Eleven consecutive patients with idiopathic dilated cardiomyopathy and spontaneous, sustained ventricular tachycardia (VT) of uniform morphology underwent programmed ventricular stimulation and serial antiarrhythmic drug testing. The mean ejection fraction was 30 +/- 6.4%. Sustained VT was induced by programmed electrical stimulation in all 11 patients. A mean of 3.7 +/- 2.4 antiarrhythmic drugs were evaluated by programmed stimulation, including at least one experimental agent in eight patients. In nine of 11 patients VT remained inducible on all drug therapy. During a mean follow-up period of 21 +/- 14 months there were four sudden deaths and two patients with recurrences of VT. In all six patients with sudden death or recurrence of VT, the arrhythmia remained inducible on drug therapy. Three patients who died suddenly had a hemodynamically stable, induced tachycardia on antiarrhythmic therapy. Of eight patients treated with amiodarone, only two were successfully treated. We conclude that in patients with sustained VT and idiopathic dilated cardiomyopathy, VT can be induced by programmed electrical stimulation. VT will usually remain inducible on antiarrhythmic therapy, and sudden death can occur despite slowing and improved tolerance of the induced arrhythmia. Amiodarone may have limited efficacy, and more aggressive therapy, such as surgery or implantation of an automatic internal defibrillator, should be considered in this patient population.