Predictors of appropriate implantable defibrillator therapies in patients with arrhythmogenic right ventricular dysplasia

BACKGROUND Arrhythmogenic right ventricular dysplasia (ARVD) is an inherited cardiomyopathy characterized by ventricular arrhythmias and sudden cardiac death. The risk factors for sudden death and indications for implantable cardioverter-defibrillator (ICD) placement in patients with ARVD are not well defined. OBJECTIVES The purpose of this study was to determine which clinical and electrophysiologic variables best predict appropriate ICD therapies in patients with ARVD. Particular attention focused on whether the ICD was implanted for primary or second prevention. METHODS We enrolled 67 patients (mean age 36 +/- 14 years) with definite or probable ARVD who had undergone ICD placement. Appropriate ICD therapies were recorded, and Kaplan-Meier analysis was used to compare the event-free survival time between patients based upon the indication for ICD placement (primary vs secondary prevention), results of electrophysiologic testing. and whether the patient had probable or definite ARVD. RESULTS Over a mean follow-up of 4.4 +/- 2.9 years, 40 (73 7) of 55 patients who met task force criteria for ARVD and 4 (33%) of 12 patients with probable ARVD had appropriate ICD therapies for ventricular tachycardia/ventricular fibrillation (VT/VF; P =.027). Mean time to ICD therapy was 1.1 +/- 1.4 years. Eleven of 28 patients who received an ICD for primary prevention (39%) and 33 of 35 patients who received an ICD for secondary prevention (85%) experienced appropriate ICD therapies (P =.001). Electrophysiologic testing did not predict appropriate ICD interventions in patients who received an ICD for primary prevention. Fourteen patients (21%) received ICD therapy for life-threatening (VT/VF > 240 bpm) arrhythmias. There was no difference in the incidence of life-threatening arrhythmias in the primary and secondary prevention groups (P =.29). CONCLUSION Patients who meet task force criteria for ARVD are at high risk for sudden cardiac death and should undergo ICD placement for primary and secondary prevention, regardless of electrophysiologic testing results. Further research is needed to confirm that a low-risk Subset of patients who may not require ICD placement can be identified.