Abstract 2539: Relationship of Aortic Wall Thickness and Distensibility with Subclinical Measures of Cardiovascular Disease: The Multi-Ethnic Study of Atherosclerosis

Abstract

Background: While increased carotid intima-media thickness (IMT) is considered an independent risk factor for cardiovascular disease (CVD), little is known about the relationship of aortic thickness (AWT) and aortic distensibility (AD) with CVD risk factors. We studied the association of these aortic parameters with other measures of subclinical CVD. Methods: The Multi-Ethnic Study of Atherosclerosis (MESA) includes 6,814 participants, aged 45– 85 years; white, African-American, Hispanic, and Chinese. AD and AWT were measured by MRI. Average and maximum AWT of the proximal descending thoracic aorta were used as two measures of AWT. AD was calculated as the difference in aortic cross-sectional area indexed by diastolic cross-sectional area and average pulse pressure. IMT of the common and internal carotid arteries were determined by high-resolution B-mode ultrasonography and LV mass was determined by MRI. Phantom-adjusted Agatston calcium score from CT images was used to define coronary artery calcification (CAC). Results: In univariable analyses, higher carotid IMT, ankle-brachial index (ABI) <0.9, CAC score, LV mass, and presence of coronary calcium were associated with lower AD and higher AWT (table ). However, in multivariable analyses, the only measures of subclinical CVD that had significant associations with both AD and AWT were LV mass and carotid IMT, while ABI was associated with only AWT. After adding age to the models, CAC score was no longer associated with either AD or AWT. The relationship between CAC score and AD varied by ethnicity; higher CAC score was associated with higher AD only in African Americans. Conclusions: AD and AWT are related to carotid IMT and LV mass, even after controlling for traditional risk factors. The associations of AD and AWT with CAC appears to be mainly due to their relationship with conventional risk factors, particularly age. Overall, AWT and AD may have closer relationship with LV mass than with subclinical atherosclerosis.