Therapeutic significance of exercise-induced ST-segment elevation in patients without previous myocardial infarction.

Twelve patients with exercise-induced ST-segment elevation without prior myocardial infarction, electrocardiographic evidence of left ventricular hypertrophy or left bundle branch block underwent thallium-201 tomography immediately after exercise and 4 hours later. Coronary angiography and left ventriculography were performed within an average of 8 days of exercise testing. Five patients had repeat exercise thallium-201 tomography after medical therapy or revascularization. All patients had large, reversible perfusion defects (average defect size 33.5 +/- 13%), with 11 of 12 patients having a > or = 25% stress perfusion defect. In 10 patients with atherosclerotic coronary artery disease, the average stenosis of the involved vessel was 93 +/- 9% (range 70 to 100). The electrocardiographic leads with ST-segment elevation predicted the site of reversible hypoperfusion. Two patients had extensive, reversible anterior hypoperfusion due to exercise-induced spasm of minimally stenosed left anterior descending coronary arteries. Follow-up exercise testing in 5 patients showed abolition of reversible hypoperfusion and ST changes after medical therapy or revascularization. In patients without prior myocardial infarction, exercise-induced ST-segment elevation signifies extensive, reversible hypoperfusion that can be abolished by revascularization in patients with critical coronary stenoses and by medical therapy in those with coronary vasospasm.