Sustained ventricular tachyarrhythmias during the early postinfarction period: electrophysiologic findings and prognosis for survival.

Forty patients with sustained tachycardia occurring 3 to 65 days after myocardial infarction underwent programmed ventricular stimulation within 3 months of the infarction. Patients were characterized clinically by a complicated initial 48 hours of hospitalization for their acute infarction (85% of study group). The development of bundle branch block in association with infarction occurred with an unusually high frequency (32%). Ventricular tachycardia similar in configuration to spontaneous arrhythmia was induced with programmed ventricular stimulation in 33 (83%) of the 40 patients. In 15 (45%) of these 33 patients, additional morphologically distinct ventricular tachycardia not seen clinically was initiated. The induction of ventricular tachycardia was not significantly related to the time after myocardial infarction at which spontaneous ventricular tachycardia was initially observed. Only 20 of the 40 patients are alive after a mean follow-up period of 20 +/- 15 months. Twelve of the 20 deaths were sudden cardiac deaths. Sixteen of the 33 patients with inducible ventricular tachycardia died; 8 of the 16 deaths were sudden. By comparison, four of the seven patients with no inducible ventricular tachycardia died (probability [p] = not significant), all suddenly. The mode of therapy did not influence subsequent survival. It appears that in patients with sustained ventricular tachycardia occurring more than 48 hours after a recent myocardial infarction, ventricular tachycardia similar to that clinically observed can usually be induced by programmed stimulation. In addition, multiple morphologically distinct ventricular tachycardias, some of which have not been previously observed, are frequently induced. Finally, the prognosis for survival is poor, regardless of inducibility or mode of therapy, and may in part be related to a changing arrhythmia substrate.