Analysis of multiple noninvasive test procedures for the diagnosis of coronary artery disease

All noninvasive tests used for the diagnosis of coronary artery disease are imperfect, both in sensitivity and in specificity. Accordingly, we evaluated the accuracy of four different diagnostic tests in various combinations in a population of 43 patients undergoing coronary angiography to determine if accuracy could be improved by multiple testing. These tests included stress electrocardiography for evaluation of exercise-induced ST-segment depression, stress cardio-kymography (CKG) for detection of exercise-induced precordial regional left ventricular dysfunction, stress ²⁰¹thallium scintigraphy for assessment of exercise-induced regional myocardial hypoperfusion, and cardiac fluoroscopy for detection of coronary artery calcification. A total of 46 (27%) of the 172 test responses observed were incorrect relative to angiography. These “false” responses were uniformly distributed over the four test procedures (12 ECG, 11 CKG, 10 ²⁰¹thallium, 13 fluoroscopy). Thus, a single test had a limited predictive accuracy for the detection or exclusion of coronary artery disease. The greater the number of abnormal responses observed in a given patient the greater the predictive accuracy for disease, especially multi-vessel disease. Analysis of various combinations of these procedures revealed substantial differences both in cost of testing and net diagnostic yield. These data suggest that the four procedures employed are functionally independent and highly accurate relative to the diagnosis of coronary artery disease when used in combination. Cost-effectiveness of diagnostic testing might be improved with the use of combinations of the less expensive and more accurate of these tests.