To assess the prognostic value of the response to programmed ventricular stimulation in selected post-acute myocardial infarction (AMI) patients identified at risk of sudden death and spontaneous sustained ventricular tachycardia (VT) (arrhythmic events) by noninvasive, highly sensitive testing, 286 consecutive patients were evaluated prospectively and followed for 12 months. One hundred three patients (group 1) with either left ventricular ejection fraction < or = 40% or ventricular late potentials or spontaneous complex ventricular arrhythmias were considered at risk of late arrhythmic events and eligible for programmed ventricular stimulation; the remaining 183 patients (group 2) were discharged without any further evaluation. Electrophysiologic study was performed 11 to 20 days after AMI utilizing up to 2 extrastimuli and rapid ventricular burst pacing. At the end of the follow-up period, 10 patients in group 1 and 2 in group 2 died of cardiac causes; in addition, 10 patients in group 1 and 1 in group 2 had arrhythmic events. Sustained monomorphic VT was the only inducible arrhythmia related either to cardiac death (p <0.0005) or to arrhythmic events (p <0.0001). It was induced in 11 patients (3 died suddenly, and 3 had spontaneous VT). Multivariate analysis showed that such arrhythmia was the strongest independent predictor of arrhythmic events (F = 9.76; p <0.0001). In the entire study population, it allowed identification of patients at risk, with a sensitivity, specificity, and positive predictive value of 55%, 99%, and 67%, respectively. We conclude that programmed ventricular stimulation performed in selected post-AMI patients, utilizing a moderately aggressive stimulation protocol, is a specific but less sensitive procedure for predicting arrhythmic events; the induction of sustained monomorphic VT allows the accurate identification of patients who may profit by prophylactic antiarrhythmic therapy.