Benefits of implantable defibrillators are overestimated by sudden death rates and better represented by the total arrhythmic death rate.

Benefits of the implantable defibrillator on survival were studied in 56 consecutive patients (concomitant coronary bypass or arrythmia surgery in 15) during an 8 year period between 1982 and 1990. During a follow-up period of 29 +/- 25 months, six patients had a sudden death and eight patients had a nonsudden cardiac death. Nonsudden cardiac deaths included three surgical deaths (death within 30 days after the surgery; two in patients without and one in a patient with concomitant cardiac surgery), one arrhythmia-related nonsudden death (death within 24 h after an arrhythmic event despite initial termination of the arrhythmia by the implantable defibrillators) and four nonarrhythmic cardiac deaths. The actuarial survival rate free of events at 1, 2 and 3 years was 96%, 96% and 92%, respectively, for sudden death, 91%, 91% and 87% for sudden death and surgical mortality and 89%, 89% and 85% for total arrhythmic death (sudden death, surgical mortality and arrhythmia-related nonsudden death). Thus, in patients treated with an implantable defibrillator, 1) the rate of sudden death is low (8% at 3 years); 2) 50% of nonsudden cardiac deaths are causally related to arrhythmia (surgical mortality or arrhythmia-related nonsudden death); 3) the total arrhythmic death rate is substantially higher than the sudden death rate; and 4) benefits of an implantable defibrillator are overestimated by reported sudden death and nonsudden cardiac death rates. The benefits may be better represented by the total arrhythmic death and nonarrhythmic cardiac death rates.