Clinical, electrophysiologic and follow-up data were analyzed for 108 patients with aborted sudden death. The mean follow-up interval was 2 years. All patients underwent baseline drug-free invasive electrophysiologic studies. Seventy-five patients (group I) had inducible ventricular arrhythmias (including nonsustained and sustained ventricular tachycardia and ventricular fibrillation) and 33 patients (group II) had no inducible arrhythmias. Noninducibility was not predictive of a favorable outcome, because the incidence of both sudden death and recurrent ventricular tachycardia was similar in the two groups. Treatment guided by electrophysiologic testing was used in 17 patients; in 13 (17%) in group I arrhythmias became noninducible, and in 4 (5%) sustained ventricular arrhythmias became nonsustained after administration of conventional drugs. There was a significantly higher incidence of sudden death and recurrent ventricular tachycardia in the 4 patients with inducible arrhythmias (n = 3, 75%) compared with the 13 patients whose arrhythmias were noninducible (n = 2, 15%) (p less than 0.05). For the group as a whole, 11% died suddenly and 15% had recurrence of ventricular tachycardia. Sixty-four patients were treated with amiodarone and, of these, four (6%) died suddenly during the follow-up period and nine (14%) had recurrent ventricular tachycardia. Ventricular arrhythmias could be induced in 69% of patients with aborted sudden death but inducibility could be suppressed in only 20% of them. The role of therapy guided by electrophysiologic testing could therefore not be fully assessed. The findings reveal a significant recurrence rate of symptomatic, potentially life-threatening ventricular arrhythmias in medically treated patients with aborted sudden death.(ABSTRACT TRUNCATED AT 250 WORDS)