Race-ethnic Variation in Carotid Bifurcation Geometry

Background: Disturbances in local blood flow influenced by arterial geometry contribute to atherogenesis. Carotid bifurcation hemodynamics depend on the relative sizes of the common carotid artery (CCA), internal carotid artery (ICA), and external carotid artery (ECA), which vary considerably among individuals. The prevalence of carotid bifurcation atherosclerosis differs among race-ethnic groups and is generally lower in African Americans despite a more adverse vascular risk factor profile. We here examine whether there are race-ethnic differences in carotid bifurcation anatomy. Methods: The diameters of the CCA, carotid bulb, ICA, and ECA were measured from consecutive cerebral angiograms of African American, white, and Caribbean Hispanic patients. The bulb/CCA, ICA/CCA, ECA/CCA, ECA/ICA, and total cross-sectional outflow/inflow ratio ([ICA² + ECA²]/CCA²) were calculated. Results: The final analysis included 272 bifurcations of which 103 were among white, 87 Hispanic, and 82 African American patients. The mean age of the population was 59.8 ± 15.8 years and 148 (54.4%) were men. African Americans had a lower ICA/CCA ratio (P < .001) and ICA/ECA ratio (P < .0001) and a higher ECA/CCA ratio (P < .0001) in comparison with the other two groups. Conclusion: We found significant differences in the relative sizes of the ICA, ECA, and CCA among race-ethnic groups. African Americans had a proportionally smaller ICA and larger ECA in comparison with whites and Caribbean Hispanics.