Abstract P135: Aortic Areas at Multiple Locations are Independent Correlates of Multiple Subclinical Cardiovascular Disease Measures
Authors: Kuipers Allison L , Carr J J , Terry James G , Nair Sangeeta , Barinas-Mitchell Emma , Wheeler Victor W , Miljkovic Iva 
Published: March 2020

To handle the force from high blood pressure, arteries throughout the vasculature undergo outward remodeling, which can be assessed through measurement of arterial dimension. While the proximal aortic size is indicative of aneurysm risk, other regions of the aorta, such as the descending or abdominal aorta, may be more reflective of general aortic remodeling. However, there have been no studies using multiple measures of aortic size and their association with established subclinical cardiovascular disease (CVD) markers.

Therefore, we aimed to measure aortic area at three locations along its length: the ascending thoracic aorta (ASC), the descending thoracic aorta (DSC), and the abdominal aorta (ABD) and to test for associations with subclinical CVD measured via carotid ultrasound, arterial calcification, and brachial ankle pulse-wave velocity (PWV). Preliminary analyses were conducted on data from 279 African ancestry men from Tobago (mean age 64 years, range 53-89 years). Aortic areas (cm
2
) were measured from computed tomography (CT) scans of the chest (ASC and DSC; measured on the same transverse plane at the location of the pulmonary artery) and the abdomen (ABD; measured at the midpoint of L3). The mean of 3 contiguous CT slices was used for each aortic area measure. Each area was individually tested for association with age, body size, blood pressures, and lifestyle factors (including smoking, physical activity, and alcohol), and significant covariates were included in the fully adjusted models.

All aortic areas were correlated with each other (r=0.40-0.66, all P<0.0001). Greater age and weight were predictive of greater aortic area at all three locations (P<0.0001 for all). ASC and DSC were also associated with higher blood pressures (P<0.01, for all). No aortic measure was significantly associated with lifestyle factors. After full adjustment, ASC, DSC, and ABD areas were associated with carotid interadventitial diameter (r=0.34, 0.22, 0.20, respectively; all P<0.001). ASC was also positively associated with carotid intima-media thickness (P<0.01). While ABD was associated with abdominal aortic calcification (P<0.001), no area was associated with coronary artery calcification. Lastly, both ABD and DSC were correlated with greater PWV (r=0.24 and 0.16, P<0.005 for both), with DSC being significantly associated with PWV independent of ABD.

This is the first study to test the association of aortic size measured at multiple points with established measures of subclinical CVD. While ASC and DSC were associated with age, blood pressures, and carotid outward remodeling, ABD was more strongly correlated with aging-related vascular changes. Additionally, DSC, which can be measured from clinical chest CTs, may be a novel indicator of arterial stiffness independent of age and blood pressures. Longitudinal studies are needed to determine the predictive value of aortic area measurement.