Usefulness of residual ischemic myocardium within prior infarct zone for identifying patients at high risk late after acute myocardial infarction

Kenneth A Brown; Robert M Weiss; John P Clements; Frans J.Th Wackers

doi:10.1016/0002-9149(87)90975-1

This study examines the prognostic implications of ischemia within the territory of a prior acute myocardial infarction (AMI) vs ischemia at a distance, which develops late after AMI. Sixty-one consecutive patients who underwent both exercise thallium 201 (TI-201) imaging and cardiac catheterization for evaluation of chest pain that developed after discharge from the hospital for AMI form the study group. Mean interval between infarction to the TI-201 study was 10 ± 17 months. Initial and 2-hour delay TI-201 images were analyzed quantitatively to determine the presence and location (within vs outside the prior infarct zone) of TI-201 redistribution, a marker of ischemic viable myocardium. TI-201 imaging results were separated into 3 groups based on presence and location of TI-201 redistribution: no significant TI-201 redistribution was found in 16 patients; in 29, TI-201 redistribution was confined to the infarct zone; and in 16, TI-201 redistribution was outside the infarct zone. Stepwise multivariate logistic regression analysis was used to examine the comparative ability of TI-201 results and other patient variables to predict cardiac events. For total cardiac events (cardiac death, recurrent nonfatal AMI, unstable angina and coronary revascularization), both the presence of any TI-201 redistribution and multivessel angiographic coronary artery disease were significant predictors. However, when coronary revascularization was excluded as an end-point, TI-201 redistribution limited to the prior infarct zone was the only significant predictor of cardiac events. All 8 cardiac events occurred in patients with TI-201 redistribution limited to the infart zone. When only “hard” endpoints of cardiac death or recurrent nonfatal AMI were considered, TI-201 redistribution limited to the prior infarct zone remained the only significant predictor. Finally, significant multivariate predictors of coronary revascularization included TI-201 redistribution outside the infarct zone and the presence of prior inferior wall AMI. Among patients presenting with chest pain late after AMI, evidence of residual jeopardized viable myocardium within a prior infarct zone, based on exercise TI-201 imaging results, identifies patients at high risk for important cardiac events. Conversely, patients without demonstrable significant ischemia have an excellent prognosis. Patients with evidence of ischemia outside the infarct zone will probably undergo coronary revascularization, precluding conclusions regarding their natural history.

Usefulness of residual ischemic myocardium within prior infarct zone for identifying patients at high risk late after acute myocardial infarction

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