QUANTITY OF CORONARY-ARTERY CALCIUM DETECTED BY ELECTRON-BEAM COMPUTED-TOMOGRAPHY IN ASYMPTOMATIC SUBJECTS AND ANGIOGRAPHICALLY STUDIED PATIENTS

Objective: To determine the prevalence and quantity of coronary artery calcium (CAC) in asymptomatic subjects from the general population, to identify asymptomatic subjects without risk factors for coronary artery disease (CAD) with CAC scores in the top quartile of the distribution, and to compare CAC scores in patients who underwent angiography with percentiles in asymptomatic subjects of the same age and sex. Design: We studied two samples from Rochester, Minnesota, which consisted of 772 asymptomatic subjects from the general population and 145 patients who underwent angiography, all of whom were 20 to 59 years of age. Methods: Asymptomatic subjects were classified on the basis of their CAD risk profile. All subjects in both study samples underwent electron beam computed tomography. Age- and sex-specific calcium score percentiles were calculated in the asymptomatic sample. Results: CAC prevalence in the asymptomatic subjects was lower in female than in male subjects and increased with advancing age. Of the asymptomatic sample, 8% had a low-risk profile with calcium scores in the top quartile of the distribution. More patients than expected in the angiography sample had calcium scores above the 50th through 95th score percentiles. Conclusion: The quantity of CAC was substantially increased in patients who underwent angiography. Subjects with large amounts of CAC but without known CAD risk factors may be a valuable subset of the population to investigate for previously unidentified CAD risk factors.