary outcomes were the development of sustained VA and HF hospitalizations during follow-up. Fine-Gray regressions were used to test association between clinical and instrumental parameters and the development of outcomes.

RESULTS

Eight hundred patients [40.3 ± 17.5 years, 47.5% probands, left ventricular ejection fraction (LVEF) 49.5 ± 13.9%] were included. Over 3.7 [1.4-7.1] years, 139 (17.4%, 3.9%/year) and 72 (9.0%, 1.8%/year) patients experienced sustained VA and HF episodes, respectively. A total of 32.5% of individuals did not fulfil diagnostic criteria for ARVC, DCM, or NDLVC; their VA incidence was 0.5%/year. In multivariable regression, risk features associated with the development of VA were female sex [adjusted hazard ratio (aHR) 1.547; P = .025], prior non-sustained ventricular tachycardia (aHR 1.721; P = .009), prior sustained VA (aHR 1.923; P = .006), and LVEF ≤ 50% (aHR: 1.645; P = .032), while for HF, they were the presence of T-wave inversion in 3+ electrocardiogram leads (aHR 2.036, P = .007) and LVEF ≤ 50% (aHR 3.879; P < .001). Additionally, 70 (8.8%) patients experienced a myocardial injury episode at presentation or during follow-up. These episodes were associated with an increased risk of VA and HF thereafter (HR 2.394; P < .001, and HR 5.064, P < .001, respectively).

CONCLUSIONS

Patients with P/LP DSP variants experience high rates of sustained VA and HF hospitalizations. These patients demonstrate a distinct clinical phenotype (DSP cardiomyopathy), whose most prominent risk features associated with adverse clinical outcomes are the presence of prior non-sustained ventricular tachycardia or sustained VA, T-wave inversion in 3+ leads on electrocardiogram, LVEF ≤ 50%, and myocardial injury events.

LMNA-related cardiomyopathy: From molecular pathology to cardiac gene therapy

BACKGROUND

The genetic variants of LMNA cause an array of diseases that often affect the heart. LMNA-related cardiomyopathy exhibits high-penetrance and early-onset phenotypes that lead to late-stage heart failure or lethal arrhythmia. As a subtype of dilated cardiomyopathy and arrhythmogenic cardiomyopathy, LMNA-related cardiac dysfunction is resistant to existing cardiac therapeutic strategies, leaving a major unmet clinical need in cardiomyopathy management.

AIM OF REVIEW

Here we comprehensively summarize current knowledge about the genetic basis, disease models and pathological mechanisms of LMNA-related cardiomyopathy. Recent translational studies were highlighted to indicate new therapeutic modalities such as gene supplementation, gene silencing and genome editing therapy, which offer potential opportunities to overcome the difficulties in the development of specific drugs for this disease.

KEY SCIENTIFIC CONCEPTS OF REVIEW

LMNA-related cardiomyopathy involves many diverse disease mechanisms that preclude small-molecule drugs that target only a small fraction of the mechanisms. Agreeing to this notion, the first-in-human clinical trial for this disease recently reported futility. By contrast, gene therapy offers the new hope to directly intervene LMNA variants and demonstrates a tremendous potential for breakthrough therapy for this disease. Concepts in this review are also applicable to studies of other genetic diseases that lack effective therapeutics.

Challenges in Cardiomyopathy Gene Therapy Clinical Trial Design

Gene therapy has emerged as a possible treatment for progressive, debilitating Mendelian cardiomyopathies with limited therapeutic options. This paper arises from discussions at the 2023 Cardiovascular Clinical Trialists Forum and highlights several challenges relevant to gene therapy clinical trials, including low prevalence and high phenotypic heterogeneity of Mendelian cardiomyopathies, outcome selection complexities and resulting regulatory uncertainty, and immune responses to the adeno-associated viral vectors that are being used in ongoing studies. Avenues to address these challenges such as natural history studies, external controls, novel regulatory pathways, and immunosuppression are discussed. Relevant cases of recent therapy approvals are highlighted. Ultimately, this work aims to broadly frame discussions on and provide potential future avenues for clinical trial design for rare cardiomyopathy gene therapies.

Ring-like late gadolinium enhancement: differential diagnosis and mimics

Advances in cardiac magnetic resonance have promoted tissue characterization with high spatial and contrast resolution, and late gadolinium enhancement (LGE) sequences have improved the detection of myocardial fibrosis. The distribution pattern of LGE facilitates differentiation between ischemic and nonischemic etiologies and aids in refining diagnoses within nonischemic cardiomyopathies, suggesting specific etiological factors. A distinctive nonischemic LGE pattern that has recently gained prominence is the ring-like pattern, defined as a subepicardial or mid-wall circumferential or semi-circumferential enhancement, which involves at least three contiguous segments within the same short-axis slice. Initially identified as a diagnostic marker for desmoplakin and filamin C-related cardiomyopathies, the pattern has been reported in nongenetic conditions; nevertheless, it remains an uncommon finding in these diseases. In this article, we aim to present the differential diagnoses of ring-like LGE and its mimics. The combination of epidemiological, clinical, electrocardiographic, and additional features enables a focused refinement of the differential diagnosis associated with ring-like LGE.

Genetic Causes of Sudden Cardiac Arrest in the Community

Background

Annually 300,000 Americans experience sudden cardiac arrest (SCA). Studies in referral SCA cohorts have observed rare variants in genes associated with arrhythmia and cardiomyopathy. We sought to: (1) establish the population prevalence of rare disease-causing variants in a set of candidate genes and (2) confirm the association of disease-causing variants in these genes with SCA in two prospective population-based studies.

Methods

SCA patients (n=3264) were accrued from the Oregon Sudden Unexpected Death Study and the PREdiction of Sudden death in mulTi-ethnic cOmmunities (PRESTO) study and compared to control patients (n=13713) from the Atherosclerosis Risk in Communities (ARIC) study. Whole genome sequencing was performed. Disease-causing (likely pathogenic or pathogenic) variants in candidate genes associated with arrhythmia/cardiomyopathy were identified using updated American College of Medical Genetics and Genomics criteria. Gene- collapsing case-control analysis was performed using the conditional logistic regression-sequence kernel association test.

Results

We identified 300 disease-causing variants, the majority of which were in cardiomyopathy genes (71%). There were 136 patients (4.2%) in the SCA group and 351 patients (2.6%) in the control group with one or more disease-causing variants (OR 1.66, 95% confidence interval 1.33-2.07, p<0.001). We identified 13 genes associated with an increased risk of SCA, nine associated with cardiomyopathy ( BAG3, DSC2, DSG2, FLNC, LMNA, MYBPC3, TNNI3, TNNT2, TTN ) and four with arrhythmia ( CACNA1C, CASQ2, KCNH2, KCNQ1 ).

Conclusions

Disease-causing variants in cardiomyopathy genes were the predominant genetic cause of SCA. These findings inform which genes to include in genetic screening for SCA.

Computational Medicine: What Electrophysiologists Should Know to Stay Ahead of the Curve

PURPOSE OF REVIEW

Technology drives the field of cardiac electrophysiology. Recent computational advances will bring exciting changes. To stay ahead of the curve, we recommend electrophysiologists develop a robust appreciation for novel computational techniques, including deterministic, statistical, and hybrid models.

RECENT FINDINGS

In clinical applications, deterministic models use biophysically detailed simulations to offer patient-specific insights. Statistical techniques like machine learning and artificial intelligence recognize patterns in data. Emerging clinical tools are exploring avenues to combine all the above methodologies. We review three ways that computational medicine will aid electrophysiologists by: (1) improving personalized risk assessments, (2) weighing treatment options, and (3) guiding ablation procedures. Leveraging clinical data that are often readily available, computational models will offer valuable insights to improve arrhythmia patient care. As emerging tools promote personalized medicine, physicians must continue to critically evaluate technology-driven tools they consider using to ensure their appropriate implementation.

Promise and Peril of a Genotype-First Approach to Mendelian Cardiovascular Disease

Precision medicine, which among other aspects includes an individual's genomic data in diagnosis and management, has become the standard-of-care for Mendelian cardiovascular disease (CVD). However, early identification and management of asymptomatic patients with potentially lethal and manageable Mendelian CVD through screening, which is the promise of precision health, remains an unsolved challenge. The reduced costs of genomic sequencing have enabled the creation of biobanks containing in-depth genetic and health information, which have facilitated the understanding of genetic variation, penetrance, and expressivity, moving us closer to the genotype-first screening of asymptomatic individuals for Mendelian CVD. This approach could transform health care by diagnostic refinement and facilitating prevention or therapeutic interventions. Yet, potential benefits must be weighed against the potential risks, which include evolving variant pathogenicity assertion or identification of variants with low disease penetrance; costly, stressful, and inappropriate diagnostic evaluations; negative psychological impact; disqualification for employment or of competitive sports; and denial of insurance. Furthermore, the natural history of Mendelian CVD is often unpredictable, making identification of those who will benefit from preventive measures a priority. Currently, there is insufficient evidence that population-based genetic screening for Mendelian CVD can reduce adverse outcomes at a reasonable cost to an extent that outweighs the harms of true-positive and false-positive results. Besides technical, clinical, and financial burdens, ethical and legal aspects pose unprecedented challenges. This review highlights key developments in the field of genotype-first approaches to Mendelian CVD and summarizes challenges with potential solutions that can pave the way for implementing this approach for clinical care.

Novel FLNC variants in pediatric cardiomyopathy: an insight into disease mechanisms

BACKGROUND

FLNC gene variants have predominantly been reported in adult populations with cardiomyopathies, and early-onset cases are less common. The genotype-phenotype relationship indicates that dilated cardiomyopathy (DCM) is often associated with FLNC truncating variants.

METHODS

We conducted a comprehensive genetic analysis using next generation sequencing (NGS) to identify FLNC variants in patients with cardiovascular conditions. Detailed phenotypic and variant analyses were performed to characterize the clinical features and genetic alterations. Minigene assays and structural modeling were used to investigate the pathogenicity caused by the identified variants.

RESULTS

In a cohort of 58 patients, novel heterozygous FLNC variants, c.3962A > T (p.Glu1321Val) and c.7543C > T (p.Leu2515Phe), were identified in patients presenting with dilated and mixed restrictive/hypertrophic cardiomyopathies, respectively. The c.3962A > T variant disrupted normal splicing, as demonstrated through the splicing prediction tool and minigene studies, further emphasizing its pathogenic potential.

CONCLUSION

For missense variants of FLNC in patients with DCM, the splicing effect of the variant should be carefully checked. Early detection and intervention are crucial given the high risk of sudden cardiac death and severe cardiac complications.

Non-dilated left ventricular cardiomyopathy with arrhythmias is commonly caused by the nonsense variant DSP:c.3793G>T in Slovenian patients

DSP-cardiomyopathy has recently been recognised as a specific type of cardiomyopathy. Using an in-house Mendelian disease registry, we aimed to identify probands with likely pathogenic or pathogenic DSP variants. We detected these variants in 4.8% and 77.8% of genotype-positive probands referred for dilated and non-dilated left ventricular cardiomyopathy (NDLVC), respectively. We identified six Slovenian probands with the DSP:c.3793G>T and characterised them along with further eight of their relatives at the molecular and phenotypic level. Medical records revealed NDLVC with arrhythmia in six individuals (five probands, one relative; 33 ± 14 years; three males, three females). All had subepicardial late gadolinium enhancement on cardiac MRI (CMRI), and five received an ICD. Four individuals (one proband, three relatives; 48 ± 14 years; all female) had no ECG and/or cardiac abnormalities on CMRI detected. Our analysis presents a Slovenian-specific molecular pathology of DSP cardiomyopathy, delineates the clinical manifestation of DSP:c.3793C>T, and thereby improves the understanding of the clinical outcomes associated with truncating DSP variants.

Natural History, Phenotype Spectrum and Clinical Outcomes of Desmin (DES)-Associated Cardiomyopathy

Background

Pathogenic/likely pathogenic (P/LP) desmin (DES) variants cause heterogeneous cardiomyopathy and/or skeletal myopathy phenotypes. Limited data suggest a high incidence of major adverse cardiac events (MACE), including cardiac conduction disease (CCD), sustained ventricular arrhythmias (VA), and heart failure (HF) events (HF hospitalization, LVAD/cardiac transplant, HF-related death), in patients with P/LP DES variants. However, pleiotropic presentation and small cohort sizes have limited clinical phenotype and outcome characterization.

Objectives

We aimed to describe the natural history, phenotype spectrum, familial penetrance and outcomes in patients with P/LP DES variants through a systematic review and individual patient data meta-analysis using published reports.

Methods

We searched Medline (PubMed) and Embase for studies that evaluated cardiac phenotypes in patients with P/LP DES variants. Cardiomyopathy diagnosis or occurrence of MACE were considered evidence of cardiac involvement/penetrance. Lifetime event-free survival from CCD, sustained VA, HF events, and composite MACE was assessed.

Results

Out of 4,212 screened publications, 71 met the inclusion criteria. A total of 230 patients were included (52.6% male, 52.2% probands, median age: 31 years [22.0; 42.8] at first evaluation, median follow-up: 3 years [0; 11.0]). Overall, 124 (53.9%) patients were diagnosed with cardiomyopathy, predominantly dilated cardiomyopathy (14.8%), followed by restrictive cardiomyopathy (13.5%), whereas other forms were less common: arrhythmogenic cardiomyopathy (7.0%), hypertrophic cardiomyopathy (6.1%), arrhythmogenic right ventricular cardiomyopathy (5.2%), and other forms (7.4%). Overall, 132 (57.4%) patients developed MACE, with 96 [41.7%] having CCD, 36 [15.7%] sustained VA, and 43 [18.7%] HF events. Familial penetrance of cardiac disease was 63.6% among relatives with P/LP DES variants. Male sex was associated with increased risk of sustained VA (HR 2.28, p=0.02) and HF events (HR 2.45, p=0.008).

Conclusions

DES cardiomyopathy exhibits heterogeneous phenotypes and distinct natural history, characterized by high familial penetrance and substantial MACE burden. Male patients face higher risk of sustained VA events.

A novel tool for arrhythmic risk stratification in desmoplakin gene variant carriers

BACKGROUND AND AIMS

Pathogenic desmoplakin (DSP) gene variants are associated with the development of a distinct form of arrhythmogenic cardiomyopathy known as DSP cardiomyopathy. Patients harbouring these variants are at high risk for sustained ventricular arrhythmia (VA), but existing tools for individualized arrhythmic risk assessment have proven unreliable in this population.

METHODS

Patients from the multi-national DSP-ERADOS (Desmoplakin SPecific Effort for a RAre Disease Outcome Study) Network patient registry who had pathogenic or likely pathogenic DSP variants and no sustained VA prior to enrolment were followed longitudinally for the development of first sustained VA event. Clinically guided, step-wise Cox regression analysis was used to develop a novel clinical tool predicting the development of incident VA. Model performance was assessed by c-statistic in both the model development cohort (n = 385) and in an external validation cohort (n = 86).

RESULTS

In total, 471 DSP patients [mean age 37.8 years, 65.6% women, 38.6% probands, 26% with left ventricular ejection fraction (LVEF) < 50%] were followed for a median of 4.0 (interquartile range: 1.6-7.3) years; 71 experienced first sustained VA events {2.6% [95% confidence interval (CI): 2.0, 3.5] events/year}. Within the development cohort, five readily available clinical parameters were identified as independent predictors of VA and included in a novel DSP risk score: female sex [hazard ratio (HR) 1.9 (95% CI: 1.1-3.4)], history of non-sustained ventricular tachycardia [HR 1.7 (95% CI: 1.1-2.8)], natural logarithm of 24-h premature ventricular contraction burden [HR 1.3 (95% CI: 1.1-1.4)], LVEF < 50% [HR 1.5 (95% CI: .95-2.5)], and presence of moderate to severe right ventricular systolic dysfunction [HR 6.0 (95% CI: 2.9-12.5)]. The model demonstrated good risk discrimination within both the development [c-statistic .782 (95% CI: .77-.80)] and external validation [c-statistic .791 (95% CI: .75-.83)] cohorts. The negative predictive value for DSP patients in the external validation cohort deemed to be at low risk for VA (<5% at 5 years; n = 26) was 100%.

CONCLUSIONS

The DSP risk score is a novel model that leverages readily available clinical parameters to provide individualized VA risk assessment for DSP patients. This tool may help guide decision-making for primary prevention implantable cardioverter-defibrillator placement in this high-risk population and supports a gene-first risk stratification approach.

Nuclear envelope lamin-related dilated cardiomyopathy: a case series including histopathology

Background

Lamin A/C gene (LMNA) mutations cause myocardial fibrosis manifesting as arrhythmogenic, non-compaction, or dilated cardiomyopathies. Fibro-fatty replacement largely involves the conduction system and conduction disease commonly occurs prior to contractile dysfunction.

Case summary

Two young, unrelated Caucasian males, aged 34 and 25, were referred to our centre for treatment of advanced heart failure. Both patients had a family history of heart failure and sudden cardiac death among their first-degree relatives and were diagnosed with Lamin A/C mutations, but they had not been screened prior to disease onset. Although the initial phenotypes were dilated cardiomyopathy and left ventricular non-compaction cardiomyopathy, both patients' disease progressed rapidly to include ventricular arrhythmias, severe global left ventricular hypokinesis, and dependence on outpatient milrinone to complete activities of daily living. Both patients received heart transplantation within 2 years of initial disease onset. The surgical pathology of the explanted hearts revealed characteristic findings of fibro-fatty degeneration of the conduction system, and using light microscopy, they were found to have nuclear membrane thinning, bubbling, and convolution throughout all areas sampled.

Discussion

Lamin A/C-related cardiomyopathy is associated with sudden cardiac death early in the disease course, warranting early consideration of implantable cardioverter defibrillator implantation, and rapid progression to end-stage cardiomyopathy refractory to standard medical therapies, necessitating early referral to an advanced heart failure centre. We report a newly observed and recorded finding of morphologic nuclear alterations in late-stage disease using high-power light microscopy. These alterations underscore the pathophysiology of Lamin A/C-related cardiomyopathy and provide a basis for future research into disease-specific therapies.

Risk Assessment and Personalized Treatment Options in Inherited Dilated Cardiomyopathies: A Narrative Review

Considering the worldwide impact of heart failure, it is crucial to develop approaches that can help us comprehend its root cause and make accurate predictions about its outcome. This is essential for lowering the suffering and death rates connected with this widespread illness. Cardiomyopathies frequently result from genetic factors, and the study of heart failure genetics is advancing quickly. Dilated cardiomyopathy (DCM) is the most prevalent kind of cardiomyopathy, encompassing both genetic and nongenetic abnormalities. It is distinguished by the enlargement of the left ventricle or both ventricles, accompanied by reduced contractility. The discovery of the molecular origins and subsequent awareness of the molecular mechanism is broadening our knowledge of DCM development. Additionally, it emphasizes the complicated nature of DCM and the necessity to formulate several different strategies to address the diverse underlying factors contributing to this disease. Genetic variants that can be transmitted from one generation to another can be a significant contributor to causing family or sporadic hereditary DCM. Genetic variants also play a significant role in determining susceptibility for acquired triggers for DCM. The genetic causes of DCM can have a large range of phenotypic expressions. It is crucial to select patients who are most probable to gain advantages from genetic testing. The purpose of this research is to emphasize the significance of identifying genetic DCM, the relationships between genotype and phenotype, risk assessment, and personalized therapy for both those affected and their relatives. This approach is expected to gain importance once treatment is guided by genotype-specific advice and disease-modifying medications.

Diagnosis and management of arrhythmogenic cardiomyopathy: a case report

Background

Arrhythmogenic cardiomyopathy (ACM) is a genetically determined myocardial atrophy which progressively extends from the epicardium towards the endocardium, resulting in wall thinning. It is one of the leading causes of sudden death in young people. Postmortem studies demonstrate that up to 70-80% of the cases have biventricular involvement. Variable penetrance and expressivity results in a wide phenotypic spectrum, challenging diagnostic accuracy of advanced multimodality imaging tools. Prompt recognition, non-invasive imaging, risk stratification for sudden cardiac death (SCD), and preventive measures are paramount to improve prognosis.

Case summary

Here, we present a 22-year-old Black male who was referred to our electrophysiology clinic with palpitations, remote syncope, and a family history of SCD. Over 3 years, he developed gradually worsening symptomatic palpitations. While physical exam and transthoracic echocardiography were unremarkable, his cardiac magnetic resonance imaging was consistent with biventricular ACM. Genetic testing confirmed ACM, revealing double heterozygosity in DSG2 and PKP2. Given the elevated estimated risk of life-threatening dysrhythmias, a subcutaneous cardiac defibrillator was successfully implanted.

Discussion

Frequently, patients with ACM have more than one mutation in the same gene (compound heterozygosity) or in a second gene (double heterozygosity). Genetic counselling is strongly recommended for family members of the proband. The diagnosis of ACM may be mimicked by other diseases (cardiac sarcoidosis, dilated cardiomyopathy, amyloidosis), thus genetic testing can be useful to determine the presence of the disease. The present report provides an overview of the clinical course, diagnostic criteria, risk stratification, and prognostication for patients with ACM.

Impact of DCM-Causing Genetic Background on Long-Term Response to Cardiac Resynchronization Therapy

BACKGROUND

Patients with nonischemic dilated cardiomyopathy (DCM), severe left ventricular (LV) dysfunction, and complete left bundle branch block benefit from cardiac resynchronization therapy (CRT). However, a large heterogeneity of response to CRT is described. Several predictors of response to CRT have been identified, but the role of the underlying genetic background is still poorly explored.

OBJECTIVES

In the present study, the authors sought to define differences in LV remodeling and outcome prediction after CRT when stratifying patients according to the presence or absence of DCM-causing genetic background.

METHODS

From our center, 74 patients with DCM subjected to CRT and available genetic testing were retrospectively enrolled. Carriers of causative monogenic variants in validated DCM-causing genes, and/or with documented family history of DCM, were classified as affected by genetically determined disease (GEN+DCM) (n = 25). Alternatively, by idiopathic dilated cardiomyopathy (idDCM) (n = 49). The primary outcome was long-term LV remodeling and prevalence of super response to CRT (evaluated at 24-48 months after CRT); the secondary outcome was heart failure-related death/heart transplant/LV assist device.

RESULTS

GEN+DCM and idDCM patients were homogeneous at baseline with the exception of QRS duration, longer in idDCM. The median follow-up was 55 months. Long-term LV reverse remodeling and the prevalence of super response were significantly higher in the idDCM group (27% in idDCM vs 5% in GEN+DCM; P = 0.025). The heart failure-related death/heart transplant/LV assist device outcome occurred more frequently in patients with GEN+DCM (53% vs 24% in idDCM; P = 0.028).

CONCLUSIONS

Genotyping contributes to the risk stratification of patients with DCM undergoing CRT implantation in terms of LV remodeling and outcomes.

Reduction of Filamin C Results in Altered Proteostasis, Cardiomyopathy, and Arrhythmias

BACKGROUND

Many cardiomyopathy-associated FLNC pathogenic variants are heterozygous truncations, and FLNC pathogenic variants are associated with arrhythmias. Arrhythmia triggers in filaminopathy are incompletely understood.

METHODS AND RESULTS

We describe an individual with biallelic FLNC pathogenic variants, p.Arg650X and c.970-4A>G, with peripartum cardiomyopathy and ventricular arrhythmias. We also describe clinical findings in probands with FLNC variants including Val2715fs87X, Glu2458Serfs71X, Phe106Leu, and c.970-4A>G with hypertrophic and dilated cardiomyopathy, atrial fibrillation, and ventricular tachycardia. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were generated. The FLNC truncation, Arg650X/c.970-4A>G, showed a marked reduction in filamin C protein consistent with biallelic loss of function mutations. To assess loss of filamin C, gene editing of a healthy control iPSC line was used to generate a homozygous FLNC disruption in the actin binding domain. Because filamin C has been linked to protein quality control, we assessed the necessity of filamin C in iPSC-CMs for response to the proteasome inhibitor bortezomib. After exposure to low-dose bortezomib, FLNC-null iPSC-CMs showed an increase in the chaperone proteins BAG3, HSP70 (heat shock protein 70), and HSPB8 (small heat shock protein B8) and in the autophagy marker LC3I/II. FLNC null iPSC-CMs had prolonged electric field potential, which was further prolonged in the presence of low-dose bortezomib. FLNC null engineered heart tissues had impaired function after low-dose bortezomib.

CONCLUSIONS

FLNC pathogenic variants associate with a predisposition to arrhythmias, which can be modeled in iPSC-CMs. Reduction of filamin C prolonged field potential, a surrogate for action potential, and with bortezomib-induced proteasome inhibition, reduced filamin C led to greater arrhythmia potential and impaired function.

Magnetic Resonance Imaging Characterization and Clinical Outcomes of Dilated and Arrhythmogenic Left Ventricular Cardiomyopathies

BACKGROUND

Nondilated left ventricular cardiomyopathy (NDLVC) has been recently differentiated from dilated cardiomyopathy (DCM). A comprehensive characterization of these 2 entities using cardiac magnetic resonance (CMR) and genetic testing has never been performed.

OBJECTIVES

This study sought to provide a thorough characterization and assess clinical outcomes in a large multicenter cohort of patients with DCM and NDLVC.

METHODS

A total of 462 patients with DCM (227) or NDLVC (235) with CMR data from 4 different referral centers were retrospectively analyzed. The study endpoint was a composite of sudden cardiac death or major ventricular arrhythmias.

RESULTS

In comparison to DCM, NDLVC had a higher prevalence of pathogenic or likely pathogenic variants of arrhythmogenic genes (40% vs 23%; P < 0.001), higher left ventricular (LV) systolic function (LV ejection fraction: 51% ± 12% vs 36% ± 15%; P < 0.001) and higher prevalence of free-wall late gadolinium enhancement (LGE) (27% vs 14%; P < 0.001). Conversely, DCM showed higher prevalence of pathogenic or likely pathogenic variants of nonarrhythmogenic genes (23% vs 12%; P = 0.002) and septal LGE (45% vs 32%; P = 0.004). Over a median follow-up of 81 months (Q1-Q3: 40-132 months), the study outcome occurred in 98 (21%) patients. LGE with septal location (HR: 1.929; 95% CI: 1.033-3.601; P = 0.039) was independently associated with the risk of sudden cardiac death or major ventricular arrhythmias together with LV dilatation, older age, advanced NYHA functional class, frequent ventricular ectopic activity, and nonsustained ventricular tachycardia.

CONCLUSIONS

In a multicenter cohort of patients with DCM and NDLVC, septal LGE together with LV dilatation, age, advanced disease, and frequent and repetitive ventricular arrhythmias were powerful predictors of major arrhythmic events.

Predicted Deleterious Variants in Cardiomyopathy Genes Prognosticate Mortality and Composite Outcomes in the UK Biobank

BACKGROUND

Inherited cardiomyopathies present with broad variation of phenotype. Data are limited regarding genetic screening strategies and outcomes associated with predicted deleterious variants in cardiomyopathy-associated genes in the general population.

OBJECTIVES

The authors aimed to determine the risk of mortality and composite cardiomyopathy-related outcomes associated with predicted deleterious variants in cardiomyopathy-associated genes in the UK Biobank.

METHODS

Using whole exome sequencing data, variants in dilated, hypertrophic, and arrhythmogenic right ventricular cardiomyopathy-associated genes with at least moderate evidence of disease causality according to ClinGen Expert Panel curations were annotated using REVEL (≥0.65) and ANNOVAR (predicted loss-of-function) considering gene-disease mechanisms. Genotype-positive and genotype-negative groups were compared using time-to-event analyses for the primary (all-cause mortality) and secondary outcomes (diagnosis of cardiomyopathy; composite outcome of diagnosis of cardiomyopathy, heart failure, arrhythmia, stroke, and death).

RESULTS

Among 200,619 participants (age at recruitment 56.46 ± 8.1 years), 5,292 (2.64%) were found to host ≥1 predicted deleterious variants in cardiomyopathy-associated genes (CMP-G+). After adjusting for age and sex, CMP-G+ individuals had higher risk for all-cause mortality (HR: 1.13 [95% CI: 1.01-1.25]; P = 0.027), increased risk for being diagnosed with cardiomyopathy later in life (HR: 5.75 [95% CI: 4.58-7.23]; P < 0.0001), and elevated risk for composite outcome (HR: 1.29 [95% CI: 1.20-1.39]; P < 0.0001) than CMP-G- individuals. The higher risk for being diagnosed with cardiomyopathy and composite outcomes in the genotype-positive subjects remained consistent across all cardiomyopathy subgroups.

CONCLUSIONS

Adults with predicted deleterious variants in cardiomyopathy-associated genes exhibited a slightly higher risk of mortality and a significantly increased risk of developing cardiomyopathy, and cardiomyopathy-related composite outcomes, in comparison with genotype-negative controls.

Clinical Genetic and Genomic Testing in Congenital Heart Disease and Cardiomyopathy

Congenital heart disease (CHD) and cardiomyopathies are the leading cause of morbidity and mortality worldwide. These conditions are often caused by genetic factors, and recent research has shown that genetic and genomic testing can provide valuable information for patient care. By identifying genetic causes, healthcare providers can screen for other related health conditions, offer early interventions, estimate prognosis, select appropriate treatments, and assess the risk for family members. Genetic and genomic testing is now the standard of care in patients with CHD and cardiomyopathy. However, rapid advances in technology and greater availability of testing options have led to changes in recommendations for the most appropriate testing method. Several recent studies have investigated the utility of genetic testing in this changing landscape. This review summarizes the literature surrounding the clinical utility of genetic evaluation in patients with CHD and cardiomyopathy.

Long-Term Arrhythmic Follow-Up and Risk Stratification of Patients With Desmoplakin-Associated Arrhythmogenic Right Ventricular Cardiomyopathy

Background

Patients with likely pathogenic/pathogenic desmoplakin (DSP) variants are poorly characterized. Some of them meet diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC), but it is unclear how risk stratification strategies for ARVC perform in this setting.

Objectives

The purpose of this study was to characterize arrhythmic outcomes and to test the performance of the recently validated ARVC risk calculator in patients with DSP likely pathogenic/pathogenic variants fulfilling definite 2010 ARVC Task Force Criteria (DSP-TFC+).

Methods

DSP-TFC+ patients were enrolled from 20 institutions across 3 continents. Ventricular arrhythmias (VA), defined as a composite of sustained ventricular tachycardia (VT), appropriate implantable cardioverter defibrillator therapies, and ventricular fibrillation/sudden cardiac death events in follow-up, were reported as the primary outcome. We tested the performance of the ARVC risk calculator for VA prediction, reporting c-statistics.

Results

Among 252 DSP-TFC+ patients (age 39.6 ± 16.9 years, 35.3% male), 94 (37.3%) experienced VA over 44.5 [IQR: 19.6-78.3] months. Patients with left ventricle involvement (n = 194) were at higher VA risk (log-rank P = 0.0239). History of nonsustained VT (aHR 2.097; P = 0.004) showed the strongest association with VA occurrence during the first 5-year follow-up. Neither age (P = 0.723) nor male sex (P = 0.200) was associated with VAs at follow-up. In 204 patients without VA at diagnosis, incident VA rate was high (32.8%; 7.37%/y). The ARVC risk calculator performed poorly overall (c-statistic 0.604 [0.594-0.614]) and very poorly in patients with left ventricular disease (c-statistic 0.558 [0.556-0.560]).

Conclusions

DSP-TFC+ patients are at substantial risk for VAs. The ARVC risk calculator performs poorly in DSP-TFC+ patients suggesting need for a gene-specific risk algorithm. Meanwhile, DSP-TFC+ patients with nonsustained VT should be considered as high-risk.

Primate Model Carrying LMNA Mutation Develops Dilated Cardiomyopathy

To solve the clinical transformation dilemma of lamin A/C (LMNA)-mutated dilated cardiomyopathy (LMD), we developed an LMNA-mutated primate model based on the similarity between the phenotype of primates and humans. We screened out patients with LMD and compared the clinical data of LMD with TTN-mutated and mutation-free dilated cardiomyopathy to obtain the unique phenotype. After establishment of the LMNA c.357-2A>G primate model, primates were continuously observed for 48 months, and echocardiographic, electrophysiological, histologic, and transcriptional data were recorded. The LMD primate model was found to highly simulate the phenotype of clinical LMD. In addition, the LMD primate model shared a similar natural history with humans.

Role of arrhythmic phenotype in prognostic stratification and management of dilated cardiomyopathy

AIMS

Dilated cardiomyopathy (DCM) with arrhythmic phenotype combines phenotypical aspects of DCM and predisposition to ventricular arrhythmias, typical of arrhythmogenic cardiomyopathy. The definition of DCM with arrhythmic phenotype is not universally accepted, leading to uncertainty in the identification of high-risk patients. This study aimed to assess the prognostic impact of arrhythmic phenotype in risk stratification and the correlation of arrhythmic markers with high-risk arrhythmogenic gene variants in DCM patients.

METHODS AND RESULTS

In this multicentre study, DCM patients with available genetic testing were analysed. The following arrhythmic markers, present at baseline or within 1 year of enrolment, were tested: unexplained syncope, rapid non-sustained ventricular tachycardia (NSVT), ≥1000 premature ventricular contractions/24 h or ≥50 ventricular couplets/24 h. LMNA, FLNC, RBM20, and desmosomal pathogenic or likely pathogenic gene variants were considered high-risk arrhythmogenic genes. The study endpoint was a composite of sudden cardiac death and major ventricular arrhythmias (SCD/MVA). We studied 742 DCM patients (45 ± 14 years, 34% female, 410 [55%] with left ventricular ejection fraction [LVEF] <35%). During a median follow-up of 6 years (interquartile range 1.6-12.1), unexplained syncope and NSVT were the only arrhythmic markers associated with SCD/MVA, and the combination of the two markers carried a significant additive risk of SCD/MVA, incremental to LVEF and New York Heart Association class. The probability of identifying an arrhythmogenic genotype rose from 8% to 30% if both early syncope and NSVT were present.

CONCLUSION

In DCM patients, the combination of early detected NSVT and unexplained syncope increases the risk of life-threatening arrhythmic outcomes and can aid the identification of carriers of malignant arrhythmogenic genotypes.

Apoptosis, a useful marker in the management of hot-phase cardiomyopathy?

AIMS

'Hot phases', characterized by chest pain and troponin release, may represent the first clinical presentation of arrhythmogenic cardiomyopathies. Differential diagnosis with acute myocarditis is an unmet challenge for the clinicians. We sought to investigate histological and genetic features in patients with cardiomyopathy presenting with hot phases.

METHODS AND RESULTS

We evaluated a case series of consecutive patients hospitalized for suspected 'hot-phase cardiomyopathy' in two Italian centres from June 2017 to March 2022 (median follow-up 18 months) that underwent both endomyocardial biopsy (EMB) and genetic testing. Apoptosis was confirmed with TUNEL assay. Among the 17 enrolled patients (mean age 34 ± 15 years, 76% male), only six patients (35%) presented standard histological and immunohistochemical markers for significant cardiac inflammation at EMB. Conversely, apoptosis was found in 13 patients (77%). Genetic testing was positive for a pathogenic/likely pathogenic (P/LP) variant in genes involved in cardiomyopathies (most frequently in DSP) in eight patients (48%), rising to 62% among patients with apoptosis on EMB. Notably, all patients without apoptosis tested negative for P/LP disease-related variants. Left ventricular ejection fraction was lower in patients showing apoptosis at EMB compared to those without (p = 0.003).

CONCLUSIONS

Apoptosis, rather than significant inflammation, was mostly prevalent in this case series of patients with 'hot-phase' presentation, especially in carriers of variants in cardiomyopathy-related genes. Detecting apoptosis on EMB might guide clinicians in performing genetic testing and in more tailored therapeutic choices in 'hot-phase cardiomyopathy'.

Arrhythmogenic Right Ventricular Cardiomyopathy Post-Mortem Assessment: A Systematic Review

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disorder characterized by the progressive fibro-fatty replacement of the right ventricular myocardium, leading to myocardial atrophy. Although the structural changes usually affect the right ventricle, the pathology may also manifest with either isolated left ventricular myocardium or biventricular involvement. As ARVC shows an autosomal dominant pattern of inheritance with variable penetrance, the clinical presentation of the disease is highly heterogeneous, with different degrees of severity and patterns of myocardial involvement even in patients of the same familiar group with the same gene mutation: the pathology spectrum ranges from the absence of symptoms to sudden cardiac death (SCD) sustained by ventricular arrhythmias, which may, in some cases, be the first manifestation of an otherwise silent pathology. An evidence-based systematic review of the literature was conducted to evaluate the state of the art of the diagnostic techniques for the correct post-mortem identification of ARVC. The research was performed using the electronic databases PubMed and Scopus. A methodological approach to reach a correct post-mortem diagnosis of ARVC was described, analyzing the main post-mortem peculiar macroscopic, microscopic and radiological alterations. In addition, the importance of performing post-mortem genetic tests has been underlined, which may lead to the correct identification and characterization of the disease, especially in those ARVC forms where anatomopathological investigation does not show evident morphostructural damage. Furthermore, the usefulness of genetic testing is not exclusively limited to the correct diagnosis of the pathology, but is essential for promoting targeted screening programs to the deceased's family members. Nowadays, the post-mortem diagnosis of ARVC performed by forensic pathologist remains very challenging: therefore, the identification of a clear methodological approach may lead to both a reduction in under-diagnoses and to the improvement of knowledge on the disease.

Natural History of Dilated Cardiomyopathy Due to c.77T>C (p.Val26Ala) in Emerin Protein

(1) Introduction: Dilated cardiomyopathy (DCM) mainly affects young individuals and is the main indication of heart transplantation. The variant c.77T>C (p.Val26Ala) of the gene coding for emerin (EMD) in chromosome Xq28 has been catalogued as a pathogenic variant for the development of DCM, exhibiting an X-linked inheritance pattern. (2) Methods: A retrospective study was conducted covering the period 2015-2023 in patients with DCM of genetic origin. The primary endpoint was patient age at onset of the first composite major cardiac event, in the form of a first episode of heart failure, malignant ventricular arrhythmia, or end-stage heart failure, according to the presence of truncating variant in titin gene (TTNtv) versus the p.Val26Ala mutation in the EMD protein. (3) Results: A total of 31 and 22 patients were included in the EMD group and TTNtv group, respectively. The primary endpoint was significantly higher in the EMD group, with a hazard ratio of 4.16 (95% confidence interval: 1.83-9.46; p = 0.001). At 55 years of age, all the patients in the EMD group had already presented heart failure, nine presented malignant ventricular arrhythmia (29%), and 13 required heart transplantation (42%). (4) Conclusions: DCM secondary to the c.77T>C (p.Val26Ala) mutation in the EMD gene is associated to an increased risk of major cardiac events compared to patients with DCM due to TTNtv, with a large proportion of transplanted patients in the fifth decade of life.

Valvular heart disease and cardiomyopathy: reappraisal of their interplay

Cardiomyopathies and valvular heart diseases are typically considered distinct diagnostic categories with dedicated guidelines for their management. However, the interplay between these conditions is increasingly being recognized and they frequently coexist, as in the paradigmatic examples of dilated cardiomyopathy and hypertrophic cardiomyopathy, which are often complicated by the occurrence of mitral regurgitation. Moreover, cardiomyopathies and valvular heart diseases can have a shared aetiology because several genetic or acquired diseases can affect both the cardiac valves and the myocardium. In addition, the association between cardiomyopathies and valvular heart diseases has important prognostic and therapeutic implications. Therefore, a better understanding of their shared pathophysiological mechanisms, as well as of the prevalence and predisposing factors to their association, might lead to a different approach in the risk stratification and management of these diseases. In this Review, we discuss the different scenarios in which valvular heart diseases and cardiomyopathies coexist, highlighting the need for an improved classification and clustering of these diseases with potential repercussions in the clinical management and, particularly, personalized therapeutic approaches.

Catheter Ablation for Ventricular Tachycardia in Patients With Desmoplakin Cardiomyopathy

BACKGROUND

Desmoplakin (DSP) pathogenic/likely pathogenic (P/LP) variants are associated with malignant phenotypes of arrhythmogenic cardiomyopathy (DSP-ACM). Reports of outcomes after ventricular tachycardia (VT) ablation in DSP-ACM are scarce.

OBJECTIVES

In this study, the authors sought to report on long-term outcomes of VT ablation in DSP-ACM.

METHODS

Patients with P/LP DSP variants at 9 institutions undergoing VT ablation were included. Demographic, clinical, and instrumental data as well as all ventricular arrhythmia (VA) events were collected. Sustained VAs after the index procedure were the primary outcome. A per-patient before and after ablation comparison of rates of VA episodes per year was performed as well.

RESULTS

Twenty-four DSP-ACM patients (39.3 ± 12.1 years of age, 62.5% male, median 6,116 [Q1-Q3: 3,362-7,760] premature ventricular complexes [PVCs] per 24 hours, median 4 [Q1-Q3: 2-11] previous VA episodes per patient at ablation) were included. Index procedure was most commonly endocardial/epicardial (19/24) The endocardium of the right ventricle (RV), the left ventricle (LV), or both ventricles were mapped in 8 (33.3%), 9 (37.5%), and 7 (29.2%) cases, respectively. Low voltage potentials were found in 10 of 15 patients in the RV and 11 of 16 in the LV. Endocardial ablation was performed in 18 patients (75.0%). Epicardial mapping in 19 patients (79.2%) identified low voltage potentials in 17, and 16 received epicardial ablation. Over the following 2.9 years (Q1-Q3: 1.8-5.5 years), 13 patients (54.2%) experienced VA recurrences. A significant reduction in per-patient event/year before and after ablation was observed (1.4 [Q1-Q3: 0.5-2.4] to 0.1 [Q1-Q3: 0.0-0.4]; P = 0.009). 2 patients needed heart transplantation, and 4 died (3 of heart failure and 1 noncardiac death).

CONCLUSIONS

VT ablation in DSP-ACM is effective in reducing the VA burden of the disease, but recurrences are common. Most VT circuits are epicardial, with both LV and RV low voltage abnormalities. Heart failure complicates clinical course and is an important cause of mortality.

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.

Generation of human induced pluripotent stem cell line EURACi015-A from a patient affected by dilated cardiomyopathy carrying the Lamin A/C p.Glu161Lys mutation

Dilated cardiomyopathy (DCM) is a common heart disorder caused by genetic and non-genetic etiologies, characterized by left ventricular dilatation and contractile dysfunction. Here, we created a human induced pluripotent stem cell line from peripheral blood mononuclear cells using non-integrating vectors from a patient carrying a heterozygous LMNA variant (c.481G > A, p.Glu161Lys, NM_170707.4). The obtained EURACi015-A line, showed the typical morphology of pluripotent cells, normal karyotype and exhibited pluripotency markers and a trilineage differentiation potential. This cell line can be successfully differentiated into cardiomyocytes and endothelial cells. This line represents a human in vitro model to study the genetic basis of DCM.

Changes of ubiquitylated proteins in atrial fibrillation associated with heart valve disease: proteomics in human left atrial appendage tissue

Background

Correlations between posttranslational modifications and atrial fibrillation (AF) have been demonstrated in recent studies. However, it is still unclear whether and how ubiquitylated proteins relate to AF in the left atrial appendage of patients with AF and valvular heart disease.

Methods

Through LC-MS/MS analyses, we performed a study on tissues from eighteen subjects (9 with sinus rhythm and 9 with AF) who underwent cardiac valvular surgery. Specifically, we explored the ubiquitination profiles of left atrial appendage samples.

Results

In summary, after the quantification ratios for the upregulated and downregulated ubiquitination cutoff values were set at >1.5 and <1:1.5, respectively, a total of 271 sites in 162 proteins exhibiting upregulated ubiquitination and 467 sites in 156 proteins exhibiting downregulated ubiquitination were identified. The ubiquitylated proteins in the AF samples were enriched in proteins associated with ribosomes, hypertrophic cardiomyopathy (HCM), glycolysis, and endocytosis.

Conclusions

Our findings can be used to clarify differences in the ubiquitination levels of ribosome-related and HCM-related proteins, especially titin (TTN) and myosin heavy chain 6 (MYH6), in patients with AF, and therefore, regulating ubiquitination may be a feasible strategy for AF.