Clinical and angiographic correlates of exercise-induced ST-segment elevation. Increased detection with multiple ECG leads

Abstract

ST-segment elevation was observed in 47 of 720 patients who underwent treadmill exercise testing using 14 ECG leads 1 day before coronary arteriography. This abnormality was detected in lead V5 in only 13 of 47 patients (28%) and in lead CM5 in only nine of 47 patients (19%). In 36 patients previous myocardial infarction (27 anterior, nine inferior) was diagnosed on the resting ECG; in all cases the ST-segment elevation during exercise occurred in leads with Q waves. In 34 of 36 patients (94%) a corresponding left ventricular wall motion abnormality was present, usually (33 of 36, 92%) a dyskinetic or akinetic segment. All but two of the 36 patients had a coronary stenosis ≥ 70% in the artery perfusing the involved region. Ten of the 11 patients with no ECG evidence of myocardial infarction had documented variant angina. In all 10 cases ST-segment elevation during exercise occurred in the same ECG leads as during spontaneous resting attacks. All 10 had normal left ventricular angiograms and only three had a coronary stenosis ≥ 70%. A large perfusion defect corresponding to the site of ST-segment elevation and not present at rest was detected in each of the six who had exercise thallium-201 scans. Four patients retested during treatment with nifedipine did not develop angina, ST changes or perfusion defects. These findings suggest that exercise-induced ST-segment elevation is probably caused directly by a segmental wall motion abnormality in patients with previous myocardial infarction, but by coronary artery spasm in patients with variant angina.