Sex-Specific Association of Age with Carotid Artery Distensibility: Multi-Ethnic Study of Atherosclerosis

BACKGROUND: Older women have a higher prevalence of systolic hypertension than do men; however, whether or not this relates to arterial properties, such as distensibility coefficient (DC), is not known. We examined whether the association of carotid artery DC with age differed by sex in the Multi-Ethnic Study of Atherosclerosis (MESA). METHODS: B-mode ultrasound-measured carotid diameters and brachial pressures were obtained from 6359 participants (53% female, 38% white, 12% Chinese, 27% black, 22% Hispanic, aged 45-85 years) of the MESA baseline examination. The within-individual slopes of 2log(diameter) vs. blood pressure fit using mixed models (MM) are interpreted as the DC, and interaction terms are interpreted as differences in DC. The MM calculation allows for correction of the confounding caused by the association of age, sex, and race with blood pressure, the denominator in the calculation of DC. RESULTS: DC was associated with age, sex, and race (all p<0.001). Women had a greater age-related lowering of DC compared to men (2.52×10(-5) vs. 2.16×10(-5)/mm Hg lower DC per year of age, p=0.006). Mean diameter of carotid arteries was greater with age (p<0.001); this association also was significantly stronger in women compared to men (0.24% vs. 0.14% larger mean carotid diameter per year of age, p<0.001). CONCLUSIONS: Greater stiffening and enlargement of arteries are seen in older women compared to older men. This implies that the afterload on the heart of older women is likely to be greater than that among older men.