Segment-Specific Effects of Cardiovascular Risk Factors on Carotid Artery Intima-Medial Thickness in Women at Midlife

OBJECTIVE: We investigated associations between segment-specific carotid intima-medial thickness (IMT) and cardiovascular risk factors collected before menopause for insight into mechanisms of atherosclerosis development. METHODS AND RESULTS: Participants were 453 healthy women (aged 46 to 58 years) enrolled in a dietary and physical activity randomized clinical trial. Ultrasound scan measures were taken approximately 2.7 years after baseline in the common carotid artery (CCA), bifurcation (bulb), and internal carotid artery (ICA) segments. When scanned, 84% remained premenopausal. In linear regression models adjusted for age, menopausal status, and intervention group, measures independently (P<0.05) and positively associated were as follows: baseline weight (beta=0.007 per 5 kg), systolic blood pressure (SBP; beta=0.008 per 10 mm Hg), and age (beta=0.02 per 5 years) with CCA IMT; smoking (beta=0.08), weight (beta=0.009), and SBP (beta=0.02) with bulb IMT; and apoprotein B (beta=0.01 per 0.1 g/L) with ICA IMT. Differential effects in a repeated measures model with all 3 IMT locations showed these risk factors to have segment-specific positive associations. The effect of weight was strongest in the CCA, smoking and SBP were specific to the bulb, and apoprotein B was strongest in the ICA segment. CONCLUSIONS: Analyses indicate that cardiovascular risk factors may differentially affect IMT in the CCA, bulb, and ICA segments of healthy middle-aged women.