Can exercise electrocardiography and thallium-201 myocardial imaging exclude the diagnosis of coronary artery disease?: Bayesian analysis of the clinical limits of exclusion and indications for coronary angiography

Abstract

The objective of this study was to determine whether exercise electrocardiography can be combined with thallium-201 myocardial imaging and the clinical history to exclude the diagnosis of coronary artery disease. All 96 patients in this study were referred for coronary angiography because of chest pain but did not have prior myocardial infarction; 52 percent had coronary artery disease. Each patient's chest pain was classified as either typical or not typical of angina pectoris. Negative tests with inadequate exercise stress (less than 85 percent of the age-predicted maximal heart rate) and combined tests with discordant results (either exercise electrocardiography or thallium imaging positive and the other test negative) were judged nondiagnostic. Nondiagnostic tests that contributed most to the uncertainty of results were classified separately: exercise electrocardiogram, 35 patients; thallium imaging, 9 patients; and combined exercise electrocardiogram and thallium imaging, 50 patients. The ability of each test to rule out coronary artery disease was defined by its predictive error (probability of coronary disease despite a negative test): history of chest pain not typical of angina, 26 percent (11 of 42); exercise electrocardiogram, 22 percent (5 of 23); thallium imaging, 27 percent (6 of 35); and negative findings on both exercise electrocardiogram and thallium imaging, 6 percent (1 of 17). Finally, when only the patients with atypical chest pain were considered, there was zero (0 of 15) predictive error if both tests were negative. Negative exercise electrocardiography and thallium imaging during adequate stress ruled out any coronary artery disease in these patients with considerable reliability (94 percent) and excluded multivessel disease with even greater reliability. These exclusion tests for coronary artery disease were most reliable in patients in whom the clinical diagnosis of coronary artery disease was least likely, as defined by Bayes' theorem. It is concluded that there is no perfect noninvasive test to exclude coronary disease in all patient populations; however, coronary angiography is not necessary to rule out the diagnosis of coronary artery disease in patients who'have (1) no clinical indicators of a very high probability of coronary disease, such as typical angina, (2) adequate exercise stress, (3) negative exercise electrocardiogram and (4) negative exercise thallium images.