Analysis of atherosclerotic plaque distribution in the carotid artery

BACKGROUND: The present study was designed to investigate the hypothesis that the outer wall at the carotid bifurcation is the most common area of atherosclerotic plaque deposition due to the low shear stress. HYPOTHESIS: We hypothesized that the most common site of arteriosclerosis in carotid arteries is different in the early and late stages. METHODS: This is an observational study of patients with <50% stenosis of the common and internal carotid arteries (ICAs) identified by Duplex ultrasound in our health promotion center. Plaque location was categorized as a quarter of the cross‐section in the distal common carotid artery (CCA) and proximal ICA. Carotid plaque score (CPS) was calculated by the addition of one point for each detected section. The sum of CPSs was calculated for each section. RESULTS: Among 3996 Duplex scans of carotid arteries in 999 patients between June 2020 and October 2020, a total of 569 patients (73.6% male; mean age, 68.4± 9.1 years; 652 CCAs and 567 ICAs) were included. Total CPS was high in the anterior and posterior sections. The distribution in the ICA was: 308 (31.0%) anterior, 90 (9.0%) medial, 373 (37.5%) posterior, and 224 (22.5%) lateral section. The distribution in the CCA was 385 (32.6%) anterior, 103 (8.7%) medial, 528 (44.7%) posterior, and 165 (14.0%) lateral section. The axial distribution of posterior and lateral sections was significantly different according to the directional flow (p < .001). CONCLUSIONS: Anterior and posterior sections of the CCA and ICA were atherosclerotic plaque‐prone sites. This result is different from the tendency of atherogenesis to affect the lateral section having low shear stress at the carotid bifurcation.