Exercise Stress Testing in Evaluation of Aortocoronary Bypass Surgery

Abstract

Graded exercise treadmill tests (ET) were performed on 123 patients who had undergone aortocoronary bypass surgery. All had angina preoperatively (preop) and 77% were in Class III or IV for angina. Postoperatively (postop), 68% were free of angina. Eighty-three patients had ST-segment changes of 0.1 mV or greater during stress preop (positive), 38 of which (46%) converted to electrocardiographically negative postop. Among the 30 patients (36%) remaining positive during stress postop, 19 (63%) were angina free despite ST-segment depression during stress. Among the 17 patients with negative ET preop, there were no conversions to positive postop. Twenty-three patients had undetermined ET preop; 13 remained undetermined postop, 4 were positive and 6 were negative. Patients experiencing a perioperative myocardial infarction more frequently had a negative postop ET. Among 27 selected patients undergoing postop angiography, there was good correlation between relief of symptoms and successful myocardial revascularization. This study demonstrates that dramatic improvement in angina after aortocoronary bypass surgery can be objectively substantiated in most patients. Subjective symptoms of angina are frequently absent during myocardial ischemia postop, emphasizing the importance of exercise testing in objective evaluation of surgical results.