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.

Introduction The traditional description of the Triangle of Dysplasia in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C) predates genetic testing and excludes biventricular phenotypes. Methods and Results We analyzed Cardiac Magnetic Resonance (CMR) studies of 74 mutation-positive ARVD/C patients for regional abnormalities on a 5-segment RV and 17-segment LV model. The location of electroanatomic endo- and epicardial scar and site of successful VT ablation was recorded in 11 ARVD/C subjects. Among 54/74 (73%) subjects with abnormal CMR, the RV was abnormal in almost all (96%), and 52% had biventricular involvement. Isolated LV abnormalities were uncommon (4%). Dyskinetic basal inferior wall (94%) was the most prevalent RV abnormality, followed by basal anterior wall (87%) dyskinesis. Subepicardial fat infiltration in the posterolateral LV (80%) was the most frequent LV abnormality. Similar to CMR data, voltage maps revealed scar (<0.5 mV) in the RV basal inferior wall (100%), followed by the RV basal anterior wall (64%) and LV posterolateral wall (45%). All 16 RV VTs originated from the basal inferior wall (50%) or basal anterior wall (50%). Of 3 LV VTs, 2 localized to the posterolateral wall. In both modalities, RV apical involvement never occurred in isolation. Conclusion Mutation-positive ARVD/C exhibits a previously unrecognized characteristic pattern of disease involving the basal inferior and anterior RV, and the posterolateral LV. The RV apex is only involved in advanced ARVD/C, typically as a part of global RV involvement. These results displace the RV apex from the Triangle of Dysplasia, and provide insights into the pathophysiology of ARVD/C.

A rrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited cardiomyopathy characterized by progressive fibrofatty replacement of the right ventricular myocardium. Structural abnormalities can be diffuse 1 and provide a substrate for reentrant ventricular tachycardia (VT). Studies have shown a significantly high incidence of ventricular arrhythmias 2-4 among patients with ARVD/C. Although the risk of sudden death is mitigated by implantable cardioverterdefibrillator (ICD) implantation, recurrent ICD firings due to rapid ventricular arrhythmias are common 5 and often a cause of significant morbidity in these patients. Radiofrequency catheter ablation (RFA) is increasingly used in the management of VT in ARVD/C. Early studies evaluating the efficacy of catheter ablation of VT among patients with ARVD/C reported varied outcomes using an endocardial-based ablation strategy and have mostly reported outcomes performed in referral centers specialized in VT ablation. [6][7][8][9] However, there have been recent advances in the technology related to catheter ablation and a better understanding of the VT substrate in ARVD/C. The reasons for failure after catheter ablation of VT are attributed to predominant epicardial distribution of the disease, existence of multiple reentrant pathways, and possibly a progressive disease process. In keeping with these findings, several recent studies have reported significantly lower VT recurrence among patients with ARVD/C who underwent an epicardial substratebased ablation strategy. 10,11Clinical Perspective on p 505The purpose of the present study was to report multicenter outcomes of catheter ablation of VT in a large series of patients with ARVD/C who were enrolled in the Johns Hopkins ARVD Registry (www.arvd.com). There were 3 main goals: (1) to determine whether catheter ablation outcomes for ARVD/C have improved with use of electroanatomic Received October 28, 2011; accepted March 19, 2012. 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 followup 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