CORONARY CALCIFICATIONS IN THE DETECTION OF CORONARY-ARTERY DISEASE AND COMPARISON WITH ELECTROCARDIOGRAPHIC EXERCISE TESTING - RESULTS FROM THE NATIONAL HEART, LUNG, AND BLOOD INSTITUTES TYPE-II CORONARY INTERVENTION STUDY

Recent studies have noted the limitations of the exercise ECG as a screening test for coronary artery disease (CAD), particularly in asymptomatic patients. To improve the sensitivity and predictive accuracy of noninvasive screening studies, we analyzed the results of using cardiac fluoroscopy (to detect coronary calcifications) in conjunction with electrocardiographic exercise testing to detect CAD. We used these tests to screen patients for participation in the NHLBI Type II Coronary Intervention Study. The predictive accuracy of a positive test for identifying any degree of coronary artery stenosis among asymptomatic patients (n=93) was 86% for cardiac fluoroscopy and 69% for exercise testing (p=0.07). However, the predictive accuracy of a positive test for identifying lesons ≥50% in this same population was only 46% for cardiac fluoroscopy and 36% for exercise testing. The combination of a positive exercise test and positive cardiac fluoroscopy increased the predictive accuracy for lesions ≥50% to 82% (p<0.05). Among symptomatic patients (n=61), sensitivity for detecting lesions ≥50% increased from 40% for electrocardiographic exercise testing alone to 65% when fluoroscopic results were also considered. We conclude that either test used alone has a low predictive accuracy for detecting lesions ≥50% in asymptomatic subjects and a low sensitivity in symptomatic subjects. However, 1) predictive accuracy is significantly improved in asymptomatic type II patients when both tests are positive; 2) sensitivity for detecting lesions ≥50% in symptomatic type II patients is enhanced significantly by a combination of two tests rather than either one alone; and 3) the presence of coronary calcifications indicates some level of underlying coronary disease with a high predictive accuracy (86%).