Segment-Specific Analysis of Carotid Intima-Media Thickness and Its Association with Cardiovascular Risk Factors in a Large Healthy Cohort

Background: Carotid intima-media thickness (IMT) is a noninvasive surrogate marker of subclinical atherosclerosis and cardiovascular disease risk. This study explored IMT distribution across three carotid artery segments in a large cohort of healthy individuals and identified the key factors associated with increased IMT. Methods: This study utilized data from the Kangbuk Samsung Health Study, a cohort of South Korean adults aged ≥ 18 years who underwent comprehensive annual or biennial health examinations. The analysis included 86,351 healthy individuals, excluding those with known carotid disease. IMT was measured using high-resolution B-mode ultrasonography across the three segments: common carotid artery (CCA), carotid bulb, and internal carotid artery (ICA). An increased IMT was defined as a measurement of ≥1.5 mm in any segment. Multivariable linear regression analyses were conducted to identify independent predictors of increased IMT. Results: The study population had a mean age of 46.7 years and was predominantly male (69.7%). The prevalence of thickened IMT was the highest in the carotid bulb, followed by the ICA and CCA. IMT increased progressively with age and was higher in males across all segments, with the disparity becoming more pronounced after 65 years of age. The carotid bulb displayed the largest absolute IMT values, whereas the ICA exhibited a sharper age-related increment. Increased CCA IMT was strongly linked to hypertension (beta, 0.11; p < 0.001) and diabetes mellitus (beta, 0.12; p < 0.001). Both CCA and ICA IMT showed a weak but significant association with dyslipidemia (beta, 0.03; p < 0.001). Conclusions: The IMT distribution and its determinants vary across carotid segments. CCA is a robust marker of systemic vascular health, whereas the carotid bulb is the most sensitive marker for detecting early atherosclerotic changes. This study provides novel insights into segment-specific IMT patterns and their association with cardiovascular risk factors in a large, healthy Asian population.