Abstract P249: Determinants of Descending Aortic Dimensions in a Multi-Ethnic Population: The Dallas Heart Study

Introduction: Accurate description of normal aortic size is fundamental to our ability to define aortic aneurysms. However, current definitions of normal aortic dimensions are based on small population samples with limited data on other variables. This study used data from a large unselected community population to define normal aortic dimensions and to examine relationships between aortic size and demographic and anthropometric variables. Methods: Data came from a validated multiethnic urban population sample. Adults (age 18 – 65) underwent collection of demographic and medical history data. A subset of participants (n=2643) underwent gated aortic MRI to measure descending aortic diameter at the level of the pulmonary artery bifurcation. Age, gender, ethnicity (white, black, Hispanic or other) and multiple indices of body size and composition were collected or calculated from available data (body mass index [BMI], body surface area [BSA]). Dual-energy x-ray absorptiometry was used to calculate total body fat mass and lean body mass. A univariate analysis was performed relating descending aortic diameter to each variable. A stepwise variable selection using a p-value criteria of 0.15 for entry and removal was used to identify variables independently associated with aortic size. Results: By univariate analysis, increased aortic size was associated with increased age, male gender, black ethnicity, and greater height, weight, waist and hip circumference, BMI, BSA , total body fat mass and total body lean mass. By multivariable analysis, age, lean body mass, ethnicity, gender, waist circumference, and hip circumference emerged as significant determinants of descending aortic diameter (see Table). Conclusions: The diameter of the descending aorta appears to increase with age and is larger in certain ethnic groups and in subjects with greater indices of body size. Definitions of normal values for descending aortic dimensions may need to consider these factors.