Incidence and clinical significance of short-term recurrent ventricular tachyarrhythmias in patients with implantable cardioverter-defibrillator

Aims of the present study were (1) to investigate the clinical significance of short-term recurrent tachyarrhythmias (STRTs) in ICD recipient, (2) to identify basic characteristics of the subgroup of patients with STRTs and (3) to compare the frequency and circadian pattern of single arrhythmic events and STRTs. We reviewed data from 119 consecutive patients with late generation ICD. All registered spontaneous ventricular tachyarrhythmias were divided into STRTs (defined as two or more consecutive episodes separated by ≤1 h of sinus rhythm) and single events. During a mean follow up of 36±18 months (range 2–67 months) 1849 ventricular arrhythmic events were detected in 57 out of 119 ICD recipients (48%). 202 STRTs consisting of 1128 single detection (6±7/STRT, range 2–52) occurred in 34/57 patients (60%; 6±6 per patient, range 1–21). Recurrent ventricular tachycardias before device implantation and a high number of single arrhythmic events during follow-up distinguished patients with STRTs. Cardiac mortality was significantly higher in patients with STRTs (26 vs. 4%, P<0.05). The majority of both single episodes and STRTs were registered between 8 a.m. and noon and in the evening. This study reveals a high incidence of STRTs in ICD recipients with spontaneous tachyarrhythmias during follow-up and identifies STRTs as prognostic significant events. Comparable circadian variations suggest that similar triggering factors may be involved in the genesis of STRTs and single tachyarrhythmias.