Measurement of coronary calcium scores by electron beam computed tomography or exercise testing as initial diagnostic tool in low-risk patients with suspected coronary artery disease.

Abstract

We determined the efficiency of a screening protocol based on coronary calcium scores (CCS) compared with exercise testing in patients with suspected coronary artery disease (CAD), a normal ECG and troponin levels. Three-hundred-and-four patients were enrolled in a screening protocol including CCS by electron beam computed tomography (Agatston score), and exercise testing. Decision-making was based on CCS. When CCS>or=400, coronary angiography (CAG) was recommended. When CCS<10, patients were discharged. Exercise tests were graded as positive, negative or nondiagnostic. The combined endpoint was defined as coronary event or obstructive CAD at CAG. During 12+/-4 months, CCS>or=400, 10-399 and <10 were found in 42, 103 and 159 patients and the combined endpoint occurred in 24 (57%), 14 (14%) and 0 patients (0%), respectively. In 22 patients (7%), myocardial perfusion scintigraphy was performed instead of exercise testing due to the inability to perform an exercise test. A positive, nondiagnostic and negative exercise test result was found in 37, 76 and 191 patients, and the combined endpoint occurred in 11 (30%), 15 (20%) and 12 patients (6%), respectively. Receiver-operator characteristics analysis showed that the area under the curve of 0.89 (95% CI: 0.85-0.93) for CCS was superior to 0.69 (95% CI: 0.61-0.78) for exercise testing (P<0.0001). In conclusion, measurement of CCS is an appropriate initial screening test in a well-defined low-risk population with suspected CAD.