Abstract 470: Ultrasound Carotid Plaque Features, Cardiovascular Disease Risk Factors and Events: the Multi-Ethnic Study of Atherosclerosis

Abstract

Background: Grayscale ultrasound atherosclerotic plaque characteristics may predict cardiovascular disease (CVD) events, though they have not been investigated in a large primary prevention cohort. This study determined if CVD risk factors were associated with carotid plaque ultrasound characteristics and if these characteristics could predict future coronary heart disease (CHD) and stroke/transient ischemic attack (TIA) events in a multi-ethnic cohort free of known CVD at baseline. Methods: We measured carotid artery total plaque area (TPA) and grayscale carotid plaque features (grayscale median, black areas, and discrete white areas) at baseline in participants of the Multi-Ethnic Study of Atherosclerosis that had B-mode carotid ultrasound examinations. There were 2205 participants with images available for TPA analyses and 1703 with images available for grayscale analyses. Multivariable linear regression analysis was used to examine relationships between baseline ultrasound carotid plaque features and CVD risk factors. Cox proportional hazards models were used to assess their ability to predict incident CHD and stroke/TIA events over an average follow-up of 13.3 years. The predictive characteristics of TPA and carotid plaque features were compared to carotid plaque score and coronary artery calcification (CAC) score. Results: Participants were mean (standard deviation) 65.4 (9.6) years old, 49% male, 39% White, 28% Black, 22% Hispanic, and 11% Chinese. Mean TPA (27.7 [24.7] mm 2 ), but not grayscale plaque features, were associated with several CVD risk factors. In risk factor-adjusted models, TPA was the only plaque feature that predicted incident CHD events (HR 1.23; 95% CI 1.11-1.36; p<0.001) with C-statistics for CHD that were similar to carotid plaque score, but lower than CAC score. TPA did not independently predict stroke/TIA events. No gray scale plaque feature predicted future CHD or stroke/TIA events. Conclusions: In middle-aged individuals free of known CVD, carotid TPA was associated with CVD risk factors and predicted incident CHD events while grayscale plaque features did not. For CHD, predictive characteristics of TPA were similar to carotid plaque score but lower than CAC score.