Incidence, pathophysiology and prognosis of exercise-induced sustained ventricular tachycardia associated with healed myocardial infarction.

Of 150 consecutive patients with sustained monomorphic ventricular tachycardia (VT) (n = 116) or ventricular fibrillation (VF) (n = 34) late after acute myocardial infarction, 17 had reproduction of their sustained monomorphic VT during exercise testing. Data from these patients (group I) were compared with data from patients without exercise-induced VT (group II). No statistical difference was found between groups I and II with relation to age, sex, number of vessels with greater than 70% stenosis, left ventricular ejection fraction, number of previous myocardial infarctions, inducibility during programmed stimulation and total mortality during follow-up. In group I, only 1 patient (6%) developed ST depression during exercise compared with 47 patients (35%) in group II (p less than 0.01). After a 34-month mean follow-up, 6 patients in group I (35%) and 18 patients in group II (13%) died suddenly (p = 0.02). It is concluded that sustained monomorphic VT is reproduced during exercise in only 11% of patients with spontaneous late sustained monomorphic VT or VF. Electrocardiographic findings do not support ischemia as a triggering mechanism of exercise-induced sustained monomorphic VT. Patients with exercise-induced sustained monomorphic VT have a high incidence of sudden death.