SUMMARYGraded exercise stress tests performed on 650 consecutive patients with proven or suspected coronary disease undergoing evaluation by cardiac catheterization were correlated with clinical, hemodynamic, and angiographic findings. Among 451 patients with significant coronary stenosis, 332 (74%) had interpretable stress tests and 65% of these were positive (sensitivity). The rate of "false positives" was 8%.The clinical syndrome of typical angina identified significant coronary disease in 89% of the patients, and 58% of that group had a positive exercise test defined by objective electrocardiographic criteria.Patients were not eliminated from this study because of recent digitalis ingestion. Although a higher frequency of uninterpretable exercise tests was found in this group (40%), the test results reflected more severe coronary disease. None of the patients with "false positive" tests were taking digitalis. It is concluded that recent digitalis ingestion should not be considered a contraindication for exercise stress testing.Among the patients with interpretable exercise tests, the angiographic severity of coronary artery disease correlates strongly with the frequency of positive tests (40%, 66%, and 76%, with 70% or greater occlusion of one, two or three vessels respectively). Left main coronary stenosis of 70% or greater was associated with more severe ST segment changes, inability to achieve target heart rate during stress, and a lower maximum heart rate during exercise. The angiographic occurrence of collateral vessels was related to the extent of coronary disease and was associated with a higher percentage of positive exercise tests; no protective effect of collateral circulation could be demonstrated. Patients with abnormal resting hemodynamics or left ventricular asynergy had no significant difference in the frequency of positive tests after adjustment for the angiographic severity of disease.
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.
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