The purpose of this study was to evaluate the prevalence of occult coronary artery disease (CAD) with coronary computed tomography angiography (CTA) to characterize plaque composition and to evaluate the potential of this new technology to impact risk stratification in asymptomatic middle-aged subjects.

There is a paucity of information regarding the role of CTA for the detection of occult CAD in asymptomatic individuals.

We consecutively enrolled 1,000 middle-aged asymptomatic subjects (age 50 ± 9 years, 63% men) who underwent CTA (64-slice multidetector row computed tomography) as part of a general health evaluation.

Atherosclerotic plaques were identified in 215 (22%, 2 ± 1 segments/subject) individuals; 40 individuals (4%) had only noncalcified plaques. Fifty-two (5%) subjects had significant (≥50%) diameter stenosis and 21 (2%) had severe (≥75%) stenosis. Thirteen (25%) and 30 (58%) subjects with significant stenosis were classified into National Cholesterol Education Program low-risk and mild coronary calcification (coronary artery calcium scores <100), respectively. Midterm follow-up (17 ± 2 months) revealed 15 cardiac events only in those with CAD on CTA: 1 unstable angina requiring hospital stay and 14 revascularization procedures. Most (87%) events occurred within 90 days of index CTA.

The prevalence of occult CAD in apparently healthy individuals was not negligible, although their midterm prognosis was good. CTA has a potential to provide a better insight about the occult CAD in this population. However, on the basis of our results and considering present radiation exposure data, we cannot recommend that CTA be used as a screening tool for this population at this point. (Subclinical COronary Atheroscleorosis Updated With Coronary cT Angiography [SCOUT Study]; NCT00431860)