Coronary Computed Tomography (CT) Angiography as a Predictor of Cardiac and Noncardiac Vascular Events in Asymptomatic Type 2 Diabetics: A 7‐Year Population‐Based Cohort Study

BACKGROUND Type 2 diabetics are at increased risk for vascular events, but the value of further risk stratification for coronary heart disease (CHD) in asymptomatic subjects is unclear. We examined the added value of coronary computed tomography angiography over clinical risk scores (United Kingdom Prospective Diabetes Study), and coronary artery calcium in a population-based cohort of asymptomatic type 2 diabetics. METHODS AND RESULTS Subjects (n=630) underwent baseline clinical assessment and computed tomography angiography (64-slice scanner). Plaque site, volume, calcific content, and arterial remodeling were recorded using dedicated software. Coronary, macrovascular, and microvascular-related events were assessed over 6.6±0.6 (mean±SD) (range 5.4-7.5) years and all CHD events were adjudicated. Discrimination of CHD events (cardiovascular death, myocardial infarction, unstable angina, or new-onset angina requiring intervention) (n=41) was improved by addition of total plaque burden to the clinical risk and coronary artery calcium scores combined (C=0.789 versus 0.763, P=0.034) and further improved by addition of an angiographic score (C=0.824, P=0.021). Independent predictors of a CHD event were United Kingdom Prospective Diabetes Study risk score (hazard ratio 1.3 per 10% 10-year risk, P=0.003) and the angiographic score (hazard ratio 3.2 per quartile, P<0.0001). Classification was improved over that by United Kingdom Prospective Diabetes Study and coronary artery calcium scores alone (overall net reclassification improvement 0.24). In subjects with coronary plaque (N=500), mild plaque calcification independently predicted a CHD event (hazard ratio 3.0, P=0.02). Computed tomography angiography predicted combined macrovascular but not microvascular-related events. CONCLUSIONS Computed tomography angiography provides additional prognostic information in asymptomatic type 2 diabetics not obtainable from clinical risk assessment and coronary artery calcium alone.