Incidence of and predictors for appropriate implantable cardioverter-defibrillator therapy in patients with a secondary preventive implantable cardioverter-defibrillator indication

Abstract

Aims: Incidence of implantable cardioverter-defibrillator (ICD) therapy in secondary prevention has been assessed in randomized trials and registries. However, results are considerably limited by short follow-up and hazy definition of treated arrhythmias. This study aimed to determine appropriate ICD therapy and to define predictors based on registry patients followed for up to 20 years.

Methods and results: All patients with a secondary prevention indication and ischaemic or dilated cardiomyopathy were identified. Arrhythmic endpoints were appropriate ICD therapies for any ventricular tachycardia (VT) >175 b.p.m. and appropriate ICD therapies in the ventricular fibrillation (VF) zone of >220 b.p.m. (potentially life-threatening). Predictors were determined by analysing 19 baseline characteristics. We included 357 patients, age 65 ± 11 years, predominantly male (89%) with ischaemic cardiomyopathy (83%). During follow-up of 82 ± 53 months, 156 (44%) patients died and 208 received any form of ICD therapies (59%), 71 of them (34%) in the VF zone. Forty-four patients (28%) died without experiencing any form of appropriate ICD therapy. Cumulative incidence of any form of ICD therapy at 10 years was 65%. Predictors for any form of ICD therapy were implantation for VT and age [VT: hazard ratio (HR) 1.45, 95% confidence interval (95% CI) 1.05-2.01, P = 0.03; age (per year): HR 1.02, 95% CI 1.01-1.04, P = 0.001]. For therapy in the VF zone, univariate analysis determined male gender (29 vs. 5%, P = 0.01) as predictor.

Conclusion: The rate of appropriate ICD therapies in secondary prevention is high. No useful predictors for them, especially not for life-threatening arrhythmias could be identified.

Keywords: Cumulative incidence; Implantable cardioverter-defibrillator; Predictor; Secondary prevention.