Prognosis of patients with ventricular tachycardia or fibrillation and a normal electrophysiologic study. The outcome of 26 patients with sustained ventricular tachycardia (n = 16) or ventricular fibrillation (n = 10) and no inducible ventricular tachycardia (less than or equal to 10 beats) by baseline programmed stimulation was studied. Coronary artery disease was present in 14 patients, dilated cardiomyopathy was seen in seven, valvular heart disease was present in two, and no apparent cardiac abnormalities were found in three. The mean left ventricular ejection fraction was 53 +/- 14%. During the follow-up period of 24 +/- 16 months, actuarial survival rates at 1 and 2 years were 95% and 89% for sudden death and 95% and 83% for total cardiac death, respectively. No patients with a known ejection fraction greater than 30% died suddenly during the follow-up. Noninducibility by programmed stimulation in patients with sustained ventricular tachycardia or fibrillation is associated with a relatively preserved ventricular function. It may predict a low risk of sudden death in patients with preserved ventricular function. 