Sudden death is common in patients with severe heart failure, but antiarrhythmic drug therapy has potential risks as well as benefits. Programmed electrical stimulation may offer a means of identifying lower risk patients who are less likely to benefit from antiarrhythmic therapy and who could potentially be spared the risk of adverse drug effects. Therefore 72 consecutive patients referred for management of severe heart failure (left ventricular ejection fraction 0.18 +/- 0.06) were studied. The mean age was 47 +/- 12 years; 45 (61%) patients had idiopathic dilated cardiomyopathy and 24 (33%) had coronary artery disease. Fifty-eight (82%) patients had nonsustained ventricular tachycardia. Following adjustment of vasodilators and diuretics, programmed stimulation was performed from the right ventricular apex with one, two, and three extrastimuli. Sustained ventricular tachycardia was initiated in nine (13%) patients and all received chronic antiarrhythmic drug therapy. During follow-up of 176 +/- 187 days, 1 of 13 patients treated for inducible ventricular tachycardia and 13 of 63 noninducible patients died suddenly (p = 0.20). The actuarial risk of sudden death in the noninducible patients was 13% at 6 weeks and 30% at 6 months. The only independent predictors of sudden death were pulmonary artery systolic pressure greater than 55% mm Hg and a pulmonary capillary wedge pressure with vasodilator therapy greater than 16 mm Hg. Of the 63 noninducible patients, 11 (17%) received long-term antiarrhythmic agents due to atrial fibrillation or referring physician preference, and antiarrhythmic therapy was not associated with a lower risk of sudden death in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)