Exercise tests in patients with severe angina pectoris: an angiographic correlation.

Graded submaximal ergometric tests were peformed on 60 patients who suffered from clinically severe angina pectoris, and the results were correlated with their coronary angiograms. The test was positive in 44, negative in 9, and undetermined in 7 patients (defined as failure to reach the target heart rate without ischemic ST changes). Among patients with positive tests, 42 (95%) had obstruction of one to three coronary vessels. Among patients with negative tests, only 3 had significant coronary disease (sensitivity 93%). While all patients suffered clinically from severe "angina pectoris," 8 (15%) had insignificant CAD, and among them 6 had a negative and 2 a false-positive exercise response (specificity 75%). Although ST depression was a good indicator of CAD, its degree did not parallel the severity of the lesions. The peak heart rate on exercise of patients with ischemic ST changes was lower than their target heart rate, suggesting that the heart rate at which ST changes occur constitutes in itself a good indicator of severity. Among the 7 patients with undetermined tests, CAD was found in 6. In these patients the absence of ST changes may be ascribed to extensive myocardial fibrosis, and the only clue to CAD resides in the negative chronotropic response to exercise. Although exercise testing does not always distinguish between normal and CAD patients, it nevertheless constitutes a valuable noninvasive technique for the detection of the high-risk patients.