PATHOPHYSIOLOGY AND NATURAL HISTORY MYOCARDIAL INFARCTION Prognostic significance of ventricular tachycardia and fibrillation induced at programmed stimulation

The relative prognostic significance of ventricular tachycardia and ventricular fibrillation inducible at programmed stimulation within 1 month of acute myocardial infarction was compared in a prospective study of 403 clinically well survivors of transmural infarction who were 65 years old or younger. The prognostic significance of delayed potentials on the signal-averaged electrocardiogram was also examined in a subset of 306 patients without bundle branch block. Among the study patients, 20% had inducible ventricular tachycardia, 14% had inducible ventricular fibrillation, and 66% had no inducible arrhythmias. The 2 year probability of remaining free from cardiac death or nonfatal ventricular tachycardia or fibrillation was 0.73 for those with inducible ventricular tachycardia, 0.93 for those with inducible ventricular fibrillation, and 0.92 for those with no inducible arrhythmias. The cycle length of inducible ventricular tachycardia was 230 msec or more in 70% of the patients with inducible tachycardia who died. Of the patients studied by signal-averaged electrocardiography, 26% had delayed potentials. At 2 years, the probability of remaining free from cardiac death or nonfatal ventricular tachycardia or fibrillation was 0.73 for patients with delayed potentials and 0.95 for patients with no delayed potentials. There was a significant correlation (p < .001) between the presence of delayed potentials and the ability to induce ventricular tachycardia. In conclusion, in survivors of recent infarction who have not had spontaneous ventricular tachycardia or fibrillation, inducible tachycardia (but not inducible fibrillation) at programmed stimulation predicts a significant risk of death or spontaneous tachycardia or fibrillation. A similar risk is found for patients with delayed potentials on the signal-averaged electrocardiogram. Circulation 74, No. 4, 731-745, 1986. A MAJORITY of patients with spontaneous ventricular tachycardia or fibrillation late after myocardial infarction have inducible sustained ventricular tachyarrhythmias on programmed stimulation'"8 or delayed potentials detectable in the ST segment of the signalaveraged eletrocardiogram.9-13 However, it is only recently that the prognostic implications of inducible From the Cardiology Unit, Westmead Hospital, Sydney, Australia. Supported by grants from the National Health and Medical Research Council of Australia and the Life Insurance Medical Research Fund of Australia and New Zealand. Address for correspondence: Dr. J. B. Uther, M.D., F.R.A.C.P., Cardiology Unit, Westmead Hospital, Westmead, NSW, 2154, Australia. Received April 22, 1985; revision accepted July 17, 1986. Vol. 74, No. 4, October 1986 sustained ventricular tachyarrhythmias'>'6 and delayed potentials'7 18 have been noted in survivors of recent myocardial infarction who have not had spontaneous late ventricular tachycardia or fibrillation. To date, there have been no studies on the relationship of the morphology of the induced arrhythmia to prognosis, and the relative prognostic significance of inducible ventricular tachyarrhythmias and delayed potentials has not been examined. The present study was designed to assess the relative significance of inducible ventricular tachycardia vs inducible ventricular fibrillation with respect to prediction of mortality and spontaneous ventricular tachycardia and fibrillation in survivors of recent myocardial 731 by gest on July 5, 2017 http://ciajournals.org/ D ow nladed from