Ninety-two patients underwent programmed ventricular stimulation 12 +/- 3 days after acute myocardial infarction (AMI) treated with thrombolytic agents (streptokinase, recombinant tissue plasminogen activator, or both). Cardiac catheterization was performed in all patients on admission to hospital and was repeated in 97% of them 13 +/- 5 days later. Sustained ventricular arrhythmias--either tachycardia (VT) or fibrillation--were induced in 20 (22%) patients, with nonsustained VT induced in another 12 (13%). Multivariate analysis was used to identify predictors of induction of sustained VT, with short right ventricular effective refractory period (p = 0.0061), site of AMI (inferior or posterior, p = 0.008), infarct-related artery (right or circumflex coronary artery, p = 0.018), multivessel coronary artery disease (p = 0.043) and male sex (p = 0.028) being significant predictors of sustained VT. Neither successful reperfusion, time to reperfusion, nor residual stenosis in the infarct-related artery was significant. All patients in whom VT was induced were treated with electrophysiologically guided antiarrhythmic therapy. Cardiac mortality after hospital discharge was 1% over 30 +/- 16 months.