Characteristics of ventricular tachyarrhythmias occurring in ischemic versus nonischemic patients implanted with a biventricular cardioverter-defibrillator for primary or secondary prevention of sudden death

Objectives: The InSync ICD Registry evaluated patients indicated for cardiac resynchronization therapy with defibrillation. Background: Cardiac resynchronization therapy with defibrillation systems are prescribed for both primary and secondary prevention of sudden cardiac death in patients with heart failure with both ischemic and nonischemic etiology. The characterization of ventricular tachyarrhythmias detected by the ICD is not well known in these subpopulations. Methods: We enrolled 421 patients with symptomatic heart failure despite optimized medical treatment, ventricular dyssynchrony, and primary or secondary ICD indications. An electrophysiologist reviewed all spontaneous episodes. Patients were grouped by etiology and ICD indications. Results: The 421 patients included 292 ischemic (159 primary prevention) and 129 nonischemic (68 primary prevention) patients. In 19 ± 11 months of follow-up, 110 patients (63 ischemic, 30 primary prevention and 47 nonischemic, 21 primary prevention) presented ventricular tachyarrhythmias, occurring in a ventricular tachycardia (VT) or a ventricular fibrillation zone (1382 and 456 events, respectively). The incidence of overall ventricular tachyarrhythmias in nonischemic patients in secondary prevention (35.7% at 1 year) was higher than in ischemic patients implanted for either indication (16.5% and 22.9% at 1 year, respectively). The incidence of self-terminating ventricular tachyarrhythmias was greater in patients with nonischemic heart disease, regardless of indication. Patients with ischemic heart disease in primary prevention had a lower occurrence of VTs, whereas nonischemic patients in primary prevention had faster VTs. Conclusions: Both rate of occurrence and characteristics of detected ventricular tachyarrhythmias vary according to underlying etiology and indication. Therefore, different device programming according to patient's profile is advisable to improve ventricular tachyarrhythmias management.