Background-The

Background-Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a condition associated with the risk of sudden death (SD). Methods and Results-We conducted a multicenter study of the impact of the implantable cardioverter-defibrillator (ICD) for prevention of SD in 132 patients (93 males and 39 females, age 40Ϯ15 years) with ARVC/D. Implant indications were a history of cardiac arrest in 13 patients (10%), sustained ventricular tachycardia in 82 (62%), syncope in 21 (16%), and other in 16 (12%). During a mean follow-up of 39Ϯ25 months, 64 patients (48%) had appropriate ICD interventions, 21 (16%) had inappropriate interventions, and 19 (14%) had ICD-related complications. Fifty-three (83%) of the 64 patients with appropriate interventions received antiarrhythmic drug therapy at the time of first ICD discharge. Programmed ventricular stimulation was of limited value in identifying patients at risk of tachyarrhythmias during the follow-up (positive predictive value 49%, negative predictive value 54%). Four patients (3%) died, and 32 (24%) experienced ventricular fibrillation/flutter that in all likelihood would have been fatal in the absence of the device. At 36 months, the actual patient survival rate was 96% compared with the ventricular fibrillation/flutter-free survival rate of 72% (PϽ0.001). Patients who received implants because of ventricular tachycardia without hemodynamic compromise had a significantly lower incidence of ventricular fibrillation/flutter (log rankϭ0.01). History of cardiac arrest or ventricular tachycardia with hemodynamic compromise, younger age, and left ventricular involvement were independent predictors of ventricular fibrillation/flutter. Conclusions-In

Background— Three-dimensional electroanatomic voltage mapping offers the potential to identify low-voltage areas that correspond to regions of right ventricular (RV) myocardial loss and fibrofatty replacement in patients with arrhythmogenic RV cardiomyopathy/dysplasia (ARVC/D). Methods and Results— Thirty-one consecutive patients (22 men and 9 women; mean age, 30.8±7 years) who fulfilled the criteria of the Task Force of the European Society of Cardiology and International Society and Federation of Cardiology (ESC/ISFC) for ARVC/D diagnosis after noninvasive clinical evaluation underwent further invasive study including RV electroanatomic voltage mapping and endomyocardial biopsy (EMB) to validate the diagnosis. Multiple RV endocardial, bipolar electrograms (175±23) were sampled during sinus rhythm. Twenty patients (group A; 65%) had an abnormal RV electroanatomic voltage mapping showing ≥1 area (mean 2.25±0.7) with low-voltage values (bipolar electrogram amplitude <0.5 mV), surrounded by a border zone (0.5 to 1.5 mV) that transitioned into normal myocardium (>1.5 mV). Low-voltage electrograms appeared fractionated with significantly prolonged duration and delayed activation. In 11 patients (group B; 35%), electroanatomic voltage mapping was normal, with preserved electrogram voltage (4.4±0.7 mV) and duration (37.2±0.9 ms) throughout the RV. Low-voltage areas in patients from group A corresponded to echocardiographic/angiographic RV wall motion abnormalities and were significantly associated with myocyte loss and fibrofatty replacement at EMB ( P <0.0001) and familial ARVC/D ( P <0.0001). Patients from group B had sporadic disease and histopathological evidence of inflammatory cardiomyopathy ( P <0.0001). During the time interval from onset of symptoms to the invasive study, 11 patients (55%) with electroanatomic low-voltage regions received an implantable cardioverter/defibrillator because of life-threatening ventricular arrhythmias, whereas all but 1 patient with a normal voltage map remained stable on antiarrhythmic drug therapy ( P =0.02). Conclusions— Three-dimensional electroanatomic voltage mapping enhanced accuracy for diagnosing ARVC/D (1) by demonstrating low-voltage areas that were associated with fibrofatty myocardial replacement and (2) by identifying a subset of patients who fulfilled ESC/ISFC Task Force diagnostic criteria but showed a preserved electrogram voltage, an inflammatory cardiomyopathy mimicking ARVC/D, and a better arrhythmic outcome.