Abstract
Background: Internal carotid artery (ICA) angle of origin is considered a contributor to atherogenesis because of its influence on hemodynamics. It is controversial if ICA angle variations are causal or consequential to carotid atherosclerosis or vascular risk factors. We aim to determine whether vascular risk factors underly ICA angle interindividual variations. Methods: The study included 1,111 stroke-free participants of the population-based Northern Manhattan Study (NOMAS) who underwent ICA angle estimation using B-mode carotid ultrasound (mean age 68.7±8.9 years; 41% were men, 60% Hispanic, 21% Black, and 18% White). Multivariable linear regression models were fit to assess the relationship of ICA angle to vascular risk factors. Results: ICA angle was significantly wider on the left compared to the right (26.6 ±15.5 degrees versus 18.6 ±12.9 degrees; p<0.001). In multivariate analyses, left ICA angle was correlated with age (B=0.07; p=0.03), female sex (B=0.09; p=0.004), Black race (B=0.11; p=0.02), and diastolic blood pressure (B=0.16; p<0.001), whereas right ICA angle was positively correlated with body mass index (B=0.07; p=0.04) and physical inactivity (B=0.08; p=0.02), and inversely correlated with low-density lipoprotein level (B=-0.1; p=0.004). Overall, these factors explained less than 5% of ICA angle variance (R 2 =0.0399 on the left; R 2 =0.0197 on the right). Conclusion: ICA angle variations are poorly explained by vascular risk factors at the population level. Our results suggest ICA angle is an independent feature that may predispose to atherogenesis.
