Abdominal aortic diameter and vascular atherosclerosis: the Multi-Ethnic Study of Atherosclerosis

To gain insight into early mechanisms of aortic widening, we examined associations between the diameter of the abdominal aorta (AD) and cardiovascular disease (CVD) risk factors and biomarkers, as well as measures of subclinical atherosclerosis, in a multi-ethnic population.

Cross-sectional cohort.

A total of 1926 participants (mean age 62, 50% women) underwent chest and abdomen scanning by computed tomography, ultrasound of the carotid arteries, and CVD risk factor assessment. AD was measured 5 cm above and at the bifurcation.

In a model containing traditional CVD risk factors, biomarkers and ethnicity, only age (standardized β = 0.97), male sex (β = 1.88), body surface area (standardized β = 0.92), current smoking (β = 0.42), D-dimer levels (β = 0.19) and hypertension (β = 0.53) were independently and significantly associated with increasing AD (in mm) at the bifurcation; use of cholesterol-lowering medications predicted smaller AD (β = -0.70) (P < 0.01 for all). These findings were similar for AD 5 cm above the bifurcation with one exception: compared to Caucasian-Americans, Americans of Chinese, African and Hispanic descent had significantly smaller AD 5 cm above the bifurcation (β's = -0.59, -0.49, and -0.52, respectively, all P < 0.01), whereas AD at the bifurcation did not differ by ethnicity. Physical activity, alcohol consumption, diabetes and levels of IL-6, CRP and homocysteine were not independently associated with AD. Higher aortic and coronary artery calcium burden, but not common carotid artery intima-media thickness, were independently, but modestly (β = 0.11 to 0.19), associated with larger AD.

Incremental widening of the aortic diameter shared some, but not all, risk factors for occlusive vascular disease.