Influence ofImplantable Cardioverter- Defibrillators on theLong-term Prognosis of Survivors ofOut-of-Hospital Cardiac Arrest

Background. Survivors ofout-of-hospital cardiac arrest notassociated withacutemyocardial infarction areathighrisk forrecurrent cardiac arrest andsuddencardiac death. Theimpact oftheimplantable cardioverter-defibrillator on long-term prognosis inthese patients isuncertain. Methods andResults. Threehundred thirty-one survivors ofout-of-hospital cardiac arrest (age, 56±13.7 years) underwent electrophysiologically guided therapy. Implantable defibrillators wereplaced in150patients (453%o), and181patients (54.7%o) received pharmacological and/or surgical therapy alone. Left ventricular ejection fraction was 35.2±16.6% indefibrillator recipients and453±18.2% innondefibrillator patients. Medianpatient follow-up was 24months inthedefibrillator groupand46months inthenondefibrillator group.Ina proportional hazards model, theindependent predictors oftotal cardiac mortality were left ventricular ejection fraction ofless than0.40(relative risk, 4.55; 95%confidence interval, 2.44to8.33; P=.0001), absence ofan implantable defibrillator (relative risk, 2.70; confidence interval, 1.41to5.00, P=.017), andpersistence ofinducible sustained ventricular tachycardia (relative risk, 1.84; 95%confidence interval, 0.97 to3.49; P=.045). The1-and5-year probabilities ofsurvival free ofcardiac mortality inpatients withleft ventricular ejection fraction ofless than0.40 were943%and69.6%o with adefibrillator and82.1% and 453%without adefibrillator, respectively. Forpatients withleft ventricular ejection fraction of0.40 ormore, the 1- and5-year probabilities ofsurvival free ofcardiac mortality were97.7% and94.61% with adefibrillator and95.4% and86.9%,o without adefibrillator, respectively. Conclusions. Insurvivors ofout-of-hospital cardiac arrest, theimplantable defibrillator isassociated witha reduction incardiac mortality, particularly inpatients withimpaired left ventricular function. (Circulation. 1993;88:1083-1092.)