Arrhythmic death in implantable cardioverter defibrillator patients: a long-term study over a 10 year implantation period

Abstract

Evaluation of cause-specific mortality in a large cohort of unselected implantable cardioverter defibrillator (ICD) recipients. Causes of death of consecutive ICD recipients implanted over a 10 year period were analysed. Overall 822 patients (age 63 +/- 11 years, 80% male, EF 34 +/- 14%, secondary prevention 65%) were followed for 43 +/- 30 months during which time 225 patients died (annual mortality 7.6%). Causes of death were cardiac arrhythmic in 16%, cardiac non-arrhythmic in 39%, non-cardiac vascular in 4%, non-cardiovascular in 27%, and unknown in 13%. Advanced age [relative risk (RR) 1.23 per decades, 95% confidence interval (CI) 1.06-1.43], NYHA class >II (RR 2.27, 95% CI 1.51-3.41), renal failure (RR 1.57, 95% CI 1.15-2.14), use of amiodarone (RR 2.56, 95% CI 1.91-3.43), digitalis (RR 1.87, 95% CI 1.40-2.49), diuretics (RR 1.89, 95% CI 1.35-2.66) were independent predictors of all-cause mortality. Predictors for arrhythmic mortality were NYHA class >II (RR 12, 95% CI 3.69-37.5), spontaneous or inducible VT as indication for ICD therapy (RR 2.53, 95% CI 1.06-6.05), and use of amiodarone (RR 3.95, 95% CI 2.02-7.75). In this unselected group of ICD recipients, at least 16% of patients died from arrhythmic causes. Risk factors associated with arrhythmic mortality were a history of spontaneous or inducible VT, higher NYHA class, and amiodarone use.