This usually consists of a drive train at a constant paced cycle length followed by one, two, or three extra stimuli. The role of invasive electrophysiological study for risk stratification in asymptomatic patients after myocardial infarction remains controversial. In about 20 percent of such patients, sustained monomorphic ventricular postinfarction tachycardia can be induced using programmed stimulation, and in an additional 10 to 15 percent, ventricular fibrillation can be produced. During follow-up, arrhythmic events occur in five percent of the noninducible patients, in 10 percent of patients with inducible ventricular fibrillation, and in 50 percent of patients with inducible ventricular tachycardia. Although electrophysiological study has reasonable sensitivity for prediction of subsequent arrhythmic events, the positive predictive value of the test is probably no better than that of the signal-averaged ECG, especially when the latter is combined with measurements of left ventricular systolic function and quantification of ambient ectopy.
Electrophysiological study is invasive and relatively expensive.
Moreover, there is no evidence to suggest that treatment of this group of patients with antiarrhythmic drugs improves survival. Thus, it is difficult to justify routine electrophysiological testing in asymptomatic patients after myocardial infarction. Electrophysiological testing is of uncertain value for stratification of risk in patients with nonischemic cardiomyopathy and asymptomatic ventricular ectopy. In this population, induction of sustained monomorphic ventricular tachycardia is infrequent and does not appear to be predictive of subsequent sudden cardiac death.