Arrhythmogenic right ventricular dysplasia: a United States experience

Endurance Training Provokes Arrhythmogenic Right Ventricular Cardiomyopathy Phenotype in Heterozygous Desmoglein-2 Mutants: Alleviation by Preload Reduction

Desmoglein-2 mutations are detected in 5-10% of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Endurance training accelerates the development of the ARVC phenotype, leading to earlier arrhythmic events. Homozygous Dsg2 mutant mice develop a severe ARVC-like phenotype. The phenotype of heterozygous mutant (Dsg2mt/wt) or haploinsufficient (Dsg20/wt) mice is still not well understood. To assess the effects of age and endurance swim training, we studied cardiac morphology and function in sedentary one-year-old Dsg2mt/wt and Dsg20/wt mice and in young Dsg2mt/wt mice exposed to endurance swim training. Cardiac structure was only occasionally affected in aged Dsg20/wt and Dsg2mt/wt mice manifesting as small fibrotic foci and displacement of Connexin 43. Endurance swim training increased the right ventricular (RV) diameter and decreased RV function in Dsg2mt/wt mice but not in wild types. Dsg2mt/wt hearts showed increased ventricular activation times and pacing-induced ventricular arrhythmia without obvious fibrosis or inflammation. Preload-reducing therapy during training prevented RV enlargement and alleviated the electrophysiological phenotype. Taken together, endurance swim training induced features of ARVC in young adult Dsg2mt/wt mice. Prolonged ventricular activation times in the hearts of trained Dsg2mt/wt mice are therefore a potential mechanism for increased arrhythmia risk. Preload-reducing therapy prevented training-induced ARVC phenotype pointing to beneficial treatment options in human patients.

AAV9:PKP2 improves heart function and survival in a Pkp2-deficient mouse model of arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a familial cardiac disease associated with ventricular arrhythmias and an increased risk of sudden cardiac death. Currently, there are no approved treatments that address the underlying genetic cause of this disease, representing a significant unmet need. Mutations in Plakophilin-2 (PKP2), encoding a desmosomal protein, account for approximately 40% of ARVC cases and result in reduced gene expression.

METHODS

Our goal is to examine the feasibility and the efficacy of adeno-associated virus 9 (AAV9)-mediated restoration of PKP2 expression in a cardiac specific knock-out mouse model of Pkp2.

RESULTS

We show that a single dose of AAV9:PKP2 gene delivery prevents disease development before the onset of cardiomyopathy and attenuates disease progression after overt cardiomyopathy. Restoration of PKP2 expression leads to a significant extension of lifespan by restoring cellular structures of desmosomes and gap junctions, preventing or halting decline in left ventricular ejection fraction, preventing or reversing dilation of the right ventricle, ameliorating ventricular arrhythmia event frequency and severity, and preventing adverse fibrotic remodeling. RNA sequencing analyses show that restoration of PKP2 expression leads to highly coordinated and durable correction of PKP2-associated transcriptional networks beyond desmosomes, revealing a broad spectrum of biological perturbances behind ARVC disease etiology.

CONCLUSIONS

We identify fundamental mechanisms of PKP2-associated ARVC beyond disruption of desmosome function. The observed PKP2 dose-function relationship indicates that cardiac-selective AAV9:PKP2 gene therapy may be a promising therapeutic approach to treat ARVC patients with PKP2 mutations.

Management Strategies in Arrhythmogenic Cardiomyopathy across the Spectrum of Ventricular Involvement

Improved disease recognition through family screening and increased life expectancy with appropriate sudden cardiac death prevention has increased the burden of heart failure in arrhythmogenic cardiomyopathy (ACM). Heart failure management guidelines are well established but primarily focus on left ventricle function. A significant proportion of patients with ACM have predominant or isolated right ventricle (RV) dysfunction. Management of RV dysfunction in ACM lacks evidence but requires special considerations across the spectrum of heart failure regarding the initial diagnosis, subsequent management, monitoring for progression, and end-stage disease management. In this review, we discuss the unique aspects of heart failure management in ACM with a special focus on RV dysfunction.

Arrhythmogenic Cardiomyopathy: from Preclinical Models to Genotype-phenotype Correlation and Pathophysiology

Arrhythmogenic cardiomyopathy (ACM) is a hereditary myocardial disease characterized by the replacement of the ventricular myocardium with fibrous fatty deposits. ACM is usually inherited in an autosomal dominant pattern with variable penetrance and expressivity, which is mainly related to ventricular tachyarrhythmia and sudden cardiac death (SCD). Importantly, significant progress has been made in determining the genetic background of ACM due to the development of new techniques for genetic analysis. The exact molecular pathomechanism of ACM, however, is not completely clear and the genotype-phenotype correlations have not been fully elucidated, which are useful to predict the prognosis and treatment of ACM patients. Different gene-targeted and transgenic animal models, human-induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) models, and heterologous expression systems have been developed. Here, this review aims to summarize preclinical ACM models and platforms promoting our understanding of the pathogenesis of ACM and assess their value in elucidating the ACM genotype-phenotype relationship.

The Many Faces of Arrhythmogenic Cardiomyopathy: An Overview

Arrhythmogenic cardiomyopathy (AC) is a disease that involves electromechanical uncoupling of cardiomyocytes. This leads to characteristic histologic changes that ultimately lead to the arrhythmogenic clinical features of the disease. Initially thought to affect the right ventricle predominantly, more recent data show that it can affect both the ventricles or the left ventricle alone. Throughout the recent era, diagnostic modalities and criteria for AC have continued to evolve and our understanding of its clinical features in different age groups as well as the genotype to the phenotype correlations have improved. In this review, we set out to detail the epidemiology, etiologies, presentations, evaluation, and management of AC across the age continuum.

Predicting ventricular tachycardia circuits in patients with arrhythmogenic right ventricular cardiomyopathy using genotype-specific heart digital twins

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic cardiac disease that leads to ventricular tachycardia (VT), a life-threatening heart rhythm disorder. Treating ARVC remains challenging due to the complex underlying arrhythmogenic mechanisms, which involve structural and electrophysiological (EP) remodeling. Here, we developed a novel genotype-specific heart digital twin (Geno-DT) approach to investigate the role of pathophysiological remodeling in sustaining VT reentrant circuits and to predict the VT circuits in ARVC patients of different genotypes. This approach integrates the patient's disease-induced structural remodeling reconstructed from contrast-enhanced magnetic-resonance imaging and genotype-specific cellular EP properties. In our retrospective study of 16 ARVC patients with two genotypes: plakophilin-2 (PKP2, n = 8) and gene-elusive (GE, n = 8), we found that Geno-DT accurately and non-invasively predicted the VT circuit locations for both genotypes (with 100%, 94%, 96% sensitivity, specificity, and accuracy for GE patient group, and 86%, 90%, 89% sensitivity, specificity, and accuracy for PKP2 patient group), when compared to VT circuit locations identified during clinical EP studies. Moreover, our results revealed that the underlying VT mechanisms differ among ARVC genotypes. We determined that in GE patients, fibrotic remodeling is the primary contributor to VT circuits, while in PKP2 patients, slowed conduction velocity and altered restitution properties of cardiac tissue, in addition to the structural substrate, are directly responsible for the formation of VT circuits. Our novel Geno-DT approach has the potential to augment therapeutic precision in the clinical setting and lead to more personalized treatment strategies in ARVC.

Arrhythmogenic Cardiomyopathy: Evolving Diagnostic Criteria and Insight from Cardiac Magnetic Resonance Imaging

Arrhythmogenic cardiomyopathy (ACM) is an umbrella term encompassing a wide variety of overlapping hereditary and nonhereditary disorders that can result in malignant ventricular arrhythmias and sudden cardiac death. Cardiac MRI plays a critical role in accurate diagnosis of various ACM entities and is increasingly showing promise in risk stratification that can further guide management particularly in decisions regarding use of implantable cardioverter defibrillator. Genotyping plays an important role in cascade testing but challenges remain due to incomplete penetrance and wide phenotypic variability of ACM as well as the presence of gene-elusive cases.

Clinical and Genetic Characteristics of Arrhythmogenic Right Ventricular Cardiomyopathy Patients: A Single-Center Experience

Background

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited progressive cardiomyopathy. We aimed to define the long-term clinical outcome and genetic characteristics of patients and family members with positive genetic tests for ARVC in a single tertiary care cardiac center in Saudi Arabia.

Methods

We enrolled 46 subjects in the study, including 23 index-patients (probands) with ARVC based on the revised 2010 ARVC Task Force Criteria (TFC) and 23 family members who underwent a genetic test for the ARVC between 2016 and 2020.

Results

Of the probands, 17 (73.9%) were males with a mean age at presentation of 24.95 ± 13.9 years (7 to 55 years). Predominant symptoms were palpitations in 14 patients (60.9%), and syncope in 10 patients (43.47%). Sustained ventricular tachycardia (VT) was documented in 12 patients (52.2%). The mean left ventricular ejection fraction (LVEF) by echocardiogram was 52.81±6.311% (30-55%), and the mean right ventricular ejection fraction (RVEF) by cardiac MRI was 41.3±11.37% (23-64%). Implantable cardioverter-defibrillator (ICD) implantation was performed in 17 patients (73.9%), and over a mean follow-up of 13.65 ± 6.83 years, appropriate ICD therapy was noted in 12 patients (52.2%). Genetic variants were identified in 33 subjects (71.7%), 16 patients and 17 family members, with the most common variant of plakophilin 2 (PKP2) in 27 subjects (81.8%).

Conclusions

ARVC occurs during early adulthood in Saudi patients. It is associated with a significant arrhythmia burden in these patients. The PKP2 gene is the most common gene defect in Saudi patients, consistent with what is observed in other nations. We reported in this study two novel variants in PKP2 and desmocollin 2 (DSC2) genes. Genetic counseling is needed to include all first-degree family members for early diagnosis and management of the disease in our country.

Phenotyping heart failure by genetics and associated conditions

Heart failure is a highly heterogeneous disease, and genetic testing may allow phenotypic distinctions that are incremental to those obtainable from imaging. Advances in genetic testing have allowed for the identification of deleterious variants in patients with specific heart failure phenotypes (dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and hypertrophic cardiomyopathy), and many of these have specific treatment implications. The diagnostic yield of genetic testing in heart failure is modest, and many rare variants are associated with incomplete penetrance and variable expressivity. Environmental factors and co-morbidities have a large role in the heterogeneity of the heart failure phenotype. Future endeavours should concentrate on the cumulative impact of genetic polymorphisms in the development of heart failure.

Monitoring of Myocardial Involvement in Early Arrhythmogenic Right Ventricular Cardiomyopathy Across the Age Spectrum

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by fibrofatty replacement of primarily the right ventricular myocardium, a substrate for life-threatening ventricular arrhythmias (VAs). Repeated cardiac imaging of at-risk relatives is important for early disease detection. However, it is not known whether screening should be age-tailored.

OBJECTIVES

The goal of this study was to assess the need for age-tailoring of follow-up protocols in early ARVC by evaluating myocardial disease progression in different age groups.

METHODS

We divided patients with early-stage ARVC and genotype-positive relatives without overt structural disease and VA at first evaluation into 3 groups: age <30 years, 30 to 50 years, and ≥50 years. Longitudinal biventricular deformation characteristics were used to monitor disease progression. To link deformation abnormalities to underlying myocardial disease substrates, Digital Twins were created using an imaging-based computational modeling framework.

RESULTS

We included 313 echocardiographic assessments from 82 subjects (57% female, age 39 ± 17 years, 10% probands) during 6.7 ± 3.3 years of follow-up. Left ventricular global longitudinal strain slightly deteriorated similarly in all age groups (0.1%-point per year [95% CI: 0.05-0.15]). Disease progression in all age groups was more pronounced in the right ventricular lateral wall, expressed by worsening in longitudinal strain (0.6%-point per year [95% CI: 0.46-0.70]) and local differences in myocardial contractility, compliance, and activation delay in the Digital Twin. Six patients experienced VA during follow-up.

CONCLUSIONS

Disease progression was similar in all age groups, and sustained VA also occurred in patients aged >50 years without overt ARVC phenotype at first evaluation. Unlike recommended by current guidelines, our study suggests that follow-up of ARVC patients and relatives should not stop at older age.

Predicting Ventricular Tachycardia Circuits in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy using Genotype-specific Heart Digital Twins

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic cardiac disease that leads to ventricular tachycardia (VT), a life-threatening heart rhythm disorder. Treating ARVC remains challenging due to the complex underlying arrhythmogenic mechanisms, which involve structural and electrophysiological (EP) remodeling. Here, we developed a novel genotype-specific heart digital twin (Geno-DT) approach to investigate the role of pathophysiological remodeling in sustaining VT reentrant circuits and to predict the VT circuits in ARVC patients of different genotypes. This approach integrates the patient's disease-induced structural remodeling reconstructed from contrast-enhanced magnetic-resonance imaging and genotype-specific cellular EP properties. In our retrospective study of 16 ARVC patients with two genotypes: plakophilin-2 (PKP2, n = 8) and gene-elusive (GE, n = 8), we found that Geno-DT accurately and non-invasively predicted the VT circuit locations for both genotypes (with 100%, 94%, 96% sensitivity, specificity, and accuracy for GE patient group, and 86%, 90%, 89% sensitivity, specificity, and accuracy for PKP2 patient group), when compared to VT circuit locations identified during clinical EP studies. Moreover, our results revealed that the underlying VT mechanisms differ among ARVC genotypes. We determined that in GE patients, fibrotic remodeling is the primary contributor to VT circuits, while in PKP2 patients, slowed conduction velocity and altered restitution properties of cardiac tissue, in addition to the structural substrate, are directly responsible for the formation of VT circuits. Our novel Geno-DT approach has the potential to augment therapeutic precision in the clinical setting and lead to more personalized treatment strategies in ARVC.

Diagnosis and management of arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disorder of the myocardium that can lead to ventricular arrhythmia and sudden cardiac death. The condition has been identified as a significant cause of arrhythmic death among young people and athletes, therefore, early recognition of the disease by emergency clinicians is critical to prevent subsequent death. The diagnosis of ARVC can be very challenging and requires a systematic approach. This publication reviews the pathophysiology, classification, clinical presentations, and appropriate approach to diagnosis and management of ARVC.

Varied Presentation of Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C): A Case Series

Arrhythmogenic right ventricular dysplasia (ARVD) is a genetically predisposed form of cardiomyopathy that mainly affects young individuals resulting in fatal ventricular arrhythmias leading to sudden cardiac death. ARVD has 50% of cases that involve both the right ventricle (RV) and left ventricle (LV), but only a small number of cases involve an isolated left ventricle. In this case series, five patients (four males and one female) with a diagnosis of ARVD presented to our center with varied clinical presentations across a wide range of age groups. The MRI of all five cases showed dilated right atrium (RA)/RV with right ventricular free wall dyskinesia. Two-dimensional (2D) MRI showed aneurysmal outpouching with diffuse free wall enhancement. Automated implantable cardioverter defibrillator (AICD) was implanted uneventfully in all five patients, and the patients were discharged with oral medications such as low-dose diuretics, beta-blockers, spironolactone, angiotensin-converting enzymes (ACE) inhibitors, amiodarone, and anxiolytics. Until now, the patients were doing well on follow-up visits. The therapeutic management of patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) has evolved over the years and continues to be an important challenge. To further improve risk stratification and treatment of patients, more information is needed on natural history, long-term prognosis, and risk assessment. Special attention should be focused on the identification of patients who would benefit from implantable cardioverter-defibrillator (ICD) implantation in comparison to pharmacological and other nonpharmacological approaches.

Impact of Amiodarone Therapy on the Ablation Outcome of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy

(1) Background: Catheter ablation (CA) is an accepted treatment option for drug-refractory ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). This study investigates the effect of amiodarone on ablation outcomes in ARVC. (2) Methods: The study enrolled patients with ARVC undergoing CA of sustained VT. In all patients, substrate modification was performed to achieve non-inducible VT. The patients were categorized into two groups according to whether they had used amiodarone before CA. Baseline and electrophysiological characteristics, substrate, and outcomes were compared. (3) Results: A total of 72 ARVC patients were studied, including 29 (40.3%) "off" amiodarone and 43 (56.7%) "on" amiodarone. The scar area was similar between the two groups. Patients "off" amiodarone had smaller endocardial and epicardial areas with abnormal electrograms. Twenty of 43 patients (47.5%) "on" amiodarone discontinued it within 3 months after CA. During a mean follow-up period of 43.2 ± 29.5 months, higher VT recurrence was observed in patients "on" amiodarone. Patients "on" amiodarone who discontinued amiodarone after CA had a lower recurrence than those without. (4) Conclusions: Patients with ARVC "on" amiodarone before CA had distinct substrate characteristics and worse ablation outcomes than patients "off" amiodarone, especially in those who had used amiodarone continuously.

Analysis of digitalized ECG signals based on artificial intelligence and spectral analysis methods specialized in ARVC

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease that appears between the second and forth decade of a patient's life, being responsible for 20% of sudden cardiac deaths before the age of 35. The effective and punctual diagnosis of this disease based on electrocardiograms (ECGs) could have a vital role in reducing premature cardiovascular mortality. In our analysis, we first outline the digitalization process of paper-based ECG signals enhanced by a spatial filter aiming to eliminate dark regions in the dataset's images that do not correspond to ECG waveform, producing undesirable noise. Next, we propose the utilization of a low-complexity convolutional neural network for the detection of an arrhythmogenic heart disease, that has not been studied through the usage of deep learning methodology to date, achieving high classification accuracy, namely 99.98% training and 98.6% testing accuracy, on a disease the major identification criterion of which are infinitesimal millivolt variations in the ECG's morphology, in contrast with other arrhythmogenic abnormalities. Finally, by performing spectral analysis we investigate significant differentiations in the field of frequencies between normal ECGs and ECGs corresponding to patients suffering from ARVC. In 16 out of the 18 frequencies where we encounter statistically significant differentiations, the normal ECGs are characterized by greater normalized amplitudes compared to the abnormal ones. The overall research carried out in this article highlights the importance of integrating mathematical methods into the examination and effective diagnosis of various diseases, aiming to a substantial contribution to their successful treatment.

Continuous-flow left ventricular assist device treatment for arrhythmogenic right ventricular cardiomyopathy complicated by advanced biventricular failure - University of Tokyo experiences

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyocyte disease characterized by intractable ventricular arrhythmia in the majority of affected patients. Some of these patients also manifest right ventricular dysfunction and heart failure symptoms. Fatal ventricular arrhythmia has been the primary cause of death in ARVC patients. However, increased early recognition of ARVC and improvement in arrhythmic risk stratification and treatment have dramatically improved survival. A small proportion of the patients are further complicated by left ventricular impairment at the late phase in addition to right heart failure, for whom only heart transplantation is the last resort. Because of the relative rarity of ARVC with biventricular failure, no consensus or guideline has been reported on how to effectively support these patients with a mechanical circulatory device. Herein, four ARVC patients with biventricular failure were presented who were successfully bridged to heart transplantation after long-term support by isolated continuous-flow LVAD.

Sudden death in young athletes: Is it preventable?

Sudden death in young athletes is a rare but always dramatic condition. Unlike all other rare diseases, the estimate of its real incidence is made complex not only because of the uncertain number of correctly identified cases (numerator) but also because of the uncertain estimation of the real number of the reference population, the athletes (denominator). New elements of complexity are also emerging with regard to prevention. The current two pillars of prevention are pre-participation screening (proactive strategy) and promoting use / access to the automated external defibrillator (reactive strategy). The standardization of procedures implemented over the past two decades for pre-participation screening can now allow us to assess the impact of this approach. The result is complex to evaluate. While screening may allow the identification of conditions potentially associated with SDA, and therefore the adoption of specific treatments, in about 0.4% of screened subjects, a single study investigated the yield in terms of mortality showing a positive predictive value of 4.7% with 25% sensitivity. Conversely, the reactive strategy appears considerably effective, due to the widespread use of the automated external defibrillators in sports facilities, calling for a homogeneous implementation worldwide. On a broader perspective, the vast attention devoted to SDA prevention in the world of sports represents a major driver for transfer of a reactive prevention strategy to the general population.

Arrhythmogenic Cardiomyopathy: A Review of a Rare Case of Biventricular Phenotype

Arrhythmogenic cardiomyopathy is a rare hereditary structural heart disease, with various phenotypes, which mostly affects the right ventricle of the heart, resulting in fibrofatty replacement of the heart muscles and a proclivity to create spontaneous malignant cardiac arrhythmias that may lead to sudden death. Most previous reports were noted on young people. We report a case of its biventricular phenotype in a 61-year-old heavy truck driver who has a current medical history of diabetes mellitus and smoking and was incidentally diagnosed based on the Padua criteria after presenting to the hospital with complaints of lightheadedness and syncope. He eventually had an implantable cardioverter defibrillator, hence preventing death. We were able to correctly diagnose the case and prevent sudden cardiac death by instituting the necessary management.

Value of 3D echocardiography in the diagnosis of arrhythmogenic right ventricular cardiomyopathy

Aims

The 2010 Task Force Criteria (TFC) require that both right ventricular (RV) regional wall-motion abnormalities (WMA) and specific RV size cut-offs be met in order to fulfil one of the major criterion for arrhythmogenic right ventricular cardiomyopathy (ARVC) diagnosis. Currently, 2D echocardiography (2DE) and cardiovascular magnetic resonance imaging (cMRI) are used to determine if these criteria are met. Little is known about the diagnostic value of 3D echocardiography (3DE) in ARVC. The aim of this study was to determine whether a combination of 2DE-3DE is non-inferior to the currently used 2DE-cMRI combination in the diagnosis of patients with ARVC.

Methods and results

Thirty-nine individuals (47±15 years) with suspected ARVC underwent evaluation of the RV with cMRI, 2DE, and 3DE. 3DE and cMRI were independently used to obtain RV volumes, ejection fraction (EF) and determine the presence of segmental RV WMA. Studies were blindly classified as meeting criteria for ARVC in accordance with the 2010 TFC. Kappa statistics were used to test the concordance between 2DE–cMRI and 2DE–3DE approaches. Using the 2DE–cMRI approach, 3/39 were not affected, 5/39 possible, 8/39 borderline, and 23/39 definite ARVC. The proposed 2DE–3DE approach yielded 5/39 not affected, 7/39 possible, 8/39 borderline, and 19/39 definite diagnoses. The two approaches were highly concordant (k = 0.71; 95% confidence interval: 0.44–0.84). Although 3DE underestimated RV volumes in comparison with cMRI, interfering, in some instances with the fulfilment of a major criterion, it was able to identify more RV WMA (28/39) than 2DE (11/39), with a detection-rate comparable to cMRI (33/39) highlighting a unique advantage.

Conclusion

The combination of 2DE–3DE for ARVC diagnosis is comparable to the conventional 2DE–cMRI approach. 3DE should be performed in all suspected ARVC patients to aide in the detection of WMA.

Family History and Warning Symptoms Precede Sudden Cardiac Death in Arrhythmogenic Right Ventricular Cardiomyopathy (from a Nationwide Study in Sweden)

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiac disease explaining about 4% of sudden cardiac death (SCD) cases in the young in Sweden. This study aimed to describe the circumstances preceding SCD in all victims <35 years of age who received an autopsy-confirmed diagnosis of ARVC from January 1, 2000, to December 31, 2010, in Sweden (n = 22). Data on demographics, medical and family history, circumstances of death, and anatomopathological findings were collected from several compulsory national health registries, clinical records, family interviews, and autopsy reports. Registry-based data were compared with age-matched, gender-matched, and geographically-matched population controls. During the 6 months preceding SCD, 15 cases (68%) had experienced symptoms of cardiac origin, mainly syncope or presyncope (54%) and chest discomfort (27%). A total of 8 cases (36%) had sought medical care because of cardiac symptoms. The occurrence of hospital visits was significantly increased in cases compared with controls (odds ratio 4.62 [1.35 to 15.8]). A total of 10 cases (45%) had a family history of SCD. The most common activity at the time of death was exercise (41%). A complete cardiac investigation was seldom performed; only 1 case was diagnosed with ARVC before death. In conclusion, in this nationwide study, we observed a high prevalence of symptoms of cardiac origin, healthcare use, and family history of SCD preceding SCD in the young caused by ARVC. Increased awareness of these warning signals in younger patients is critical to improving risk stratification and early disease detection.

Arrhythmogenic Right Ventricular Dysplasia (ARVD) With Protein Plakophilin-2 Mutation

Arrhythmogenic right ventricular dysplasia (ARVD) is a heart muscle disease that predominantly affects the right ventricle; however, biventricular involvement is increasingly being recognized. Fibrofatty tissue replacement is a central feature of ARVD. The majority of the identified genes, including protein plakophilin-2 (PKP-2), involved in cell-to-cell adhesion, can be seen in most genetic cases. Clinically, affected individuals present with palpitations, syncope, or sudden death due to ventricular arrhythmias, such as ventricular tachycardia (VT) or fibrillation, with symptomatic heart failure usually only in later stages.

In this study, we present a male patient with ARVD who underwent a genetic test that revealed ARVD with PKP-2 mutation after multiple admissions for heart failure and arrhythmias. He ultimately underwent orthotopic heart transplantation (OHT). Early detection is important for further management, risk stratification, and reduced hospitalization in patients with ARVD.

Clinical Significance of Structural Remodeling Concerning Substrate Characteristics and Outcomes in Arrhythmogenic Right Ventricular Cardiomyopathy

Background

The substrate and ablation outcome in arrhythmogenic right ventricular cardiomyopathy (ARVC) with or without right ventricular (RV) dysfunction is unclear.

Objective

We aimed to investigate ablation outcome and substrate in ARVC patients with or without RV dysfunction.

Methods

We retrospectively studied ARVC patients with (group 1) or without RV dysfunction (group 2) undergoing substrate mapping/ablation. Baseline characteristics and electrophysiological features were compared. The RV was divided into 7 prespecified segments. The scarred segment was defined as more than 50% of the area with bipolar scar. A multivariate regression analysis was performed to predict the risk of ventricular tachycardia (VT) recurrence.

Results

A total of 106 patients were enrolled (57 in group 1 and 49 in group 2). There were more men (73.7% vs 32.7%, P < .05) in group 1 than group 2. Group 1 patients demonstrated larger abnormal substrate in both the endocardium (13.4 ± 14.7 cm² vs 7.8 ± 5.4 cm², P = .014) and in the epicardium (40.3 ± 27.7 cm² vs 14.2 ± 12.6 cm², P = .002) and had more scar in the inferior portion/tricuspid valve (TV) than group 2 patients. Twenty-five patients had recurrences of VT/ventricular fibrillation. After multivariate analysis, the presence of a superior TV scar in the endocardium predicted the recurrence in patients with sustained VT.

Conclusion

The presence of RV dysfunction was associated with a larger abnormal substrate in the endocardium and epicardium of the RV. A scar involving the inferior portion and TV is associated with RV dysfunction. Scarring in the superior TV of the endocardium can predict recurrence despite catheter ablation.

Heart transplantation outcomes in arrhythmogenic right ventricular cardiomyopathy: a contemporary national analysis

Aims

Heart failure is an increasingly recognized later stage manifestation of arrhythmogenic right ventricular cardiomyopathy (ARVC) that can require heart transplantation (HT) to appropriately treat. We aimed to study contemporary ARVC HT outcomes in a national registry.

Methods and results

The United Network for Organ Sharing registry was queried for HT recipients from 1/1994 through 2/2020. ARVC patients were compared with non‐ARVC dilated, restrictive, and hypertrophic cardiomyopathy HT patients (HT for ischaemic and valvular disease was excluded from analysis). Post‐HT survival was assessed using Kaplan–Meier estimates. A total of 189 of 252 (75%) waitlisted ARVC patients (median age 48 years, 65% male) underwent HT, representing 0.3% of the total 65 559 HT during the study time period. Annual frequency of HT for ARVC increased significantly over time. ARVC patients had less diabetes (5% vs. 17%, P < 0.001), less cigarette use (15% vs. 23%, P < 0.001), lower pulmonary artery and pulmonary capillary wedge pressures, and lower cardiac output than the 33 659 non‐ARVC patients (P < 0.001). Ventricular assist device use was significantly lower in ARVC patients (8% vs. 32%, P < 0.001); 1 and 5 year post‐HT survival was 97% and 93% for ARVC vs. 95% and 82% for non‐ARVC HT recipients (P < 0.001). On adjusted multivariable Cox regression, ARVC had decreased risk of post‐HT death compared with non‐ARVC aetiologies (hazard ratio 0.48, 95% confidence interval 0.28–0.82, P = 0.008). Patients with ARVC also had lower risk of death or graft failure than non‐ARVC patients (hazard ratio 0.51, 95% confidence interval 0.32–0.81, P = 0.004).

Conclusions

In the largest series of HT in ARVC, we found that HT is increasingly performed in ARVC, with higher survival compared with other cardiomyopathy aetiologies. The right ventricular predominant pathophysiology may require unique considerations for heart failure management, including HT.

Sudden cardiac death in cardiomyopathies: acting upon "acceptable" risk in the personalized medicine era

Patients with cardiomyopathies are confronted with the risk of sudden cardiac death (SCD) throughout their lifetime. Despite the fact that SCD is relatively rare, prognostic stratification is an integral part of physician-patient discussion, with the goal of risk modification and prevention. The current approach is based on a concept of "acceptable risk." However, there are intrinsic problems with an algorithm-based approach to risk management, magnified by the absence of robust evidence underlying clinical decision support tools, which can make high- versus low-risk classifications arbitrary. Strategies aimed at risk reduction range from selecting patients for an implantable cardioverter defibrillator (ICD) to disqualification from competitive sports. These clinical options, especially when implying the use of finite financial resources, are often delivered from the physician's perspective citing decision-making algorithms. When the burden of intervention-related risks or financial costs is deemed higher than an "acceptable risk" of SCD, the patient's perspective may not be appropriately considered. Designating a numeric threshold of "acceptable risk" has ethical implications. One could reasonably ask "acceptable to whom?" In an era when individual choice and autonomy are pillars of the physician-patient relationship, the subjective aspects of perceived risk should be acknowledged and be part of shared decision-making. This is particularly true when the lack of a strong scientific evidence base makes a dichotomous algorithm-driven approach suboptimal for unmitigated translation to clinical practice.

Repolarisation abnormalities unmasked with a 252-lead BSM system in patients with ARVC and healthy Gene Carriers

Background: Diagnosing arrhythmogenic right ventricular cardiomyopathy (ARVC) at an early stage can be challenging even after ECG recording and a combination of several imaging techniques. The purpose of this study was to explore if a body surface mapping (BSM) system with 252‐leads could identify repolarization abnormalities and thereby diagnose early stages of ARVC.

Methods: ARVC patients, gene carriers without signs of ARVC and controls underwent a 12‐lead resting ECG, signal‐averaged ECG, echocardiography, 24‐hours Holter monitoring, and BSM with electrocardiographic imaging (ECGI). All 252‐leads, divided into four quadrants of the vest, were analyzed regarding concordances between T wave polarity and QRS main vector.

Results: Of 40 patients included there were 12 ARVC patients, 20 gene carriers, and 8 controls. The ARVC patients had two different repolarization patterns, one with more pronounced negative T waves at the lower left panel and another with mixed changes that clearly differed from the controls, all of whom had a normal 12 lead ECGs and consistent repolarization patterns on their BSM recordings. The patterns observed in ARVC patients were also present in 5/20 (25%) gene carriers, three of whom had normal resting ECG. A novel repolarization index successfully detected all ARVC patients and 88% of gene carriers with pathologic repolarization pattern.

Conclusions: The finding that abnormal repolarization patterns could be unmasked by BSM in 25% of healthy gene carriers, suggests that it may potentially be a useful tool for identifying early manifestations of ARVC. Further and larger studies are warranted to assess its diagnostic accuracy.

Arrhythmogenic right ventricular cardiomyopathy in the pediatric population

PURPOSE OF REVIEW

Review the current state of the art of arrhythmogenic right ventricular cardiomyopathy (ARVC) diagnosis and risk stratification in the pediatric population.

RECENT FINDINGS

ARVC is an inherited cardiomyopathy characterized by progressive myocyte loss and fibrofatty replacement of predominantly the right ventricle and high risk of ventricular arrhythmias and sudden cardiac death (SCD). ARVC is one of the leading causes of arrhythmic cardiac arrest in young people. Early diagnosis and accurate risk assessment are challenging, especially in children who often exhibit little to no phenotype, even if genotype positive. Multimodal imaging provides more detailed assessment of the right ventricle and has been shown in pediatric patients to identify earlier preclinical disease expression. Identification of patients with ARVC allows the clinician to intervene early with appropriate exercise restrictions, even if genotype positive only without phenotypic expression. Emphasis should be placed on stratifying the patient's risk of ventricular arrhythmias and SCD.

SUMMARY

ARVC is a challenging diagnosis to make in adolescents who often do not exhibit clinical symptoms. Newer multimodal imaging techniques and improvements in genetic testing and biomarkers should help improve early diagnosis. Exercise restriction for children with ARVC has been shown to reduce disease advancement and decreases the risk of a life-threatening event.

Heart Failure in Patients with Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is a rare inherited cardiomyopathy characterized as fibro-fatty replacement, and a common cause for sudden cardiac death in young athletes. Development of heart failure (HF) has been an under-recognized complication of ACM for a long time. The current clinical management guidelines for HF in ACM progression have nowadays been updated. Thus, a comprehensive review for this great achievement in our understanding of HF in ACM is necessary. In this review, we aim to describe the research progress on epidemiology, clinical characteristics, risk stratification and therapeutics of HF in ACM.

Anatomical-MRI Correlations in Adults and Children with Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare disease in which the right ventricular myocardium is replaced by islands of fibro-adipose tissue. Therefore, ventricular re-entry circuits can occur, predisposing the patient to ventricular tachyarrhythmias, as well as dilation of the right ventricle that eventually leads to heart failure. Although it is a rare disease with low prevalence in Europe and the United States, many patients are addressed disproportionately for cardiac magnetic resonance imaging (MRI). The most severe consequence of this condition is sudden cardiac death at a young age due to untreated cardiac arrhythmias. The purpose of this paper is to revise the magnetic resonance characteristics of ARVC, including the segmental contraction abnormalities, fatty tissue replacement, decrease of the ejection fraction, and the global RV dilation. Herein, we also present several recent improvements of the 2010 Task Force criteria that are not included within the ARVC diagnosis guidelines. In our opinion, these features will be considered in a future Task Force Consensus.

Arrhythmogenic Right Ventricular Cardiomyopathy Diagnosis

Arrhythmogenic right ventricular cardiomyopathy, formerly called "arrhythmogenic right ventricular dysplasia," is an under-recognized clinical entity characterized by ventricular arrhythmias and a characteristic ventricular pathology. Diagnosis is often difficult due to the nonspecific nature of the disease and the broad spectrum of phenotypic variations. Therefore, consensus diagnostic criteria have been developed which combine electrocardiographic, echocardiographic, cardiac magnetic resonance imaging and histologic criteria. In 1994, an international task force first proposed the major and minor diagnostic criteria of arrhythmogenic right ventricular cardiomyopathy based on family history, arrhythmias, electrocardiographic abnormalities, tissue characterization, and structural and functional right ventricular abnormalities. In 2010, the task force criteria were revised to include quantitative abnormalities. These diagnostic modalities and the most recent task force criteria are discussed in this review.

Sporadic and rapidly progressive arrhythmogenic right ventricular cardiomyopathy in a 12-year-old boy who was diagnosed with epilepsy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is one of the leading causes of sudden cardiac death amongst young people and athletes. In this genetic disease, arrhythmia and fibro-fatty changes in the right ventricular myocardium are the main characteristics of the disease. Here, we report a case of ARVC in a 12-year-old boy who was previously diagnosed with epilepsy, the patient's condition manifested sporadically and was complicated by rapid progression, and unfortunate fatal deterioration after admission into the pediatric emergency room due to fatigue, dizziness and palpitation. A diagnosis of ARVC was established, even though a family history was absent. Due to possible rapid deterioration, as described in this case, we recommend immediate primary and secondary prevention of arrhythmias in these patients, and to take in consideration of the potential risks of using sodium valproate in these patients.

Right ventricular dysplasia in the elderly: a case report from autopsy

Right ventricular dysplasia (RVD) is a rare disease of the heart that primarily affects the right ventricle. It is a clinical and pathological entity that presents classically with palpitations, syncope, or even sudden death. It presents rarely in the elderly. Where sudden death is the first and only presentation, an autopsy is required to make the diagnosis. However, the pathomorphological features of RVD can easily be overlooked or missed at autopsy. We report the case of a 68-year-old male with the past medical history of hypertension, gout and inflammatory bowel syndrome. He was admitted on account of difficulty in breathing, abdominal swelling and reduced urination. Physical examination revealed hypertension with cardiac murmurs, widespread crepitations, distended abdomen and lower limb oedema. Provisional diagnoses of acute-on-chronic kidney disease and congestive cardiac failure secondary to hypertensive heart disease, precipitated by probable gastrointestinal infection were made. While on admission, he had an episode of syncope. Electrocardiogram revealed bigeminy and bradycardic sinus rhythm with unifocal ventricular premature contraction. He died on the 8^th week of admission. Autopsy revealed an enlarged heart weighing 600gm; there was thinning of the apical aspect of the right ventricular wall with subtotal fibrofatty replacement. Microscopic examination revealed a transmural replacement of cardiac myocytes by fibroadipose tissue extending inwards, in the most parts, from the epicardium to the endocardial surface. Our aim is to increase the awareness of these pathomorphological features among anatomic/forensic pathologists.

Actionable secondary findings in arrhythmogenic right ventricle cardiomyopathy genes: impact and challenge of genetic counseling

Background

Comprehensive genetic analysis yields in a higher diagnostic rate but also in a higher number of secondary findings (SF). American College of Medical Genetics and Genomics (ACMG) published a list of 59 actionable genes for which disease causing sequence variants are recommended to be reported as SF including 27 genes linked to inherited cardiovascular disease (CVD) such as arrhythmia syndromes, cardiomyopathies and vascular and connective tissue disorders. One of the selected conditions represented in the actionable gene list is the arrhythmogenic right ventricle cardiomyopathy (ARVC), an inherited heart muscle disease with a particularly high risk of sudden cardiac death (SCD). Since clinical symptoms are frequently absent before SCD, a genetic finding is a promising option for early diagnosis and possible intervention. However, the variant interpretation and the decision to return a SF is still challenging.

Methods

To determine the frequency of medically actionable SF linked to CVD we analyzed data of 6,605 individuals who underwent high throughput sequencing for noncardiac diagnostic requests. In particular, we critically assessed and classified the variants in the ARVC genes: DSC2, DSG2, DSP, PKP2 and TMEM43 and compared our findings with the population-based genome Aggregation Database (gnomAD) and ARVC-afflicted individuals listed in ClinVar and ARVC database.

Results

1% (69/6,605) of tested individuals carried pathogenic SF in one of the 27 genes linked to CVD, of them 13 individuals (0.2%) carried a pathogenic SF in a ARVC gene. Overall, 582 rare variants were identified in all five ARVC genes, 96% of the variants were missense variants and 4% putative LoF variants (pLoF): frameshift, start/stop-gain/loss, splice-site. Finally, we selected 13 of the 24 pLoF variants as pathogenic SF by careful data interpretation.

Conclusions

Since SF in actionable ARVC genes can allow early detection and prevention of disease and SCD, detected variant must undergo rigorous clinical and laboratory evaluation before it can be described as pathogenic and returned to patients. Returning a SF to a patient should be interdisciplinary, it needs genetic counselling and clinicians experienced in inherited heart disease.

Clinical significance of J waves with respect to substrate characteristics and ablation outcomes in patients with arrhythmogenic right ventricular cardiomyopathy

AIMS

J-wave syndrome in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) has been linked to an increased risk of ventricular arrhythmia. We investigated the significance of J waves with respect to substrate manifestations and ablation outcomes in patients with ARVC.

METHODS AND RESULTS

Forty-five patients with ARVC undergoing endocardial/epicardial mapping/ablation were studied. Patients were classified into two groups: 13 (28.9%) and 32 (71.1%) patients with and without J waves, respectively. The baseline characteristics, electrophysiological features, ventricular substrate, and recurrent ventricular tachycardia/fibrillation (VT/VF) were compared. Among the 13 patients with J waves, only the inferior J wave was observed. More ARVC patients with J waves fulfilled the major criteria of ventricular arrhythmias (76.9% vs. 21.9%, P = 0.003). Similar endocardial and epicardial substrate characteristics were observed between the two groups. However, patients with J waves had longer epicardial total activation time than those without (224.7 ± 29.9 vs. 200.8 ± 21.9 ms, P = 0.005). Concordance of latest endo/epicardial activation sites was observed in 29 (90.6%) patients without J waves and in none among those with J waves (P < 0.001). Complete elimination of endocardial/epicardial abnormal potentials resulted in the disappearance of the J wave in 8 of 13 (61.5%) patients. The VT/VF recurrences were not different between ARVC patients with and without J waves.

CONCLUSION

The presence of J waves was associated with the discordance of endocardial/epicardial activation pattern in terms of transmural depolarization discrepancy in patients with ARVC.

Cardiac sarcoidosis masquerading as arrhythmogenic right ventricular cardiomyopathy: a case report

Background

Cardiac sarcoidosis (CS) and arrhythmogenic right ventricular cardiomyopathy (ARVC) are rare causes of ventricular arrhythmias and are associated with sudden cardiac death. Differentiation between both is important for proper management.

Case summary

We present a 56-year-old man with sudden cardiac arrest and was diagnosed to have ARVC based on cardiac magnetic resonance imaging (MRI). He developed gradually worsening shortness of breath over the next 1 year. CS was unmasked after a cardiac positron emission tomography (PET). Patient was treated with methotrexate. A repeat cardiac PET scan showed improvement.

Discussion

The distinction between ARVC and CS is challenging. Both these entities have a patchy involvement and can have similar presentations. ARVC has a predominant right heart involvement. It is diagnosed with the help of an MRI, which shows regional right ventricular wall motion abnormality. These findings can have an overlap with CS. It is important to note that, even though sarcoidosis is a pathologic diagnosis, cardiac biopsy is rarely done owing to its patchy involvement. Cardiac PET scan has a high sensitivity and specificity to diagnose this entity. Once diagnosis is made, patients should be treated with immunosuppressants and should be closely followed. Repeat imaging should be considered at intervals to monitor disease progression. This case highlights the importance of multimodality imaging and tissue diagnosis to unmask the diagnosis of CS, a treatable infiltrative disorder which shares features with a potentially untreatable ARVC.

Cardiovascular Magnetic Resonance Imaging and Heart Failure

Purpose of Review

The purpose of this review is to summarize the application of cardiac magnetic resonance (CMR) in the diagnostic and prognostic evaluation of patients with heart failure (HF).

Recent Findings

CMR is an important non-invasive imaging modality in the assessment of ventricular volumes and function and in the analysis of myocardial tissue characteristics. The information derived from CMR provides a comprehensive evaluation of HF. Its unique ability of tissue characterization not only helps to reveal the underlying etiologies of HF but also offers incremental prognostic information.

Summary

CMR is a useful non-invasive tool for the diagnosis and assessment of prognosis in patients suffering from heart failure.

Clinical Findings and Diagnostic Yield of Arrhythmogenic Cardiomyopathy Through Genomic Screening of Pathogenic or Likely Pathogenic Desmosome Gene Variants

BACKGROUND

Genomic screening holds great promise for presymptomatic identification of hidden disease, and prevention of dramatic events, including sudden cardiac death associated with arrhythmogenic cardiomyopathy (ACM). Herein, we present findings from clinical follow-up of carriers of ACM-associated pathogenic/likely pathogenic desmosome variants ascertained through genomic screening.

METHODS

Of 64 548 eligible participants in Geisinger MyCode Genomic Screening and Counseling program (2015-present), 92 individuals (0.14%) identified with pathogenic/likely pathogenic desmosome variants by clinical laboratory testing were referred for evaluation. We reviewed preresult medical history, patient-reported family history, and diagnostic testing results to assess both arrhythmogenic right ventricular cardiomyopathy and left-dominant ACM.

RESULTS

One carrier had a prior diagnosis of dilated cardiomyopathy with arrhythmia; no other related diagnoses or diagnostic family history criteria were reported. Fifty-nine carriers (64%) had diagnostic testing in follow-up. Excluding the variant, 21/59 carriers satisfied at least one arrhythmogenic right ventricular cardiomyopathy task force criterion, 11 (52%) of whom harbored DSP variants, but only 5 exhibited multiple criteria. Six (10%) carriers demonstrated evidence of left-dominant ACM, including high rates of atypical late gadolinium enhancement by magnetic resonance imaging and nonsustained ventricular tachycardia. Two individuals received new cardiomyopathy diagnoses and received defibrillators for primary prevention.

CONCLUSIONS

Genomic screening for pathogenic/likely pathogenic variants in desmosome genes can uncover both left- and right-dominant ACM. Findings of overt cardiomyopathy were limited but were most common in DSP-variant carriers and notably absent in PKP2-variant carriers. Consideration of the pathogenic/likely pathogenic variant as a major criterion for diagnosis is inappropriate in the setting of genomic screening.

Electrocardiographic features of arrhythmogenic right ventricular cardiomyopathy in school-aged children

It can be difficult to distinguish children with early-stage arrhythmogenic right ventricular cardiomyopathy (ARVC) from those with benign premature ventricular contraction (PVC). We retrospectively evaluated six school-aged children with ARVC and compared with those of 20 with benign PVC. The median age at initial presentation was 11.4 and 10.2 years in ARVC and benign PVC, respectively. None of the ARVC patients fulfilled the diagnostic criteria of ARVC at initial presentation. At ARVC diagnosis, the treadmill exercise test and Holter monitoring showed provoked PVC during exercise and pleomorphic PVC in all ARVC cases, respectively. During the observation period, terminal activation duration (TAD) was prolonged in all ARVC patients. In addition, ΔTAD (5.5 [3-10] ms) were significantly longer than those with benign PVC (p < 0.001). A new notched S-wave in V1 appeared in four (67%) ARVC patients, who had myocardial abnormalities in the right ventricle, and in zero benign PVC. Our electrocardiographic findings, such as provoked PVC during exercise, pleomorphic PVC, prolonged TAD, and a new notched S-wave in V1 could contribute to the early detection of ARVC in school-aged children.

Two Novel Variants in Genes of Arrhythmogenic Right Ventricular Cardiomyopathy - a Case Report

SUMMARY BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable cardiomyopathy, characterized by fibrofatty replacement of myocytes in the right ventricular, left ventricular or both ventricles. It is caused by pathogenic variants of genes encoding desmosomal (JUP, DSP, PKP2, DSG2, DSC2) and non-desmosomal proteins, and is one of the most common causes of sudden cardiac death in young athletes. Therefore, early identification, correct prevention and treatment can prevent adverse outcomes.

CASE REPORT

Our case presents a 65-years-old man with recurrent ventricular tachycardia. The ischemic cause was the first to rule out. Echocardiography revealed right ventricular structural and functional abnormalities. After suspicion of ARVC, magnetic resonance imaging was performed showing reduced right ventricular ejection fraction with local aneurysms, structural changes ir the right and left myocardium. Subsequently performed genetic testing identified a novel ARVC likely pathogenic variant in DSC2 gene and variant of uncertain significance in RYR2 gene.

CONCLUSIONS

Diagnostic evaluation of ARVC is challenging and requires multidisciplinary team collaboration. Further functional tests for elucidation of the clinical significance of the two novel variants of ARVC-associated genes could be suggested.

Sex Differences in Right Ventricular Dysfunction: Insights From the Bench to Bedside

There are inherent distinctions in right ventricular (RV) performance based on sex as females have better RV function than males. These differences are magnified and have very important prognostic implications in two RV-centric diseases, pulmonary hypertension (PH), and arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). In both PH and ARVC/D, RV dysfunction results in poor patient outcomes. However, there are no currently approved therapies specifically targeting the failing RV, an important unmet need for these two life-threatening disorders. In this review, we highlight human data demonstrating divergent RV phenotypes in healthy, PH, and ARVC/D patients based on sex. Furthermore, we discuss the links between estrogen (the female predominant sex hormone), testosterone (the male predominant sex hormone), and dehydroepiandrosterone (a precursor hormone for multiple sex hormones in males and females) and RV function in both disorders. To provide potential mechanistic insights into sex differences in RV function, we review data that investigate how sex hormones combat or contribute to pathophysiological changes in the RV. Finally, we highlight the ongoing clinical trials in pulmonary arterial hypertension targeting estrogen and dehydroepiandrosterone signaling. Hopefully, a greater understanding of the factors that promote superior RV function in females will lead to novel therapeutic approaches to combat RV dysfunction in PH and ARVC/D.

Evidence-based management of arrhythmogenic right ventricular cardiomyopathy in pregnancy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disorder resulting in fibrofatty replacement of the myocardium. Genetic mutations in genes encoding for desmosome proteins result in a ventricular myocardium prone to arrhythmias and heart failure. Although ARVC is known for a few decades, most of the outcomes in pregnancy are reported recently. Pregnancy leads to significant physiological changes with excess mechanical stress on the myocardium. All the retrospective studies suggest that pregnancy is well tolerated in these patients despite the high risk of arrhythmias and heart failure. Our review focuses on the most up-to-date evidence on the management of ARVC patients during the antepartum and postpartum period.

Potential role of imaging markers in predicting future disease expression of arrhythmogenic cardiomyopathy

Aim: To evaluate the predictive accuracy of trabecular hypertrophy/derangement and late gadolinium enhancement in predicting diagnosis of arrhythmogenic cardiomyopathy (AC). Materials & methods: Fifty-nine suspected AC patients were evaluated. To evaluate the ability of these markers to detect patients fulfilling definite diagnosis at 4-year follow-up, sensitivity (Se), specificity (Sp), positive and negative predictive value (PPV and NPV) and predictive accuracy (PA) were calculated. Results: Presence of trabecular hypertrophy/derangement showed high NPV, while late gadolinium enhancement at cardiac MRI high Sp, NPV and PA. Their combination with symptoms and/or revised Task Force Criteria showed a high Sp, NPV and PA for definitive diagnosis during follow-up. Conclusion: In suspected AC patients, the absence of these markers allows to identify those with lower risk of disease progression.

Right ventricular dysfunction and long-term risk of death

Sudden cardiac death (SCD), or sudden loss of life-sustaining systemic and cerebral perfusion, is most often due to left ventricular (LV) dysfunction secondary to ischemic or structural cardiac disease or channelopathies. Degeneration of sinus rhythm into ventricular tachycardia and ultimately ventricular fibrillation is the final common pathway for most heart failure patients. Right ventricular (RV) dysfunction is recognized as an independent contributor to worsening heart failure. There is emerging evidence that RV dysfunction may also be an independent predictor of SCD. This review examines the role of RV dysfunction on modifying long term risk of SCD, and explores possible mechanisms that may underlie SCD. The RV has unique anatomy and physiology compared to the LV. Subsequently, we begin with a review of cardiac embryology, focusing on the chambers, valves, coronary arteries, and cardiac conduction system to understand the origins of RV dysfunction. Static and dynamic physiology of the RV is contrasted with that of the LV. Particular emphasis is placed on ventriculo-arterial coupling, mechanical cardiac constraint, and ventricular interdependence. The epidemiology of SCD is briefly reviewed to highlight how causes of SCD are age-specific. In turn, the age-specific causes of RV dysfunction are presented, including those which predominate in childhood and adolescence [arrhythmogenic RV dysplasia (ARVD) and hypertrophic cardiomyopathy (HCM)] and older adulthood (cardiac ischemia, chronic congestive heart failure and post-capillary pulmonary hypertension, and pulmonary hypertension). There is a clear need for additional studies on the independent contribution of RV dysfunction to overall functional capacity, SCD-associated mortality, and non-SCD-associated mortality. Discovery would be aided by the development of prospective cohorts with excellent RV phenotyping, coupled with deeper biologic measurements linking mechanisms to clinically relevant outcomes.

Epidemiology of the inherited cardiomyopathies

In the absence of contemporary, population-based epidemiological studies, estimates of the incidence and prevalence of the inherited cardiomyopathies have been derived from screening studies, most often of young adult populations, to assess cardiovascular risk or to detect the presence of disease in athletes or military recruits. The global estimates for hypertrophic cardiomyopathy (1/500 individuals), dilated cardiomyopathy (1/250) and arrhythmogenic right ventricular cardiomyopathy (1/5,000) are probably conservative given that only individuals who fulfil diagnostic criteria would have been included. This caveat is highly relevant because a substantial minority or even a majority of individuals who carry disease-causing genetic variants and are at risk of disease complications have incomplete and/or late-onset disease expression. The genetic literature on cardiomyopathy, which is often focused on the identification of genetic variants, has been biased in favour of pedigrees with higher penetrance. In clinical practice, an abnormal electrocardiogram with normal or non-diagnostic imaging results is a common finding for the sarcomere variants that cause hypertrophic cardiomyopathy, the titin and sarcomere variants that cause dilated cardiomyopathy and the desmosomal variants that cause either arrhythmogenic right ventricular cardiomyopathy or dilated cardiomyopathy. Therefore, defining the genetic epidemiology is also challenging given the overlapping phenotypes, incomplete and age-related expression, and highly variable penetrance even within individual families carrying the same genetic variant.

Emergency department extracorporeal membrane oxygenation as a rescue therapy for ventricular tachycardia electrical storm: a case report

Arrhythmogenic right ventricular cardiomyopathy is a cause of sudden cardiac death in often otherwise healthy young adults. Cardiac arrest following an unstable tachydysrhythmia may be the primary presenting symptom. Venous arterial extracorporeal life support via extracorporeal membrane oxygenation (VA ECMO) has been used as a rescue strategy in emergency departments (EDs) for patients with cardiac arrest unresponsive to conventional cardiopulmonary resuscitation. We present a case of a previously healthy 18-year-old male who presented to our emergency department with ECG features of arrhythmogenic right ventricular cardiomyopathy and subsequent pulseless polymorphic ventricular tachycardia refractory cardiac arrest, treated with ED-initiated VA ECMO.

Clinical Presentation, Cardiac Magnetic Resonance Findings, and Prognosis of Patients with Arrhythmogenic Right Ventricular Cardiomyopathy - An Experience from Pakistan

Objectives:

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart-muscle disease, characterized by fibro-fatty replacement and ventricular arrhythmias, that primarily affects the right ventricle (RV). We aimed to look at the clinical presentation, cardiac magnetic resonance (CMR) imaging findings and prognosis of patients with ARVC in Pakistan.

Material and Methods:

It is a retrospective observational study, 17 consecutive patients with CMR and other findings consistent with ARVC, were enrolled from 2010 to 2019 at a single center.

Results:

Out of 17 patients, 12 (70.6%) were male with a mean age of 33.5 ± 17.5 years. Family history of sudden cardiac death was present in 3 (17.7%) patients while one (5.9%) patient had family history of ARVC. Syncope was the first presenting symptom in eight (47.1%) patients. On 12 leads ECG, T wave inversion in precordial leads was found in 6 (35.4%) patients, and epsilon wave was present in only 3 (17.7%) patients. On echocardiogram, 13 (76.5%) patients had dilated RV with reduced systolic function. On CMR, majority of patients (n = 14, 82.4%) were found to have RV dilatation with regional dyskinesia and fatty infiltration, 9 (52.9%) of them had left ventricular involvement also. Follow-up was available for 14 patients (82.4%) with a mean follow-up period of 35.5 ± 19.7 months. Three (21.4%) of them died and 10 (71.4%) got admissions for heart failure during follow-up period.

Conclusion:

Arrhythmia related events are the main presenting symptoms of ARVC in this region, and left ventricular involvement in ARVC is not rare in this population. The mortality is relatively high, probably due to advanced disease at the time of presentation and less medical facilities available.

Arrhythmic risk stratification by cardiac magnetic resonance tissue characterization: disclosing the arrhythmic substrate within the heart muscle

Sudden cardiac death (SCD) is a pivotal health problem worldwide. The identification of subjects at increased risk of SCD is crucial for the accurate selection of candidates for implantable cardioverter defibrillator (ICD) therapy. Current strategies for arrhythmic stratification largely rely on left ventricular (LV) ejection fraction (EF), mostly measured by echocardiography, and New York Heart Association functional status for heart failure with reduced EF. For specific diseases, such as hypertrophic and arrhythmogenic cardiomyopathy, some risk scores have been proposed; however, these scores take into account some parameters that are a partial reflection of the global arrhythmic risk and show a suboptimal accuracy. Thanks to a more comprehensive evaluation, cardiac magnetic resonance (CMR) provides insights into the heart muscle (the so-called tissue characterization) identifying cardiac fibrosis as an arrhythmic substrate. Combining sequences before and after administration of contrast media and mapping techniques, CMR is able to characterize the myocardial tissue composition, shedding light on both intracellular and extracellular alterations. Over time, late gadolinium enhancement (LGE) emerged as solid prognostic marker, strongly associated with major arrhythmic events regardless of LVEF, adding incremental value over current strategy in ischemic heart disease and non-ischemic cardiomyopathies. The evidence on a potential prognostic role of mapping imaging is promising. However, mapping techniques require further investigation and standardization. Disclosing the arrhythmic substrate within the myocardium, CMR should be considered as part of a multiparametric approach to personalized arrhythmic stratification.

Safety and Utility of Cardiopulmonary Exercise Testing in Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

Background

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is characterized by high arrhythmic burden and progressive heart failure, which can prompt referral for heart transplantation. Cardiopulmonary exercise testing (CPET) has an established role in risk stratification for advanced heart failure therapies, but has not been described in ARVC/D. This study sought to determine the safety and prognostic utility of CPET in patients with ARVC/D.

Methods and Results

Using the Johns Hopkins ARVC/D Registry, we examined patients with ARVC/D undergoing CPET. Baseline characteristics and transplant‐free survival were compared on the basis of peak oxygen consumption (pVO2) (≤14 or >14 mL/kg per minute) and ventilatory efficiency (Ve/VCO₂ slope ≤34 or >34). Thirty‐eight patients underwent 50 CPETs. There were no sustained arrhythmic events. Twenty‐nine patients achieved a maximal test. Patients with pVO2 ≤14 mL/kg per minute were more often men (P=0.042) compared with patients with pVO2 >14 mL/kg per minute. Patients with Ve/VCO₂ slope >34 tended to have more moderate/severe right ventricular dilation (7/9 [78%] versus 10/26 [38%]; P=0.060) and clinical heart failure (8/9 [89%] versus 13/26 [50%]; P=0.056) compared with patients with Ve/VCO₂ slope ≤34. Patients who underwent heart transplantation were more likely to have clinical heart failure (10/10 [100%] versus 13/28 [46%]; P=0.003). Patients with Ve/VCO₂ slope >34 had worse transplant‐free survival compared with patients with Ve/VCO₂ slope ≤34 (n=35; hazard ratio, 6.57 [95% CI, 1.28–33.72]; log‐rank P=0.010), whereas transplant‐free survival was similar on the basis of pVO2 groups (n=29; hazard ratio, 3.38 [95% CI, 0.75–15.19]; log‐rank P=0.092).

Conclusions

CPET is safe to perform in patients with ARVC/D. Ve/VCO₂ slope may be used for risk stratification and guide referral for heart transplantation in ARVC/D.