Introduction: We evaluated the potential ability of the electrophysiological (EP) inducibility of ventricular arrhythmias to predict the likelihood of appropriate ICD intervention over the long-term in ischemic and nonischemic patients with current primary prevention indications for ICD implantation.
Methods: Between 2006 and 2008, 206 consecutive heart failure patients who were candidates for ICD implantation for the primary prevention of sudden cardiac death according to standard indications underwent EP testing, usually on ICD implantation.
Results: On EP testing, 15 (7%) patients had inducible monomorphic ventricular tachycardia (VT) and 14 (7%) ventricular fibrillation (VF). Over 24 months, 64 (31%) patients received appropriate ICD therapies: 51 (25%) for VT and 16 (8%) for VF. The time to the first appropriate ICD therapy trended to be shorter in the group of patients who were inducible on EP testing (p=0.072). Among patients receiving appropriate therapies, the median number of arrhythmic episodes was 2, and the proportion of patients with 2 treated arrhythmic episodes was higher in the group of inducible patients (34% versus 14%, p=0.005). On multivariate analysis, inducibility proved to be an independent predictor of frequent (2) arrhythmic episodes, as did a history of coronary artery bypass grafting. Moreover, patients with 2 treated arrhythmic episodes showed higher mortality (log-rank test, p=0.042).
Conclusion: Patients with inducibility of VT or VF are more likely to experience frequent appropriate ICD therapies during follow up.