BackgroundCoronary artery calcium (CAC) predicts coronary heart disease (CHD) events better than carotid wall plaque presence; however, differences in the utility of CAC burden and carotid plaque burden across the spectrum of cardiovascular disease (CVD) events is unknown.
Methods and resultsCVD, CHD and stroke/transient ischemic attack (TIA) events were evaluated prospectively in a multiethnic cohort without CVD at baseline. Carotid plaque score was determined by the number of ultrasound-detected plaques in the common, bifurcation, and internal carotid artery segments. CAC was detected by computed tomography. Predictive values were compared using Cox proportional hazards models, C-statistics, and net reclassification, adjusting for traditional CVD risk factors. At baseline, the 4955 participants were mean (SD) 61.6 (10.1) years old and 52.8% female; 48.9% had CAC >0 and 50.8% had at least 1 carotid plaque. After 11.3 (3.0) years of follow-up, 709 CVD, 498 CHD, and 262 stroke/TIA events occurred. CAC score compared to carotid plaque score was a stronger predictor of CVD (hazard ratio [HR], 1.78; 95% CI, 1.16-1.98; P<0.001 vs HR, 1.27; 95% CI, 1.16-1.40; P<0.001) and CHD events (HR, 2.09; 95% CI, 1.84-2.38; P<0.001 vs HR, 1.35; 95% CI, 1.21-1.51; P<0.001). CAC score and carotid plaque score were weak predictors of stroke/TIA. CAC score had better reclassification statistics than carotid plaque score, except for stroke/TIA, which had similar predictive values.
ConclusionsCAC score improved prediction, discrimination, and reclassification of CVD and CHD better than carotid ultrasound measures, although prediction and discrimination were similar for stroke/TIA.