2019 HRS expert consensus statement on evaluation, risk stratification, and management of arrhythmogenic cardiomyopathy

Genomics of pediatric cardiomyopathy

Cardiomyopathy in children is a leading cause of heart failure and cardiac transplantation. Disease-associated genetic variants play a significant role in the development of the different subtypes of disease. Genetic testing is increasingly being recognized as the standard of care for diagnosing this heterogeneous group of disorders, guiding management, providing prognostic information, and facilitating family-based risk stratification. The increase in clinical and research genetic testing within the field has led to new insights into this group of disorders. Mutations in genes encoding sarcomere, cytoskeletal, Z-disk, and sarcolemma proteins appear to play a major role in causing the overlapping clinical phenotypes called cardioskeletal myopathies through "final common pathway" links. For myocarditis, the high frequency of infectious exposures and wide spectrum of presentation suggest that genetic factors mediate the development and course of the disease, including genetic risk alleles, an association with cardiomyopathy, and undiagnosed arrhythmogenic cardiomyopathy. Finally, while we have made strides in elucidating the genetic architecture of pediatric cardiomyopathy, understanding the clinical implications of variants of uncertain significance remains a major issue. The need for continued genetic innovation in this field remains great, particularly as a basis to drive forward targeted precision medicine and gene therapy efforts. IMPACT: Cardiomyopathy and skeletal myopathy can occur in the same patient secondary to gene mutations that encode for sarcomeric or cytoskeletal proteins, which are expressed in both muscle groups, highlighting that there are common final pathways of disease. The heterogeneous presentation of myocarditis is likely secondary to a complex interaction of multiple environmental and genetic factors, suggesting a utility to genetic testing in pediatric patients with myocarditis, particularly those in higher risk groups. Given the high prevalence of variants of uncertain significance in genetic testing, better bioinformatic tools and pipelines are needed to resolve their clinical meaning.

Yield of family screening for dilated cardiomyopathy: 10-year experience at a multidisciplinary cardiogenetic outpatient clinic

INTRODUCTION

Current family screening approaches in dilated cardiomyopathy (DCM) depend on the presence or absence of a familial genetic variant, in which variant pathogenicity (i.e. benign or pathogenic) classification drives screening recommendations. However, this approach has never been systematically evaluated.

METHODS

To describe the yield of DCM family screening stratified by variant classification in the Netherlands, we included 358 relatives (mean age ± standard deviation: 44.4 ± 15.9 years at baseline; 52% female; 41% (likely) pathogenic (LP/P) variant carriers from 210 families). Demographics, symptoms and genetic/cardiac test results were obtained. Endpoints were the development of DCM (left ventricular ejection fraction < 50% of non-ischaemic aetiology) or occurrence of major adverse cardiovascular events (MACE) (i.e. heart failure hospitalisation, ventricular arrhythmia or death). Probability of DCM or MACE was assessed with the Kaplan-Meier method.

RESULTS

DCM was present in 32 relatives (9%) (25/32 (78%) with LP/P variant) at baseline and in an additional 10/97 relatives (10%) (9/10 (90%) with LP/P variant) who were re-evaluated during a median follow-up time of 5.0 years (interquartile range: 3.2-7.4). Of the 128 relatives without the familial LP/P variant, none developed DCM. MACE was experienced by 5 relatives (1%) (4/5 (80%) with LP/P variant), all of whom had DCM at the time of the event.

CONCLUSION

The yield of DCM family screening was ~10% at baseline and another ~10% during 5‑year follow-up. Relatives without the familial LP/P variant could be safely discharged. These results reinforce the use of a genetics-first screening approach in relatives from families with an LP/P variant. This will lower the burden on resources in Dutch hospitals and help allocate resources to those who are most likely to benefit.

Desmoplakin Cardiomyopathy: Role of Inflammation and Potential Role of Disease-Modifying Therapies

PURPOSE OF REVIEW

To summarize the available data on the use of immunosuppression therapies for the management of hot phases of disease and recurrent myocarditis in patients with desmoplakin cardiomyopathy (DSP-CMP).

RECENT FINDINGS

Occurrence of myocarditis episodes has been associated with worsening of outcomes in DSP-CMP. Multiple case reports and small case series have described potential benefit in using anti-inflammatory and immunosuppressive medications for the treatment of those episodes. Recently published translational data has shown a clear link between DSP variants and a propensity to inflammation. The presence of acute myocarditis episodes have been clearly demonstrated as a manifestation of DSP-CMP. These episodes are marked by myocardial inflammation and subsequent fibrosis, and, moreover, contribute to a heightened future risk of subsequent arrhythmias and heart failure. Identifying optimal strategies to prevent and/or interrupt myocardial inflammation is therefore a critical priority of patients with DSP-CMP.

Advances in genetic diagnosis and therapy of hereditary heart disease: a bibliometric review from 2004 to 2024

Hereditary heart disease (HHD) is a series of cardiac disorders associated with monogenic or polygenic abnormalities and is one of the leading causes of sudden death, particularly in young adults. The updated European Cardiology guideline for cardiomyopathies provides the first comprehensive summary of genotyping, imaging, and therapy recommendations for inherited cardiomyopathies, but still lacks a comprehensive discussion of research advances and future trends in genetic diagnosis and therapy of HHD. Our research aims to fill this gap. Bibliometric analysis software (CiteSpace 6.3.R1, VOSviewer 1.6.18, and Scimago Graphica) was used to analyze the general information, trends, and emerging foci of HHD in the past 20 years, including author, country, institution, keyword, and so on. There were 5,757 publications were screened and aggregated in the database, including 1876 reviews and 3,881 articles. Hypertrophic cardiomyopathy (HCM), arrhythmogenic cardiomyopathy (ACM), Brugada syndrome (BrS), myocardial amyloidosis, and Fabry disease (FD) were the main types of HHD that were explored in greater depth. Moreover, new diagnostic methods, clinical cohorts, and genetically targeted therapies for HHD patients are key research hotspots. The relationship between the pathogenicity of genes and prognosis will become increasingly important for therapy.

The role of genetic testing in management and prognosis of individuals with inherited cardiomyopathies

Inherited cardiomyopathies are a heterogeneous group of heart muscle conditions where disease classification has traditionally been based on clinical characteristics. However, this does not always align with genotype. While there are well described challenges of genetic testing, understanding the role of genotype in patient management is increasingly required. We take a gene-by-gene approach, reviewing current evidence for the role of genetic testing in guiding prognosis and management of individuals with inherited cardiomyopathies. In particular, focusing on causal variants in genes definitively associated with arrhythmogenic cardiomyopathy, dilated cardiomyopathy, and hypertrophic cardiomyopathy. This review identifies genotype-specific disease sub-groups with strong evidence supporting the use of genetics in clinical management and highlights that at present, the spectrum of clinical utility is not reflected in current guidelines. Of 13 guideline or expert consensus statements for management of cardiomyopathies, there are seven gene-specific therapeutic recommendations that have been published from four documents. Understanding how genotype influences phenotype provides evidence for the role of genetic testing for prognostic and therapeutic purposes, moving us closer to precision-medicine based care.

Ventricular Depolarization Abnormalities and Their Role in Cardiac Risk Stratification - A Narrative Review

Ventricular depolarization refers to the electrical activation and subsequent contraction of the ventricles, visible as the QRS complex on a 12-lead electrocardiogram (ECG). A well-organized and efficient depolarization is critical for cardiac function. Abnormalities in ventricular depolarization may indicate various pathologies and can be present in all leads if the condition is general, or in a subgroup of anatomically contiguous leads if the condition is limited to the corresponding anatomic location of the heart. Furthermore, the assessment of depolarization abnormalities on the ECG may either be identified visually or this may depend on further processing. In recent decades, assessment of depolarization abnormalities has received a lot of attention for cardiac risk stratification. This risk stratification aims to identify patients at high risk of adverse cardiac events, to tailor preventive or therapeutic interventions. In this review, we provide an oversight of different techniques for assessing abnormal ventricular depolarization and their value in diagnosing certain conditions, in risk stratification of adverse events, and in guiding therapeutic decisions. This includes QRS alterations directly corresponding to cardiac conditions, such as bundle branch blocks, or the presence of a delta wave, and also metrics aiming to qualitatively or quantitatively assess myocardial scarring, such as QRS (micro)fragmentation and QRS-scoring, and techniques assessing abnormal late depolarizations, such as signal-averaged ECG. While most established assessments of abnormal depolarization rely on human interpretation and are limited by visual detection, recently introduced analyses, such as QRS micro-fragmentation, aim to tackle these limitations. Besides eliminating bias, these automated analyses bypass the need for human interpretation, thereby paving the way for large population studies.

A right ventricular bulge: A clinical dilemma in diagnosis

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disease characterized by progressive fibrofatty tissue replacement of the myocardium. Asymptomatic individuals can often present for the first time with acute cardiac symptoms, such as syncope and ventricular arrhythmias or sudden cardiac death (SCD), which can occur in young and athletic populations. In the field of inherited cardiomyopathies, ARVC is one of the most challenging to diagnose due to its variable expressivity, incomplete penetrance, and lack of specific, unique diagnostic criteria. Without additional clinical findings or context, current imaging modalities are unable to definitively distinguish ARVC from other disease entities. Right ventricular (RV) structural changes can lead to prominent ARVC features. An important component of the 2010 revised task force criteria (TFC) is the assessment of RV wall motion contraction by echocardiography; however, this can be difficult to assess. This case report explores the diagnostic criteria used for ARVC and the role of RV wall motion contraction in the diagnosis.

Endurance exercise promotes episodes of myocardial injury in individuals with a pathogenic desmoplakin (DSP) variant

BACKGROUND

Desmoplakin (DSP) variants are associated with left predominant or biventricular arrhythmogenic cardiomyopathy. Exercise promotes penetrance and sustained ventricular arrhythmias (VAs) in right-sided arrhythmogenic right ventricular cardiomyopathy, but its effect is unknown in DSP variant carriers.

OBJECTIVE

The purpose of this study was to assess whether exercise is associated with clinical outcomes in individuals with a pathogenic or likely pathogenic DSP variant.

METHODS

Adults with a pathogenic or likely pathogenic DSP variant were interviewed about physical activity from age 10. Endurance athletes were defined on the basis of a mean exercise dose >24 metabolic equivalent hours per week of moderate- to vigorous-intensity exercise. Lifetime survival free of VA (ventricular tachycardia/fibrillation or appropriate implantable cardioverter-defibrillator therapy), clinical heart failure (HF) (presentation to the emergency department or hospitalization with HF), and myocardial injury events characteristic of DSP cardiomyopathy (symptoms, elevated troponin, and imaging with nonobstructive coronaries) were examined using the Kaplan-Meier method and Cox regression models.

RESULTS

Participants (N=100; 66% female; mean age 36 ± 15 years) were active with a median 28.4 (interquartile range 14.8-46) metabolic equivalent hours per week of pre-baseline evaluation exercise, and just 8 individuals continued athlete-level exercise post-baseline evaluation. In multivariable analyses, endurance athletes (60%) had no worse survival free of VA (hazard ratio [HR] 1.00; 95% confidence interval [CI] 0.5-1.98) or clinical HF (HR 0.86; 95% CI 0.36-2.05) but their risk of myocardial injury was elevated (HR 2.37; 95% CI 1.11-5.05). Furthermore, myocardial injury episodes were strongly associated with an elevated risk of both VA (HR 7.86; 95% CI 3.56-17.33) and clinical HF (HR 10.28; 95% CI 2.95-35.83) thereafter.

CONCLUSION

Endurance exercise may promote progression of DSP cardiomyopathy by increasing the risk of myocardial injury episodes, but the effect on VA and clinical HF is less clear. This study informs shared decision-making exercise and sport participation discussions.

Heritable Burden of Community Sudden Death by Autopsy and Molecular Phenotyping for Precision Genotype Correlation

BACKGROUND

Sudden cardiac death (SCD) genetic studies neglect the majority occurring in older decedents with cardiovascular pathology.

OBJECTIVES

This study sought to determine the burden of genetic disease in unselected adult sudden deaths by precision genotype-postmortem phenotype correlation.

METHODS

The authors used autopsy, histology, and toxicology to adjudicate cause and identify high-suspicion phenotypes (eg, hypertrophic cardiomyopathy) among presumed SCDs aged 18 to 90 years referred to the county medical examiner from February 2011 to January 2018. They tested 231 genes associated with sudden death and correlated genotype with postmortem phenotypes, including myocardial analysis. Family history in high-suspicion phenotype cases was obtained.

RESULTS

Of 856 autopsied presumed SCDs, families of 359 consented and 306 cases (66% cardiac cause) ultimately underwent genetic testing (mean age 62 years, 74% male). Seventy-five cases met high-suspicion phenotype criteria (8.8%), of which 36 underwent testing; 18 families met with a genetic counselor. We found 14 cases with autosomal dominant or X-linked pathogenic/likely pathogenic (P/LP) variants (apparent yield 4.6%); 6 had concordant cause (corrected yield 2%). Yields restricted to autopsy-confirmed cardiac causes (2.5%) and high-suspicion phenotypes (2.7%) were similar. Myocardial genotyping in 14 high-suspicion decedents matched negative blood genotyping, thus did not support somatic mosaicism. Myocardial RNA in a P/LP PKP2 carrier without phenotype demonstrated nonsense-mediated escape as potential mechanism for incomplete penetrance. One-half of high-suspicion cases had a family history of a related condition or sudden death.

CONCLUSIONS

In this 7-year countywide study, 2% of total sudden deaths and 2.5% of confirmed SCDs had identifiable genetic cause, corrected for genotype-phenotype concordance. These results do not support routine genetic testing for community sudden deaths, particularly without autopsy.

A new prediction model for sustained ventricular tachycardia in arrhythmogenic cardiomyopathy

Background

Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy characterized by high risks of sustained ventricular tachycardia (sVT) and sudden cardiac death. Identifying patients with high risk of sVT is crucial for the management of ACM.

Methods

A total of 147 ACM patients were retrospectively enrolled in the observational study and divided into training and validation groups. The least absolute shrinkage and selection operator (LASSO) regression model was employed to identify factors associated with sVT. Subsequently, a nomogram was constructed based on multivariable logistic regression analysis. The performance of the nomogram was evaluated using the area under the curve (AUC) of the receiver operating characteristic (ROC) curve and calibration curve. Decision curve analysis was conducted to assess the clinical utility of the nomogram.

Results

Seven parameters were incorporated into the nomogram: age, male sex, syncope, heart failure, T wave inversion in precordial leads, left ventricular ejection fraction (LVEF), SDNN level. The AUC of the nomogram to predict the probability of sVT was 0.867 (95% CI, 0.797-0.938) in the training group and 0.815 (95% CI, 0.673-0.958) in the validation group. The calibration curve demonstrated a good consistency between the actual clinical results and the predicted outcomes. Decision curve analysis indicated that the nomogram had higher overall net benefits in predicting sVT.

Conclusion

We have developed and internally validated a new prediction model for sVT in ACM. This model could serve as a valuable tool to accurately identify ACM patients with high risk of sVT.

Artificial Intelligence Advancements in Cardiomyopathies: Implications for Diagnosis and Management of Arrhythmogenic Cardiomyopathy

PURPOSE OF REVIEW

This review aims to explore the emerging potential of artificial intelligence (AI) in refining risk prediction, clinical diagnosis, and treatment stratification for cardiomyopathies, with a specific emphasis on arrhythmogenic cardiomyopathy (ACM).

RECENT FINDINGS

Recent developments highlight the capacity of AI to construct sophisticated models that accurately distinguish affected from non-affected cardiomyopathy patients. These AI-driven approaches not only offer precision in risk prediction and diagnostics but also enable early identification of individuals at high risk of developing cardiomyopathy, even before symptoms occur. These models have the potential to utilise diverse clinical input datasets such as electrocardiogram recordings, cardiac imaging, and other multi-modal genetic and omics datasets. Despite their current underrepresentation in literature, ACM diagnosis and risk prediction are expected to greatly benefit from AI computational capabilities, as has been the case for other cardiomyopathies. As AI-based models improve, larger and more complicated datasets can be combined. These more complex integrated datasets with larger sample sizes will contribute to further pathophysiological insights, better disease recognition, risk prediction, and improved patient outcomes.

Sudden Death in Obesity: Mechanisms and Management

In recent decades, the prevalence of obesity has increased significantly, leading to an epidemic at the global level. Obesity is associated with various metabolic alterations and increases the risk of cardiovascular disease. The most devastating manifestation of cardiovascular disease is sudden cardiac death (SCD), leading to substantial years of potential life lost worldwide. Obesity-related SCD is an increasingly important public health problem and warrants a specific investigative focus on improved risk stratification and prevention. In this review, we summarize the current evidence regarding management of SCD in obesity and discuss knowledge gaps as well as future directions in this field.

Decision-making processes behind seeking regular cardiac checkups for individuals with Marfan syndrome: A grounded theory study

Patients with Marfan syndrome (MFS) present with various symptoms, such as aortic aneurysm/dissection, tall stature, and lens deviation. Among them, acute aortic dissection is a complication that leads to sudden death. Some individuals with MFS are reluctant to see a cardiologist and discontinue regular checkups until they develop life-threatening complications. We conducted a grounded theory study to investigate how individuals with MFS decided whether to adhere to healthcare recommendations, specifically to attend cardiology appointments. The study recruited individuals with a clinical or genetic diagnosis of MFS from a Japanese university hospital and individuals from a support group. Semi-structured interviews were conducted with 28 consenting participants. In this study, we identified the decision-making processes of individuals with MFS concerning their cardiology visits. We extracted "perception of the gap between their health status and medical recommendations" as the central category. This decision-making process consisted of three parts: (A) the process by which an individual with MFS sees a cardiologist for the first time, (B) the process by which an individual with MFS keeps up with cardiology checkups, and (C) the process by which parents bring their children with MFS to the cardiologist. Individuals who learned of the possibility of MFS decided whether to adhere to medical recommendations depending on how they perceived the gap between their health status and the medical recommendations. In addition to medical information and treatment experience, adaptation to MFS, which changed through interactions with others, influenced the perception of the gap. This study suggests the role of genetic counseling and molecular genetic diagnosis as factors that may facilitate adaptation to MFS. The involvement of genetic counselors is important for helping individuals with MFS keep up with regular checkups while affirming their own experiences. These results provide insight into adherence to medical recommendations for individuals with MFS.

Genetic Biomarkers in Heart Failure: From Gene Panels to Polygenic Risk Scores

PURPOSE OF REVIEW

This review aims to provide a comprehensive overview of the current understanding of genetic markers associated with heart failure (HF) and its underlying causative diseases, such as cardiomyopathies. It highlights the relevance of genetic biomarkers in diagnosing HF, predicting prognosis, potentially identifying its preclinical stages and identifying targets to enable the implementation of individualized medicine approaches.

RECENT FINDINGS

The prevalence of HF is increasing due to an aging population but with greater access to disease-modifying therapies. Advanced diagnostic tools such as cardiac magnetic resonance, nuclear imaging, and AI-enabled diagnostic testing are now being utilized to further characterize HF patients. Additionally, the importance of genetic testing in HF diagnosis and management is increasingly being recognized. Genetic biomarkers, including single nucleotide polymorphisms (SNPs) and rare genetic variants, are emerging as crucial tools for diagnosing HF substrates, determining prognosis and increasingly directing therapy. These genetic insights are key to optimizing HF management and delivering personalized treatment tailored to individual patients. HF is a complex syndrome affecting millions globally, characterized by high mortality and significant economic burden. Understanding the underlying etiologies of HF is essential for improving management and clinical outcomes. Recent advances highlight the use of multimodal assessments, including AI-enabled diagnostics and genetic testing, to better characterize and manage HF. Genetic biomarkers are particularly promising in identifying preclinical HF stages and providing personalized treatment options. The genetic contribution to HF is heterogeneous, with both monogenic and polygenic bases playing a role. These developments underscore the shift towards personalized medicine in HF management.

Characterization and natural history of patients with LMNA-related dilated cardiomyopathy in the phase 3 REALM-DCM trial

AIMS

LMNA-related dilated cardiomyopathy (DCM) is a rare disease with an incompletely defined phenotype. The phase 3 REALM-DCM trial evaluated a potential disease-modifying therapy for LMNA-related DCM but was terminated due to futility without safety concern. This study utilized pooled data from REALM-DCM to descriptively characterize the phenotype and progression of LMNA-related DCM in a contemporary cohort of patients using common heart failure (HF) measures.

METHODS

REALM-DCM enrolled patients with stable LMNA-related DCM, an implanted cardioverter defibrillator or cardiac resynchronization therapy defibrillator, and New York Heart Association (NYHA) Class II/III HF symptoms.

RESULTS

Between 2018 and 2022, 77 patients took part in REALM-DCM. The median patient age was 53 years (range: 23-72), and 57% were male. Overall, 88% of patients had a pathogenic or likely pathogenic LMNA variant, and 12% had a variant of uncertain significance with a concordant phenotype. Among patients with confirmed sequencing, 55% had a missense variant. Atrial fibrillation was present in 60% of patients; 79% of all patients had NYHA Class II and 21% had NYHA Class III HF symptoms at baseline. Median (range) left ventricular ejection fraction (LVEF), 6 min walk test (6MWT) distance, Kansas City Cardiomyopathy Questionnaire Overall Summary (KCCQ-OS) score and N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration at baseline were 42% (23-62), 403 m (173-481), 67 (18-97) and 866 pg/mL (57-5248), respectively. LVEF, 6MWT distance and KCCQ-OS score were numerically lower in patients who had NYHA Class III versus II symptoms at baseline (LVEF: 38% vs. 43%; 6MWT distance: 326 vs. 413 m; and KCCQ-OS score: 43 vs. 70), whereas NT-proBNP concentration was higher (1216 vs. 799 pg/mL). Median follow-up was 73 weeks (range: 0.4-218; 73 in NYHA Class II and 75 in NYHA Class III). Patients displayed variable change from baseline in 6MWT, KCCQ-OS and NT-proBNP values during follow-up. Overall, 25% of patients experienced ventricular tachycardia, and 8% had ventricular fibrillation. Ten (13%) patients met the composite endpoint of worsening HF (adjudicated HF-related hospitalization or urgent care visit) or all-cause death; six had NYHA Class II and four had NYHA Class III at baseline. All-cause mortality occurred in 6 (8%) patients; three had NYHA Class II and three had NYHA Class III symptoms at baseline.

CONCLUSIONS

Findings confirm the significant morbidity and mortality associated with LMNA-related DCM despite the standard of care management. Typical measures of HF, including 6MWT distance, KCCQ-OS score and NT-proBNP concentration, were variable but correlated with NYHA class. An unmet treatment need remains among patients with LMNA-related DCM. NCT03439514.

Electrophysiological Phenotype-Genotype Study of Sustained Monomorphic Ventricular Tachycardia in Inherited, High Arrhythmic Risk, Left Ventricular Cardiomyopathy

BACKGROUND

Among inherited cardiomyopathies involving the left ventricle, whether dilated or not, certain genotypes carry a well-established arrhythmic risk, notably manifested as sustained monomorphic ventricular tachycardia (SMVT). Nonetheless, the precise localization and electrophysiological profile of this substrate remain undisclosed across different genotypes.

METHODS

Patients diagnosed with cardiomyopathy and left ventricle involvement due to high-risk genetic variants and SMVT treated by electrophysiological study were recruited from 18 European/US centers. Electrophysiological study, imaging, and outcomes data after ablation were assessed in relation to genotype.

RESULTS

Seventy-one patients were included (49.6 Q1-Q3 [40-60] years, 76% men). They were divided into 4 groups according to the affected protein: desmosomal (DSP, PKP2, DSG2, and DSC2), nuclear membrane (LMNA and TMEM43), cytoskeleton (FLNC and DES), and sarcoplasmic reticulum (PLN). Desmosomal genes, TMEM43, and PLN were associated with biventricular disease, while variants in LMNA and cytoskeleton genes had predominant left ventricle involvement (P=0.001). The location of the clinical-SMVT substrate was significantly different based on genotype (P=0.005). DSP and cytoskeleton genes presented SMVTs with right bundle branch block morphology, which origin was identified in the inferolateral segments of the left ventricle. The other desmosomal genes (PKP2 and DSG2), along with TMEM43, showed SMVTs with left bundle branch block morphology and predominantly right ventricular substrate. In contrast, LMNA substrate was mainly observed in the interventricular septum. During a median of 26 Q1-Q3 (10.6-65) months, 27% of patients experienced recurrences of clinical SMVT with differences between genotypes (log-rank 0.016). Nuclear membrane genes demonstrated the highest recurrence rate compared with desmosomal genes (hazard ratio, 4.56 [95% CI, 1.5-13.8]).

CONCLUSIONS

The anatomic substrate of SMVTs shows a strong correlation with the underlying genotype, electrocardiographic morphology, and recurrence rate. Particularly, patients with nuclear membrane gene variants have a significantly higher recurrence rate compared with those with desmosomal gene variants.

Impaired Atrial and Ventricular Strain Predicts Heart Failure in Arrhythmogenic Right Ventricular Cardiomyopathy

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) increases the risk of heart failure (HF) and arrhythmias. Speckle-tracking echocardiography (STE) detects myocardial dysfunction, but its predictive role for HF in this population remains unclear.

METHODS

Seventy-one patients with ARVC (age 43.7 ± 14.8 years, 53.5% male) without prevalent HF at baseline who were enrolled in the Johns Hopkins ARVC Registry were retrospectively included. Global strain (GS) and strain rate (SR) of the left ventricle (LV), right ventricle free wall (RVFW), left atrium (LA), and right atrium (RA) were measured by a blinded operator. Cox regression models assessed their association with incident HF.

RESULTS

Incident HF developed in 23 patients (age 49.3 ± 12.5 years, 52.2% male) during a median follow-up of 2.7 years. Decreases in strain were significantly associated with HF: LV peak global longitudinal systolic strain (GLS; hazard ratio [HR] 1.20, 95% confidence interval [CI] 1.06-1.35; P = 0.003), RVFW strain (HR 1.11, 95% CI 1.04-1.18; P = 0.003), LA GS (HR 1.05, 95% CI 1.00-1.09; P = 0.030), and RA GS (HR 1.07, 95% CI 1.03-1.12; P < 0.001). Associations for LV GLS, RVFW strain, and RA GS remained significant after adjusting for age and sex. Strain values frequently fell below established reference ranges. Any strain value (LV GLS, RVFW strain, LA GS, or RA GS) below the normal limit was associated with an 8-fold increase in HF (HR 8.43, 95% CI 1.97-36.02; P = 0.004), and each individual component below the normal threshold doubled the risk (HR 2.35, 95% CI 1.60-3.45; P < 0.001).

CONCLUSIONS

STE deformation abnormalities are associated with incident HF in ARVC patients. Echocardiographic strain may aid in identifying patients at risk of HF for closer follow-up and management.

Advances in Cardiac Imaging and Genetic Testing for Diagnosis and Risk Stratification in Cardiomyopathies: 2024 Update

Cardiomyopathies represent a diverse group of heart muscle diseases marked by structural and functional abnormalities that are not primarily caused by coronary artery disease. Recent advances in non-invasive imaging techniques, such as echocardiography, cardiac magnetic resonance, and computed tomography, have transformed diagnostic accuracy and risk stratification, reemphasizing the role of cardiac imaging in diagnosis, phenotyping, and management of these conditions. Genetic testing complements imaging by clarifying inheritance patterns, assessing sudden cardiac death risk, and informing therapeutic choices. Integrating imaging data, such as left ventricular wall thickness, fibrosis, and apical aneurysms, with genetic findings enhances decision-making for implantable cardioverter-defibrillators in high-risk patients. Emerging technologies like artificial intelligence, strain imaging, and molecular imaging, alongside genetic testing, hold the promise of further refining diagnosis and personalized treatment approaches. This article summarizes the current state and future perspectives of cardiac imaging and genetic testing for diagnosis and risk stratification in cardiomyopathies, offering practical insights for patients' management.

Prevalence and Correlates of Anti-DSG2 Antibodies in Arrhythmogenic Right Ventricular Cardiomyopathy and Myocarditis: Immunological Insights from a Multicenter Study

Background: Autoantibodies against Desmoglein-2 desmosomal protein (anti-DSG2-ab) were identified in Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) by Enzyme-Linked ImmunoSorbent Assay (ELISA); anti-intercalated disk autoantibodies (AIDAs) were identified in myocarditis and (ARVC) by indirect immunofluorescence (IFL). We aim to assess: (1) anti-DSG2-ab specificity in ARVC and myocarditis, (2) accuracy of anti-DSG2-ab detection by ELISA versus AIDA by IFL, and (3) clinical correlates of anti-DSG2-ab in ARVC. Methods: We included 77 patients with ARVC, 91 with myocarditis/dilated cardiomyopathy (DCM), 27 with systemic immune-mediated diseases, and 50 controls. Anti-heart antibodies (AHAs) and AIDAs were assessed by IFL, and anti-DSG2-ab by ELISA (assessed both by optical density, OD, and U/L). Receiving operator curve (ROC) analysis was used to assess ELISA diagnostic accuracy. Results: A relevant proportion (56%) of ARVC patients was anti-DSG2-ab-positive, with higher anti-DSG2-ab levels than controls. Anti-DSG2-ab titer was not different between ARVC and myocarditis/DCM patients (48% anti-DSG-ab positive). Frequency of anti-DSG2 positivity by ELISA was higher in AIDA-positive cases by IFL than AIDA-negative cases (p = 0.039 for OD, p = 0.023 for U/L). In ARVC, AIDA-positive patients were more likely to be AHA-positive (p < 0.001), had pre-syncope (p = 0.025), and abnormalities in cardiac rhythm (p = 0.03) than ARVC AIDA-negative patients, while anti-DSG2-ab positivity did not have clinical correlates. Conclusions: Anti-DG2-ab detection in ARVC and myocarditis/DCM reflects immune-mediated pathogenesis to desmosomal proteins. Higher frequency of anti-DSG2-ab positivity by ELISA by U/L was higher in AIDA-positive cases by IFL than AIDA-negative cases, in keeping with the hypothesis that DSG2 is one of AIDA autoantigens. In ARVC, AIDA status but not anti-DSG2-ab showed distinct clinical correlates, possibly reflecting a wider AIDA autoantigenic spectrum.

Clinical Features and Outcomes of Pediatric MYH7-Related Dilated Cardiomyopathy

BACKGROUND

Although genetic variants in MYH7 are the most frequent cause of pediatric genetic dilated cardiomyopathy (DCM), there are no studies available describing this entity. We sought to describe clinical features, analyze variant location, and explore predictors of bad prognosis in pediatric MYH7-related DCM.

METHODS AND RESULTS

We evaluated clinical records from 44 patients (24 men; median age at diagnosis, 0.54 [interquartile range, 0.01-10.8] years) with pathogenic/likely pathogenic variants in MYH7 diagnosed with DCM at pediatric age (<18 years) followed at 13 international centers. We also explored risk factors associated with a composite end point of end-stage heart failure defined as heart transplantation or heart failure-related death. Twenty-two patients (50%) were diagnosed at age <6 months, including 7 (16%) at birth. Left ventricular (LV) hypertrabeculation features were present in 15 (38%), particularly among patients with genetic variants in the head domain. After a median follow-up of 6.1 years (interquartile range, 1.9-13.4), 15 patients (36%) required a heart transplant (n=14) or died due to end-stage heart failure (n=1), 15 patients (36%) persisted with systolic dysfunction despite treatment, 12 (29%) had a significant increase in LV ejection fraction, and 2 were lost to follow-up. Overall, end-stage heart failure event rate was 25% at 5 years. New York Heart Association class III to IV (hazard ratio [HR], 7.67 [95% CI, 2.16-27.2]; P=0.002) and LV ejection fraction ≤35% (HR, 4.00 [95% CI, 1.11-14.4]; P=0.03) were the best predictors of bad prognosis.

CONCLUSIONS

Pediatric MYH7-related DCM is characterized by early onset, frequent LV hypertrabeculation, and poor prognosis. Advanced New York Heart Association class and low LV ejection fraction emerged as predictors of end-stage heart failure.

Navigating the Diagnostic and Management Challenges of Suspected Cardiac Amyloidosis in Resource-Limited Settings: Ethiopia Experience

This report discusses the diagnostic and therapeutic complexities encountered in resource-limited environments when assessing patients suspected of cardiac amyloidosis (CA). The study describes a case involving a patient who initially presented with heart failure symptoms and eventually received a CA diagnosis after 13 months and four primary physician visits, primarily based on discrepancies observed between electrocardiographic and echocardiographic findings, alongside elevated cardiac troponin levels. The case underscores the limited awareness of CA among primary healthcare providers in Ethiopia, contributing to a higher likelihood of misdiagnosis and inappropriate treatment approaches. Additionally, the report discusses the specific challenges associated with diagnosing and managing CA patients. It advocates for essential resources such as heightened clinical suspicion, proficiency in recognizing the characteristic electrocardiogram (ECG) and echocardiographic indicators of CA, and prompt referral to cardiologists.

Dilated Cardiomyopathy: A Genetic Journey from Past to Future

Dilated cardiomyopathy (DCM) is characterized by reduced systolic function and cardiac dilation. Cases without an identified secondary cause are classified as idiopathic dilated cardiomyopathy (IDC). Over the last 35 years, many cases of IDC have increasingly been recognized to be genetic in etiology with a core set of definitively causal genes in up to 40% of cases. While over 200 genes have been associated with DCM, the evidence supporting pathogenicity for most remains limited. Further, rapid advances in sequencing and bioinformatics have recently revealed a complex genetic spectrum ranging from monogenic to polygenic in DCM. These advances have also led to the discovery of causal and modifier genetic variants in secondary forms of DCM (e.g., alcohol-induced cardiomyopathy). Current guidelines recommend genetic counseling and screening, as well as endorsing a handful of genotype-specific therapies (e.g., device placement in LMNA cardiomyopathy). The future of genetics in DCM will likely involve polygenic risk scores, direct-to-consumer testing, and pharmacogenetics, requiring providers to have a thorough understanding of this rapidly developing field. Herein we outline three decades of genetics in DCM, summarize recent advances, and project possible future avenues for the field.

Genetic Testing Practices and Pathological Assessments in Patients With End-stage Heart Failure Undergoing Heart Transplantation and Left Ventricular Assist Device Use

BACKGROUND

Genetic cardiomyopathies (CMs) are increasingly recognized as causes of end-stage heart failure (ESHF). Identification of a genetic etiology in ESHF has important prognostic and family implications. However, genetic testing practices are understudied in patients with ESHF.

METHODS

This single-center, retrospective study included consecutive patients with ESHF who underwent heart transplantation (HT) or left ventricular assist device (LVAD) implantation between 2018 and 2023. Data, including genetic testing and pathology reports, were collected from the electronic medical records. Analyses of demographic and clinical characteristics were stratified by genetic-testing completion and the presence of clinically actionable variants. Logistic regression was performed to evaluate for associations between histology findings and genetic variants.

RESULTS

A total of 529 adult patients (mean age 57 years) were included in the study and were predominantly male (79%, 422/529) and non-white (61%, 322/529). Genetic testing was performed in 54% (196/360) of patients with either nonischemic or mixed CMs. A clinically actionable result was identified in 36% (70/196) of patients, of whom only 43% (30/70) had genetic counselor referrals. The most common genetic variants were TTN (32%, 24/75), MYBPC3 (13%, 10/75) and TTR (11%, 8/75). Clinically actionable variants were identified in patients with known heart failure precipitators such as alcohol use. In multivariable analysis, the presence of interstitial fibrosis, specifically diffuse, on pathology was significantly associated with a clinically actionable variant (aOR 2.29, 95% CI [1.08-4.86]; P = 0.03).

CONCLUSION

Patients with ESHF and with nonischemic or mixed CM who were undergoing advanced therapies had low uptakes of genetic services, including testing and counselors, despite high burdens of genetic disease. Pathology findings such as interstitial fibrosis may provide insight into genetic etiology. The underuse of services suggests a need for implementation strategies to improve uptake.

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.

2024 HRS expert consensus statement on arrhythmias in the athlete: Evaluation, treatment, and return to play

Youth and adult participation in sports continues to increase, and athletes may be diagnosed with potentially arrhythmogenic cardiac conditions. This international multidisciplinary document is intended to guide electrophysiologists, sports cardiologists, and associated health care team members in the diagnosis, treatment, and management of arrhythmic conditions in the athlete with the goal of facilitating return to sport and avoiding the harm caused by restriction. Expert, disease-specific risk assessment in the context of athlete symptoms and diagnoses is emphasized throughout the document. After appropriate risk assessment, management of arrhythmias geared toward return to play when possible is addressed. Other topics include shared decision-making and emergency action planning. The goal of this document is to provide evidence-based recommendations impacting all areas in the care of athletes with arrhythmic conditions. Areas in need of further study are also discussed.

Apicolateral bulge: A potential mimic of arrhythmogenic right ventricular cardiomyopathy in a professional athlete-A case report and literature review

Soccer is the most popular sport in the world, with over 265 million active players and approximately 0.05% professional players worldwide. The Fédération Internationale de Football Association (FIFA) has made preparticipation screening recommendations which involve electrocardiography and echocardiography being performed prior to international competition. The aim of preparticipation cardiovascular screening in young athletes is to detect asymptomatic individuals with cardiovascular disease at risk of sudden cardiac death (SCD). The incidence of SCD in young athletes (age≤ 35 years) is 0.6-3.6 in 100,000 persons/year, with most deaths due to cardiovascular causes. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is one of the leading causes of SCD in young athletes. It is a genetic disease characterized by progressive fibrofatty replacement of the myocardium with variable phenotypic expression. Exercise-induced cardiac remodeling in conjunction with extensive T-wave inversion raises concern for ARVC. This case report and literature review explores a potential mimic for ARVC, the role of cardiovascular screening in sport, and the use of a multimodality approach for risk stratification and management.

Contemporary diagnostic approach to arrhythmogenic cardiomyopathy: The three-step work-up

Arrhythmogenic Cardiomyopathy (ACM) is a cardiac disorder characterized by non-ischemic myocardial scarring, which may lead to ventricular electrical instability and systolic dysfunction. Diagnosing ACM is challenging as there is no single gold-standard test and a combination of criteria is required. The first diagnostic criteria were established in 1994 and revised in 2010, focusing primarily on right ventricular involvement. However, in 2019, an international expert report identified limitations of previous diagnostic scoring and developed the 2020 Padua criteria with also included criteria for diagnosis of left ventricular variants and introduced cardiac magnetic resonance tissue characterization findings for detection of left ventricular myocardial scar. These criteria were further refined and published in 2023 as the European Task Force criteria, gaining international recognition. This review provides an overview of the 20 years of progresses on the disease diagnostic from the original 1994 criteria to the most recent 2023 European criteria, highlighting the evolution into our understanding of the pathobiology and morpho-functional features of the disease.

A case report of a rare genetic mutation (LMNA-C.185G>C, p.Arg62Pro) associated with dilated cardiomyopathy in a Han Chinese child

Dilated cardiomyopathy (DCM) remains an enigmatic myocardial disorder characterized either by enlargement of either the left or right ventricle or both and reduced contractility, posing a significant burden on pediatric populations as a leading cause of cardiac-related mortality and morbidity. This paper presents a compelling case of DCM in a Han Chinese child whose genomic analysis unveiled a novel LMNA-C.185G>C (p.Arg62Pro) variant. Over a meticulous 3-year clinical follow-up, spanning ten outpatient consultations and hospital admissions since the initial diagnosis, the patient exhibited a progressive emergence of various cardiac conduction anomalies closely mirroring LMNA-associated phenotypes. Delving into a comprehensive review of the patient's 14-year medical journey and familial history, antecedent signs of muscular dystrophy (MD) predated DCM onset. Familial scrutiny revealed a lineage marred by muscular atrophy, with the patient's maternal grandmother having a history of muscular dystrophy and an episode of DCM, necessitating cardiac transplantation in the patient's uncle at age 37. This scenario illuminates the intricate interplay between LMNA-associated diseases and genetic predisposition. Timely identification of etiological triggers stands paramount in DCM management. Beyond conventional genetic scrutiny, leveraging novel serum biomarkers such as anti-heart muscle antibodies (AHA) remarkably enhanced diagnostic precision. Notably, personalized therapeutic interventions comprising prednisolone regimens and intravenous immunoglobulin infusions precipitated marked amelioration in heart failure symptoms and serum biomarker profiles. It is noteworthy to identify this novel genetic locus within the Han Chinese populace, underscoring the imperative of expanding the LMNA mutation repository within this demographic cohort. Early recognition of clinical manifestations and etiological cues in pediatric DCM heralds a paradigm shift in risk prognostication and individualized therapeutic interventions, underscoring the profound significance of precision medicine in combating rare familial cardiomyopathies.

Brazilian Guideline for Exercise Testing in Children and Adolescents - 2024

CLASSES OF RECOMMENDATION

LEVELS OF EVIDENCE

Hyperactivation of ATF4/TGF-β1 signaling contributes to the progressive cardiac fibrosis in Arrhythmogenic cardiomyopathy caused by DSG2 Variant

BACKGROUND

Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy characterized with progressive cardiac fibrosis and heart failure. However, the exact mechanism driving the progression of cardiac fibrosis and heart failure in ACM remains elusive. This study aims to investigate the underlying mechanisms of progressive cardiac fibrosis in ACM caused by newly identified Desmoglein-2 (DSG2) variation.

METHODS

We identified homozygous DSG2F531C variant in a family with 8 ACM patients using whole-exome sequencing and generated Dsg2F536C knock-in mice. Neonatal and adult mouse ventricular myocytes isolated from Dsg2F536C knock-in mice were used. We performed functional, transcriptomic and mass spectrometry analyses to evaluate the mechanisms of ACM caused by DSG2F531C variant.

RESULTS

All eight patients with ACM were homozygous for DSG2F531C variant. Dsg2F536C/F536C mice displayed cardiac enlargement, dysfunction, and progressive cardiac fibrosis in both ventricles. Mechanistic investigations revealed that the variant DSG2-F536C protein underwent misfolding, leading to its recognition by BiP within the endoplasmic reticulum, which triggered endoplasmic reticulum stress, activated the PERK-ATF4 signaling pathway and increased ATF4 levels in cardiomyocytes. Increased ATF4 facilitated the expression of TGF-β1 in cardiomyocytes, thereby activating cardiac fibroblasts through paracrine signaling and ultimately promoting cardiac fibrosis in Dsg2F536C/F536C mice. Notably, inhibition of the PERK-ATF4 signaling attenuated progressive cardiac fibrosis and cardiac systolic dysfunction in Dsg2F536C/F536C mice.

CONCLUSIONS

Hyperactivation of the ATF4/TGF-β1 signaling in cardiomyocytes emerges as a novel mechanism underlying progressive cardiac fibrosis in ACM. Targeting the ATF4/TGF-β1 signaling may be a novel therapeutic target for managing ACM.

Chronic phase subcutaneous implantable cardioverter defibrillator lead dislodgement in a patient with arrhythmogenic right ventricular cardiomyopathy

The subcutaneous implantable cardioverter defibrillator (S-ICD) is often used in young patients such as arrhythmogenic right ventricular cardiomyopathy (ARVC) and Brugada syndrome due to long-term lead durability issues. Although S-ICD lead dislodgement is rare, we encountered such an incident in a young ARVC patient during the chronic phase following the two-incision technique. Remote monitoring system is useful for early diagnosis of electrode movement (Graphical abstract image). When S-ICD lead dislodgement occurs in active young patients, lead revision using the three-incision technique may be an option.

The 2023 European Task Force Criteria for Diagnosis of Arrhythmogenic Cardiomyopathy: Historical Background and Review of Main Changes

Arrhythmogenic cardiomyopathy (ACM) is a cardiac disease featured by non-ischemic myocardial scarring linked to ventricular electrical instability. As there is no single gold-standard test, diagnosing ACM remains challenging and a combination of specific criteria is needed. The diagnostic criteria were first defined and widespread in 1994 and then revised in 2010, approaching and focusing primarily on right ventricular involvement without considering any kind of left ventricular variant or phenotype. Years later, in 2020, with the purpose of overcoming previous limitations, the Padua Criteria were introduced by an international expert report. The main novel elements were the introduction of specific criteria for left ventricular variants as well as the use of cardiac magnetic resonance for tissue characterization and scar detection. The last modifications and refinement of these criteria were published at the end of 2023 as the European Task Force criteria, by a "head-quarter" of ACM international experts, proving the emerging relevance of this condition besides its difficult diagnosis. In this review, emphasizing the progress in understanding the aetiology of the cardiomyopathy, an analysis of the new criteria is presented. The introduction of the term "scarring/arrhythmogenic cardiomyopathy" sets an important milestone in this field, underlying how non-ischemic myocardial scarring-typical of ACM-and arrhythmic susceptibility could be the main pillars of numerous different phenotypic variants regardless of etiology.

Evaluation of the 2021 ESC recommendations for family screening in hereditary transthyretin cardiac amyloidosis

AIMS

The 2021 European Society of Cardiology (ESC) screening recommendations for individuals carrying a pathogenic transthyretin amyloidosis variant (ATTRv) are based on expert opinion. We aimed to (i) determine the penetrance of ATTRv cardiomyopathy (ATTRv-CM) at baseline; (ii) examine the value of serial evaluation; and (iii) establish the yield of first-line diagnostic tests (i.e. electrocardiogram, echocardiogram, and laboratory tests) as per 2021 ESC position statement.

METHODS AND RESULTS

We included 159 relatives (median age 55.6 [43.2-65.9] years, 52% male) at risk for ATTRv-CM from 10 centres. The primary endpoint, ATTRv-CM diagnosis, was defined as the presence of (i) cardiac tracer uptake in bone scintigraphy; or (ii) transthyretin-positive cardiac biopsy. The secondary endpoint was a composite of heart failure (New York Heart Association class ≥II) and pacemaker-requiring conduction disorders. At baseline, 40/159 (25%) relatives were diagnosed with ATTRv-CM. Of those, 20 (50%) met the secondary endpoint. Indication to screen (≤10 years prior to predicted disease onset and absence of extracardiac amyloidosis) had an excellent negative predictive value (97%). Other pre-screening predictors for ATTRv-CM were infrequently identified variants and male sex. Importantly, 13% of relatives with ATTRv-CM did not show any signs of cardiac involvement on first-line diagnostic tests. The yield of serial evaluation (n = 41 relatives; follow-up 3.1 [2.2-5.2] years) at 3-year interval was 9.4%.

CONCLUSIONS

Screening according to the 2021 ESC position statement performs well in daily clinical practice. Clinicians should adhere to repeating bone scintigraphy after 3 years, as progressing to ATTRv-CM without signs of ATTRv-CM on first-line diagnostic tests or symptoms is common.

The differentiation of the competitive athlete with physiologic cardiac remodeling from the athlete with cardiomyopathy

There are currently 5 million active high school, collegiate, professional, and master athletes in the United States. Regular intense exercise by these athletes can promote structural, electrical and functional remodeling of the heart, which is termed the "athlete's heart." In addition, regular intense exercise can lead to pathological adaptions that promote or worsen cardiac disease. Many of the athletes in the United States seek medical care. Consequently, physicians must be aware of the normal cardiac anatomy and physiology of the athlete, the differentiation of the normal athlete heart from the athlete with cardiomyopathy, and the contemporary care of the athlete with a cardiomyopathy. In athletes with persistent cardiovascular symptoms, investigations should include a detailed history and physical examination, an ECG, a transthoracic echocardiogram, and in athletes in whom the diagnosis is uncertain, a maximal exercise stress test or a continuous ECG recording, and cardiac magnetic resonance imaging or cardiac computed tomography angiography when definition of the coronary anatomy or characterization of the aorta and the aortic great vessels is indicated. This article discusses the differentiation of the normal athlete with physiologic cardiac remodeling from the athlete with hypertrophic, dilated or arrhythmogenic ventricular cardiomyopathy (ACM). The ECG changes in trained athletes that are considered normal, borderline, or abnormal are listed. In addition, the normal echocardiographic measurements for athletes who consistently participate in endurance, power, combined or heterogeneous sports are enumerated and discussed. Algorithms are listed that are useful in the diagnosis of trained athletes with borderline or abnormal echocardiographic measurements suggestive of cardiomyopathies along with the major and minor criteria for the diagnosis of ACM in athletes. Thereafter, the treatment of athletes with hypertrophic, dilated, and arrhythmogenic right ventricular cardiomyopathies are reviewed. The distinction between physiologic changes and pathologic changes in the hearts of athletes has important therapeutic and prognostic implications. Failure by the physician to correctly diagnose an athlete with hypertrophic cardiomyopathy, dilated cardiomyopathy, or ACM, can lead to the sudden cardiac arrest and death of the athlete during training or sports competition. Conversely, an incorrect diagnosis by a physician of cardiac pathology in a normal athlete can lead to an unnecessary restriction of athlete training and competition with resultant significant emotional, psychological, financial, and long-term health consequences in the athlete.

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 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.

Improved diagnosis of arrhythmogenic right ventricular cardiomyopathy using electrocardiographic deep learning

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare genetic heart disease associated with life-threatening ventricular arrhythmias. Diagnosis of ARVC is based on the 2010 Task Force Criteria (TFC), application of which often requires clinical expertise at specialized centers.

OBJECTIVE

The purpose of this study was to develop and validate an electrocardiogram (ECG) deep learning (DL) tool for ARVC diagnosis.

METHODS

ECGs of patients referred for ARVC evaluation were used to develop (n = 551 [80.1%]) and test (n = 137 [19.9%]) an ECG-DL model for prediction of TFC-defined ARVC diagnosis. The ARVC ECG-DL model was externally validated in a cohort of patients with pathogenic or likely pathogenic (P/LP) ARVC gene variants identified through the Geisinger MyCode Community Health Initiative (N = 167).

RESULTS

Of 688 patients evaluated at Johns Hopkins Hospital (JHH) (57.3% male, mean age 40.2 years), 329 (47.8%) were diagnosed with ARVC. Although ARVC diagnosis made by referring cardiologist ECG interpretation was unreliable (c-statistic 0.53; confidence interval [CI] 0.52-0.53), ECG-DL discrimination in the hold-out testing cohort was excellent (0.87; 0.86-0.89) and compared favorably to that of ECG interpretation by an ARVC expert (0.85; 0.84-0.86). In the Geisinger cohort, prevalence of ARVC was lower (n = 17 [10.2%]), but ECG-DL-based identification of ARVC phenotype remained reliable (0.80; 0.77-0.83). Discrimination was further increased when ECG-DL predictions were combined with non-ECG-derived TFC in the JHH testing (c-statistic 0.940; 95% CI 0.933-0.948) and Geisinger validation (0.897; 95% CI 0.883-0.912) cohorts.

CONCLUSION

ECG-DL augments diagnosis of ARVC to the level of an ARVC expert and can differentiate true ARVC diagnosis from phenotype-mimics and at-risk family members/genotype-positive individuals.

Myoclonic Epilepsy With Ragged Red Fiber Cardiomyopathy: A Case Report and Brief Review of Literature

Myoclonic epilepsy with ragged red fibers (MERRF) is a rare mitochondrial disease that can affect various organs, including the heart. We present a case report and brief review of the literature with the aim of exploring the progression of cardiac involvement in patients with MERRF. A 65-year-old male with a history of MERRF, first diagnosed at age 55 with interventricular septum hypertrophy, presented with acute heart failure. The patient's clinical course over 10 years demonstrated a transition from a hypertrophic to a dilated cardiomyopathy phenotype, contrasting earlier findings suggesting rapid progression in younger patients. Despite optimized heart failure therapy, the patient experienced a progressive decline in ventricular function with frequent ventricular arrhythmias, ultimately requiring implantable cardioverter-defibrillator (ICD) placement. This case supports the hypothesis that MERRF-related cardiac involvement may progress more slowly when onset occurs later in life, leading to a gradual transition from hypertrophic to dilated cardiomyopathy. An accurate cardiac diagnostic workup is essential for early detection and timely intervention in such patients. The natural history of cardiac involvement in MERRF can vary significantly based on the age of onset, highlighting the importance of personalized diagnostic and therapeutic approaches in managing this rare mitochondrial disorder.

Left ventricular reverse remodelling as a promising strategy for resolving left ventricular thrombus

AIMS

Recent years, several studies have suggested that abnormal baseline left ventricular (LV) function and structure are associated with left ventricular thrombus (LVT) formation. Despite this, most studies have given less attention to the potential role of left ventricular reverse remodelling (LVRR), that is, the improvement of LV function and structure, in resolving LVT. In this study, we aim to investigate the clinical characteristics, prognosis, and LVT resolution in patients with LVRR.

METHODS AND RESULTS

This is a retrospective study conducted at The First Affiliated Hospital of Dalian Medical University. Our cohort consists of patients diagnosed with LVT between 1 November 2015 and 31 May 2020. Enrolled patients were categorized into two groups: LVRR and Failure of LVRR. The primary endpoints included LVT resolution and embolic events. A total of 84 patients were included in the study, with 59 patients in the LVRR group and 25 patients in the Failure of LVRR group. In our study, patients in the LVRR group experienced higher incidence of LVT resolution and a lower risk of embolic events. Multivariate logistic analysis revealed that Failure of LVRR was the only independent negative predictor for LVT resolution and positive predictor for embolic events.

CONCLUSIONS

Patients with LVRR experience higher incidence of LVT resolution and have lower risk of embolic events, highlighting the significance of identifying and mitigating risk factors that contribute to abnormal LV function and structure in management of patients with LVT.

Prognostic value of right ventricular trabecular complexity in patients with arrhythmogenic cardiomyopathy

OBJECTIVES

The present study aimed to investigate the incremental prognostic value of the right ventricular fractal dimension (FD), a novel marker of myocardial trabecular complexity by cardiac magnetic resonance (CMR) in patients with arrhythmogenic cardiomyopathy (ACM).

METHODS

Consecutive patients with ACM undergoing CMR were followed up for major cardiac events, including sudden cardiac death, aborted cardiac arrest, and appropriate implantable cardioverter defibrillator intervention. Prognosis prediction was compared by Cox regression analysis. We established a multivariable model supplemented with RV FD and evaluated its discrimination by Harrell's C-statistic. We compared the category-free, continuous net reclassification improvement (cNRI) and integrated discrimination index (IDI) before and after the addition of FD.

RESULTS

A total of 105 patients were prospectively included from three centers and followed up for a median of 60 (48, 66) months; experienced 36 major cardiac events were recorded. Trabecular FD displayed a strong unadjusted association with major cardiac events (p < 0.05). In the multivariable Cox regression analysis, RV maximal apical FD maintained an independent association with major cardiac events (hazard ratio, 1.31 (1.11-1.55), p < 0.002). The Hosmer-Lemeshow goodness of fit test displayed good fit (X2 = 0.68, p = 0.99). Diagnostic performance was significantly improved after the addition of RV maximal apical FD to the multivariable baseline model, and the continuous net reclassification improvement increased 21% (p = 0.001), and the integrated discrimination index improved 16% (p = 0.045).

CONCLUSIONS

In patients with ACM, CMR-assessed myocardial trabecular complexity was independently correlated with adverse cardiovascular events and provided incremental prognostic value.

CLINICAL RELEVANCE STATEMENT

The application of FD values for assessing RV myocardial trabeculae may become an accessible and promising parameter in monitoring and early diagnosis of risk factors for adverse cardiovascular events in patients with ACM.

KEY POINTS

• Ventricular trabecular morphology, a novel quantitative marker by CMR, has been explored for the first time to determine the severity of ACM. • Patients with higher maximal apical fractal dimension of RV displayed significantly higher cumulative incidence of major cardiac events. • RV maximal apical FD was independently associated with major cardiac events and provided incremental prognostic value in patients with ACM.