Diagnostic Value of Isoproterenol Testing in Arrhythmogenic Right Ventricular Cardiomyopathy

Background-Although the Task Force Criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC) have recently been updated, the diagnosis remains challenging in the early stages. The aim of this study was to evaluate the diagnostic value of beta-adrenergic stimulation in ARVC. Methods and Results-We evaluated 412 consecutive patients (213 men, age 41.5+/-16 years) referred for premature ventricular contractions evaluation or suspected ARVC. Isoproterenol testing was performed with continuous infusion of isoproterenol (45 mu g/min) for 3 minutes. It was considered positive if there were either (1) polymorphic premature ventricular contractions with >= 1 couplet or (2) sustained or nonsustained ventricular tachycardia with left bundle branch block excluding right ventricular outflow tract ventricular tachycardia. ARVC was diagnosed in 35 patients at initial evaluation (23 men, aged 42+/-15 years). Isoproterenol testing was positive in 32 of 35 (91.4%) patients with ARVC and in 42 of 377 (11.1%) patients without ARVC (P<0.0001). Sensitivity, specificity, positive, and negative predictive values of isoproterenol testing to diagnose ARVC were 91.4%, 88.9%, 43.2%, and 99.1%, respectively. During a mean follow-up period of 5.6+/-4.4 years, 6 additional patients met diagnostic criteria for ARVC. Importantly, initial isoproterenol testing was positive in 6 of 6 (100%) of these patients. Survival free from ARVC diagnosis was significantly lower in the positive isoproterenol group than in the negative isoproterenol group (P<0.0001, exact log-rank test). Conclusions-Ventricular arrhythmogenicity during isoproterenol testing is highly sensitive (sensitivity, 91.4%) for the diagnosis of ARVC, particularly in its early stages.