Coronary calcifications in the detection of coronary artery disease and comparison with electrocardiographic exercise testing. Results from the National Heart, Lung, and Blood Institute's type II coronary intervention study.

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Abstract
The limitations of the exercise ECG as a screening test for coronary artery disease (CAD), particularly in asymptomatic patients were noted. To improve the sensitivity and predictive accuracy of noninvasive screening studies, the results of cardiac fluoroscopy (to detect coronary calcifications) in conjunction with ECG exercise testing were analyzed to detect CAD. These tests were used to screen patients for participation in the NHLBI [National Heart, Lung, and Blood Institute] 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). The predictive accuracy of a positive test for identifying lesions .gtoreq. 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 .gtoreq. 50-82% (P < 0.05). Among symptomatic patients (n = 61), sensitivity for detecting lesions .gtoreq. 50% increased from 40% for ECG exercise testing alone to 65% when fluoroscopic results were also considered. Either test used alone has a low predictive accuracy for detecting lesions .gtoreq. 50% in asymptomatic subjects and a low sensitivity in symptomatic subjects. Predictive accuracy is significantly improved in asymptomatic type II patients when both tests are positive. Sensitivity for detecting lesions .gtoreq. 50% in symptomatic type II patients is enhanced significantly by a combination of 2 tests rather than either 1 alone. The presence of coronary calcifications indicates some level of underlying coronary disease with a high predictive accuracy (86%).