Survival in Patients with Depressed Left Ventricular Function Treated by Implantable Cardioverter Defibrillator

Abstract

Mortality in patients with cardiovascular disease is generally due to pump failure or lethal ventricular arrhythmias. In patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) and poor left ventricular (LV) function the death rate is particularly high. The overall incidence of premature arrhythmic death rate in patients with poor LV function is not totally clear. Since implantable cardioverter defibrillator (ICD) could prevent arrhythmic death in any population, we proceeded to analyze mortalities in patients with poor LV function who received ICD. Among a total of 200 consecutive patients receiving ICD at our institution, 68 (34%) had LV ejection fraction (LVEF) of less than 30%. Thirty-one of these (45%) experienced appropriate ICD discharges and 17/31 (55%) had multiple shocks. Survival curves in this population revealed a 5 year projected overall survival of 11% whereas an actual survival was 60%. Even those who ultimately died from nonsudden causes, life was prolonged by ICD in a significant number of cases. Based upon these findings it is concluded that ICD has a major impact on survival in patients with poor LV function suggesting that many of these patients die prematurely from arrhythmia causes.