Abstract 9829: Subclinical Atherosclerosis in Asymptomatic Subjects Referred for Risk Stratification: A Comparison of Carotid Ultrasound, Coronary Artery Calcium Scoring and Coronary Computed Tomography Angiography

Abstract

Introduction: In subjects free of known vascular disease, current guidelines recommend lipid targets according to global risk of cardiovascular events. In select populations, imaging is recommended for refining clinical risk. The purpose of this study was to compare three imaging modalities coronary artery calcium scoring (CACS), carotid ultrasound (US) and coronary computed tomography angiography (CCTA) in a population referred for risk stratification. Hypothesis: We hypothesized that diverse definitions of early atherosclerosis utilized by differing modalities would affect perceived prevalence of subclinical atherosclerosis and consequently, assessment of risk. We sought to determine the degree of concordance among these definitions. Methods: Subjects free of known vascular disease scheduled to undergo a carotid US for clinical risk stratification were invited to undergo CCTA/CACS. Subjects on lipid lowering therapy > 3 months were excluded. All images were assessed by an experienced core laboratory. Carotid intima media thickness ≥75 th percentile for age and sex, CACS > 0 and detection of either carotid or coronary artery plaque were indicators of atherosclerosis. Results: Fifty patients were included. Median age was 53 years; 54% were men. Atherosclerosis was seen in 28%, 78% and 90% of subjects using CACS, CCTA and carotid US, respectively, with all subjects demonstrating one or more markers or findings on at least one method. In the 36 patients with CACS = 0, 69% and 86% had atherosclerosis on CCTA and carotid US, respectively. Maximal concordance (68%, p = 0.021) between carotid US and CCTA was seen when carotid US showed the presence/absence of any plaque with a maximal thickness of ≥ 1.5 mm. Conclusions: In this detailed analysis, all subjects identified to warrant further risk stratification had findings indicating subclinical atherosclerosis on at least one modality. Concordance between the modalities was highly variable, dependent upon the specific definition used. Carotid US and CCTA detection of plaque were more sensitive than CACS > 0. Given strong evidence for low CV risk in patients with CACS = 0, the threshold of subclinical disease at which to treat using Carotid US or CCTA plaque warrants further consideration and caution.