Brittney Murray

Exercise increases age-related penetrance and arrhythmic risk in arrhythmogenic right ventricular dysplasia/cardiomyopathy-associated desmosomal mutation carriers.

OBJECTIVES This study sought to determine how exercise influences penetrance of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) among patients with desmosomal mutations. BACKGROUND Although animal models and anecdotal evidence suggest that exercise is a risk factor for ARVD/C, there have been no systematic human studies. METHODS Eighty-seven carriers (46 male; mean age, 44 ± 18 years) were interviewed about regular physical activity from 10 years of age. The relationship of exercise with sustained ventricular arrhythmia (ventricular tachycardia/ventricular fibrillation [VT/VF]), stage C heart failure (HF), and meeting diagnostic criteria for ARVD/C (2010 Revised Task Force Criteria [TFC]) was studied. RESULTS Symptoms developed in endurance athletes (N = 56) at a younger age (30.1 ± 13.0 years vs. 40.6 ± 21.1 years, p = 0.05); they were more likely to meet TFC at last follow-up (82% vs. 35%, p < 0.001) and have a lower lifetime survival free of VT/VF (p = 0.013) and HF (p = 0.004). Compared with those who did the least exercise per year (lowest quartile) before presentation, those in the second (odds ratio [OR]: 6.64, p = 0.013), third (OR: 16.7, p = 0.001), and top (OR: 25.3, p < 0.0001) quartiles were increasingly likely to meet TFC. Among 61 individuals who did not present with VT/VF, the 13 subjects experiencing a first VT/VF event over a mean follow-up of 8.4 ± 6.7 years were all endurance athletes (p = 0.002). Survival from a first VT/VF event was lowest among those who exercised most (top quartile) both before (p = 0.036) and after (p = 0.005) clinical presentation. Among individuals in the top quartile, a reduction in exercise decreased VT/VF risk (p = 0.04). CONCLUSIONS Endurance exercise and frequent exercise increase the risk of VT/VF, HF, and ARVD/C in desmosomal mutation carriers. These findings support exercise restriction for these patients.

Incidence and Predictors of Implantable Cardioverter-Defibrillator Therapy in Patients With Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy Undergoing Implantable Cardioverter-Defibrillator Implantation for Primary Prevention

OBJECTIVES The purpose of this study was to define the incidence and predictors of implantable cardioverter-defibrillator (ICD) therapy in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) after placement of an ICD for primary prevention. BACKGROUND Patients with a diagnosis of ARVD/C often receive an ICD for prevention of sudden cardiac death. METHODS Patients (n = 84) from the Johns Hopkins registry with definite or probable ARVD/C who underwent ICD implantation for primary prevention were studied. Detailed phenotypic, genotype, and ICD event information was obtained and appropriate ICD therapies were adjudicated based on intracardiac electrograms. RESULTS Over a mean follow-up of 4.7 ± 3.4 years, appropriate ICD therapy was seen in 40 patients (48%), of whom 16 (19%) received interventions for potentially fatal ventricular fibrillation/flutter episodes. Proband status (p < 0.001), inducibility at electrophysiologic study (p = 0.005), presence of nonsustained ventricular tachycardia (p < 0 .001), and Holter premature ventricular complex count >1,000/24 h (p = 0.024) were identified as significant predictors of appropriate ICD therapy. The 5-year survival free of appropriate ICD therapy for patients with 1, 2, 3, and 4 risk factors was 100%, 83%, 21%, and 15%, respectively. Inducibility at electrophysiologic study (hazard ratio: 4.5, 95% confidence interval: 1.4 to 15, p = 0.013) and nonsustained ventricular tachycardia (hazard ratio: 10.5, 95% confidence interval: 2.4 to 46.2, p = 0.002) remained as significant predictors on multivariable analysis. CONCLUSIONS Nearly one-half of the ARVD/C patients with primary prevention ICD implantation experience appropriate ICD interventions. Inducibility at electrophysiologic study and nonsustained ventricular tachycardia are independent strong predictors of appropriate ICD therapy. An increase in ventricular ectopy burden was associated with progressively lower event-free (appropriate ICD interventions) survival. Incremental risk of ventricular arrhythmias and ICD therapy was observed with the presence of multiple risk factors.

Clinical Presentation, Long-Term Follow-Up, and Outcomes of 1001 Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy Patients and Family Members

Background—Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a progressive cardiomyopathy. We aimed to define long-term outcome in a transatlantic cohort of 1001 individuals. Methods and Results—Clinical and genetic characteristics and follow-up data of ARVD/C index-patients (n=439, fulfilling of 2010 criteria in all) and family members (n=562) were assessed. Mutations were identified in 276 index-patients (63%). Index-patients presented predominantly with sustained ventricular arrhythmias (268; 61%). During a median follow-up of 7 years, 301 of the 416 index-patients presenting alive (72%) experienced sustained ventricular arrhythmias. Sudden cardiac death during follow-up occurred more frequently among index-patients without an implantable cardioverter-defibrillator (10/63, 16% versus 2/335, 0.6%). Overall, cardiac mortality and the need for cardiac transplantation were low (6% and 4%, respectively). Clinical characteristics and outcomes were similar in index-patients with and without mutations, as well as in those with familial and nonfamilial ARVD/C. ARVD/C was diagnosed in 207 family members (37%). Symptoms at first evaluation correlated with disease expression. Family members with mutations were more likely to meet Task Force Criteria for ARVD/C (40% versus 18%), experience sustained ventricular arrhythmias (11% versus 1%), and die from a cardiac cause (2% versus 0%) than family members without mutations. Conclusions—Long-term outcome was favorable in diagnosed and treated ARVD/C index-patients and family members. Outcome in index-patients was modulated by implantable cardioverter-defibrillator implantation, but not by mutation status and familial background of disease. One third of family members developed ARVD/C. Outcome in family members was determined by symptoms at first evaluation and mutations.

Outcomes of catheter ablation of ventricular tachycardia in arrhythmogenic right ventricular dysplasia/cardiomyopathy.

Background—Prior studies evaluating the efficacy of catheter ablation of ventricular tachycardia (VT) among patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) have reported varied outcomes. More recently, studies have suggested that an epicardial ablation is necessary for improved outcomes after catheter ablation of VT. The overall objective of the present study was to assess the efficacy of radiofrequency catheter ablation (RFA) of VT in ARVD/C, with particular focus on newer ablation strategies, including epicardial catheter ablation. Methods and Results—The study population included 87 patients with ARVD/C who underwent a total of 175 RFA procedures between 1992 and 2011 at 80 different electrophysiology centers. Recurrence of VT following RFA and effect of RFA on the burden of VT were assessed. The mean age of the cohort was 38 ± 13 years. Over a mean follow-up of 88.3 ± 66 months, the overall freedom from VT of the 175 procedures was 47%, 21%, and 15%, at 1, 5, and 10 years, respectively. The cumulative freedom from VT following epicardial RFA was 64% and 45% at 1 and 5 years, respectively, which was significantly longer than endocardial RFA (P=0.021). Survival free of VT among procedures with 3D electroanatomic mapping was significantly longer compared to those without (P=0.016). Burden of VT was reduced irrespective of the ablation strategy (P<0.001). Conclusions—Although VT recurrences are common, RFA results in a significant reduction in the burden of VT in patients with ARVD/C. Further, although the use of 3D electroanatomic mapping systems and epicardial ablation strategies are associated with longer survival free of VT, recurrence rates remain considerable.

Impact of genotype on clinical course in arrhythmogenic right ventricular dysplasia/cardiomyopathy-associated mutation carriers

AIMS We sought to determine the influence of genotype on clinical course and arrhythmic outcome among arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)-associated mutation carriers. METHODS AND RESULTS Pathogenic mutations in desmosomal and non-desmosomal genes were identified in 577 patients (241 families) from USA and Dutch ARVD/C cohorts. Patients with sudden cardiac death (SCD)/ventricular fibrillation (VF) at presentation (n = 36) were younger (median 23 vs. 36 years; P < 0.001) than those presenting with sustained monomorphic ventricular tachycardia (VT). Among 541 subjects presenting alive, over a mean follow-up of 6 ± 7 years, 12 (2%) patients died, 162 (30%) had sustained VT/VF, 78 (14%) manifested left ventricular dysfunction (EF < 55%), 28 (5%) experienced heart failure (HF), and 10 (2%) required cardiac transplantation. Patients (n = 22; 4%) with >1 mutation had significantly earlier occurrence of sustained VT/VF (mean age 28 ± 12 years), lower VT-/VF-free survival (P = 0.037), more frequent left ventricular dysfunction (29%), HF (19%) and cardiac transplantation (9%) when compared with those with only one mutation. Desmoplakin mutation carriers experienced more than four-fold occurrence of left ventricular dysfunction (40%) and HF (13%) than PKP2 carriers. Missense mutation carriers had similar death-/transplant-free survival and VT/VF penetrance (P = 0.137) when compared with those with truncating or splice site mutations. Men are more likely to be probands (P < 0.001), symptomatic (P < 0.001) and have earlier and more severe arrhythmic expression. CONCLUSIONS Presentation with SCD/VF occurs at a significantly younger age when compared with sustained monomorphic VT. The genotype of ARVD/C mutation carriers impacts clinical course and disease expression. Male sex negatively modifies phenotypic expression.

Outcomes of Catheter Ablation of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C)

Background—Prior studies evaluating the efficacy of catheter ablation of ventricular tachycardia (VT) among patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) have reported varied outcomes. More recently, studies have suggested that an epicardial ablation is necessary for improved outcomes after catheter ablation of VT. The overall objective of the present study was to assess the efficacy of radiofrequency catheter ablation (RFA) of VT in ARVD/C, with particular focus on newer ablation strategies, including epicardial catheter ablation. Methods and Results—The study population included 87 patients with ARVD/C who underwent a total of 175 RFA procedures between 1992 and 2011 at 80 different electrophysiology centers. Recurrence of VT following RFA and effect of RFA on the burden of VT were assessed. The mean age of the cohort was 38 ± 13 years. Over a mean follow-up of 88.3 ± 66 months, the overall freedom from VT of the 175 procedures was 47%, 21%, and 15%, at 1, 5, and 10 years, respectively. The cumulative freedom from VT following epicardial RFA was 64% and 45% at 1 and 5 years, respectively, which was significantly longer than endocardial RFA (P=0.021). Survival free of VT among procedures with 3D electroanatomic mapping was significantly longer compared to those without (P=0.016). Burden of VT was reduced irrespective of the ablation strategy (P<0.001). Conclusions—Although VT recurrences are common, RFA results in a significant reduction in the burden of VT in patients with ARVD/C. Further, although the use of 3D electroanatomic mapping systems and epicardial ablation strategies are associated with longer survival free of VT, recurrence rates remain considerable.

Incremental Value of Cardiac Magnetic Resonance Imaging in Arrhythmic Risk Stratification of Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy–Associated Desmosomal Mutation Carriers

OBJECTIVES The aim of this study was to identify the incremental value and optimal role of cardiac magnetic resonance (CMR) imaging in arrhythmic risk stratification of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)-associated desmosomal mutation carriers without histories of sustained ventricular arrhythmia. BACKGROUND Risk stratification of ARVD/C mutation carriers is challenging. METHODS Sixty-nine patients (mean age 27.0 ± 15.3 years, 42% men) harboring ARVD/C-associated pathogenic mutations (83% plakophilin 2) without prior sustained ventricular arrhythmias were included. Electrocardiographic and 24-h Holter monitoring findings closest to presentation were analyzed for electrical abnormalities per revised task force criteria. CMR studies were done to identify abnormal cardiac structure and function according to the revised task force criteria. RESULTS Overall, 42 patients (61%) presented with electrical abnormalities on the basis of electrocardiography and Holter monitoring, of whom 20 (48%) had abnormal results on CMR. Only 1 of 27 patients (4%) without electrical abnormalities at initial evaluation had abnormal CMR results. Over a mean follow-up period of 5.8 ± 4.4 years, 11 patients (16%) experienced sustained ventricular arrhythmias, exclusively in patients with both electrical abnormalities (electrocardiography and/or Holter monitoring) and abnormal CMR results. CONCLUSIONS These results suggest that electrical abnormalities on electrocardiography and Holter monitoring precede detectable structural abnormalities in ARVD/C mutation carriers. Therefore, evaluation of cardiac structure and function using CMR is probably not necessary in the absence of baseline electrical abnormalities. Among ARVD/C mutation carriers, the presence of both electrical and CMR abnormalities identifies patients at high risk for events and thus patients who might benefit from prophylactic implantable cardioverter-defibrillator placement.

Exercise has a Disproportionate Role in the Pathogenesis of Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy in Patients Without Desmosomal Mutations

Background Exercise is associated with age‐related penetrance and arrhythmic risk in carriers of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)‐associated desmosomal mutations; however, its role in patients without desmosomal mutations (gene‐elusive) is uncertain. This study investigates whether exercise is (1) associated with onset of gene‐elusive ARVD/C and (2) has a differential impact in desmosomal and gene‐elusive patients. Methods and Results Eighty‐two ARVD/C patients (39 desmosomal, all probands) were interviewed about regular physical activity from age 10. Participation in endurance athletics, duration (hours/year), and intensity (MET‐Hours/year) of exercise prior to clinical presentation were compared between patients with desmosomal and gene‐elusive ARVD/C. All gene‐elusive patients were endurance athletes. Gene‐elusive patients were more likely to be endurance athletes (P<0.001) and had done significantly more intense (MET‐Hrs/year) exercise prior to presentation (P<0.001), particularly among cases presenting < age 25 (P=0.027). Family history was less prevalent among gene‐elusive patients (9% versus 40% desmosomal, P<0.001), suggesting a greater environmental influence. Gene‐elusive patients without family history did considerably more intense exercise than other ARVD/C patients (P=0.004). Gene‐elusive patients who had done the most intense (top quartile MET‐Hrs/year) exercise prior to presentation had a younger age of presentation (P=0.025), greater likelihood of meeting ARVD/C structural Task Force Criteria (100% versus 43%, P=0.02), and shorter survival free from a ventricular arrhythmia in follow‐up (P=0.002). Conclusions Gene‐elusive, non‐familial ARVD/C is associated with very high intensity exercise suggesting exercise has a disproportionate role in the pathogenesis of these cases. As exercise negatively modifies cardiac structure and promotes arrhythmias, exercise restriction is warranted.

Risk Stratification in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy Associated Desmosomal Mutation Carriers

Background—We investigated the role of phenotypic characteristics in stratifying the risk of sustained ventricular arrhythmias in patients harboring arrhythmogenic right ventricular dysplasia/cardiomyopathy–associated mutations. Methods and Results—Clinical, electrocardiographic, and arrhythmic outcome (composite measure of first occurrence of sustained ventricular tachycardia/resuscitated sudden cardiac death/sudden cardiac death/appropriate implantable cardioverter-defibrillator therapy) data were obtained for 215 patients (104 families; 85% PKP-2). During a mean follow-up of 7 years, 86 (40%) patients experienced the arrhythmic outcome. Event-free survival was significantly lower among probands (P<0.001) and symptomatic (P<0.001) patients. Integration of ECG repolarization and depolarization abnormalities allowed for differential risk categorization. Event-free survival at 5 years for the low-risk ECG group (0–1 T inversions or minor depolarization changes) was 97% versus 81% for the intermediate-risk ECG group (2 T inversions+minor depolarization changes) versus 33% for the high-risk ECG group (≥3 T inversions±major or minor depolarization changes; P<0.001). Incremental arrhythmic risk was seen in patients with increasing premature ventricular complex count on a Holter (P<0.001). Proband status (hazard ratio, 7.7; 95% confidence interval, 2.8–22.5; P<0.001), ≥3 T-wave inversions (hazard ratio, 4.2; 95% confidence interval, 1.2–14.5; P=0.035), and male sex (hazard ratio, 1.8; 95% confidence interval, 1.2–2.8; P=0.004) were independent predictors of the first arrhythmic event on multivariable analysis. Conclusions—Pedigree evaluation, an ECG, and a Holter examination provide for comprehensive arrhythmic risk stratification in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy–associated mutations. We propose an approach to risk stratification based on these variables.

Mutation-Positive Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy: The Triangle of Dysplasia Displaced

The traditional description of the Triangle of Dysplasia in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C) predates genetic testing and excludes biventricular phenotypes.