PROVOCABLE ISCHEMIA FOLLOWING INFERIOR MYOCARDIAL-INFARCTION

Patients with anterior ST-segment depression associated with acute inferior myocardial infarction have been shown to have larger infarctions with more postinfarction complications than those without these changes. However, the extent and location of postinfarction ischemia in these two groups have not been adequately assessed. We evaluated 32 patients admitted with ECG evidence of first inferior myocardial infarction for the presence (group I) of absence (group II) of anterior ST-segment depression on their admission ECG. Low-level thallium-201 exercise tests were obtained prior to discharge and evaluated for the presence and location of exercise-induced ischemia. Exercise parameters, including duration, ECG evidence of ischemia, or induced angina were not different between the two groups of patients. Analysis of thallium-201 images on a regional basis (anteroseptal, inferior, apical, and lateral) revealed no difference in distribution of defects between groups I and II. A much higher incidence of ischemia by thallium-201 defects (79% in group I; 78% in group II) than by ECG criteria (21% in group I; 11% in group II) was found. We conclude that the presence of anterior ST-segment depression on the initial ECG in patients with inferior myocardial infarction does not predict the location, extent, or degree of provocable ischemia detected by low-level postinfarction thallium-201 exercise testing.