Incidence of ventricular arrhythmias and 1-year predictors of mortality in patients treated with implantable cardioverter-defibrillator undergoing generator replacement

BACKGROUND: When implantable cardioverter defibrillator (ICD) battery is depleted most patients undergo generator replacement (GR) even in the absence of persistent ICD indication. The aim of this study was to assess the incidence of ventricular arrhythmias and the overall prognosis of patients with and without persistent ICD indication undergoing GR. Predictors of 1-year mortality were also analyzed. METHODS AND RESULTS: Patients with structural heart disease implanted with primary prevention ICD undergoing GR were included. Patients were stratified based on the presence/absence of persistent ICD indication (left ventricular ejection fraction ≤35% at the time of GR and/or history of appropriate ICD therapies during the first generator’s life). The study included 371 patients (82% male, 40% with ischemic heart disease). One third of patients (n=121) no longer met ICD indication at the time of GR. During a median follow-up of 34 months after GR patients without persistent ICD indication showed a significantly lower incidence of appropriate ICD shocks (1.9% versus 16.2%, P<0.001) and ICD therapies. 1-year mortality was also significantly lower in patients without persistent ICD indication (1% versus 8.3%, P=0.009). At multivariable analysis permanent atrial fibril-lation, chronic advanced renal impairment, age >80, and persistent ICD indication were found to be significant predictors of 1-year mortality. CONCLUSIONS: Patients without persistent ICD indication at the time of GR show a low incidence of appropriate ICD therapies after GR. Persistent ICD indication, atrial fibrillation, advanced chronic renal disease, and age >80 are significant predictors of 1-year mortality. Our findings enlighten the need of performing a comprehensive clinical reevaluation of ICD patients at the time of GR.