Ninety-one consecutive patients with angiographically documented spasm who performed a bicycle stress test within one week before diagnostic coronary angiography are studied. Stress test induced ST elevation in 8 patients (9%), ST depression in 37 (41%) and no ST shifts in 46 (50%). ST response to exercise did not correlate with any of the clinical variables assessed except for coronary anatomy. ST depression was a highly specific sign of underlying coronary lesions, with a high positive predictive value (89%). Patients were stratified according to the type of angina and their post-test probability of significant coronary disease was calculated following Bayes' theorem. The post-test likelihoods of significant coronary stenosis (positive and negative test, respectively) were: 82 and 37% for patients with angina at rest; 90 and 53% for those with effort angina, and 98 and 85% for those with mixed angina.
In conclusion: 1) stress testing in patients with coronary spasm correlates well with coronary anatomy; 2) ST depression strongly suggests the presence of underlying coronary stenosis; 3) stress testing is especially useful in patients with angina exclusively at rest.