Usefulness of the automatic implantable cardioverter defibrillator in improving survival of patients with severely depressed left ventricular function associated with coronary artery disease. Clinical outcome was analyzed among a group of 39 consecutive patients with coronary artery disease, left ventricular (LV) ejection fractions less than 30% and arrhythmias that required an automatic implantable cardioverter defibrillator (AICD) in an attempt to better define the role of the device in patients with severely depressed LV function. Twenty-nine (74%) were survivors of out-of-hospital cardiac arrest and 10 (26%) had ventricular tachycardia that was refractory to electrophysiologically guided antiarrhythmic therapy. The study group had the following demographic characteristics: 90% were men, mean age was 64 years (range 41 to 79) and mean LV ejection fraction was 21 +/- 4%. Concomitant pharmacotherapy included antiarrhythmic drugs 31 (79%), vasodilators in 22 (56%) and digoxin in 20 (51%). There was no statistical difference in baseline characteristics between survivors and nonsurvivors. Patients were followed for a mean of 24 months (range 2 to 72) from implantation. The difference between actuarial survival--77% at 1 year and 72% at 2 years--and projected survival without the AICD (patients who survive without appropriate device discharge)--30% at 1 year and 21% at 2 years--was significant (p less than 0.01 and less than 0.05 at 1 and 2 years, respectively). This study suggests that the AICD improves survival in patients with coronary artery disease despite severely depressed LV function. 