M. A. Tauriainen1, M. Jessen1, J. Pruszynski1 1University Of Texas Southwestern Medical Center,Cardiovascular And Thoracic Surgery,Dallas, TX, USA
Introduction:
Current guidelines recommend surgical replacement of the ascending aorta (AsAo) if the diameter exceeds 5.5 cm. This criterion does not account for differences in age, gender or body size. Accurate assessment of “normal” AsAo size is essential in defining aortic aneurysms, and in identifying patients who warrant surveillance or intervention. Current definitions of normal AsAo aortic dimensions derive from small population samples with limited data on other variables. This study used data collected from a large unselected community population to define normal dimensions of the AsAo and to examine relationships between aortic size and demographic and anthropometric variables.
Methods:
Data were provided from a validated multiethnic, population-based probability sample from an urban community. Adults ≤65 years of age underwent collection of demographic and medical history data. A subset of participants (n=2703) underwent gated aortic magnetic resonance imaging and the diameter of the ascending aorta at the level of the pulmonary artery bifurcation was measured. Age, gender, ethnicity (white, black, Hispanic or other) and multiple indices of body size and composition were collected (including height, weight, waist circumference, hip circumference) or calculated from available data (body mass index [BMI], body surface area [BSA], allometric height [AlloH]). Data from dual-energy x-ray absorptiometry was used to calculate total body fat mass and lean body mass (LBM). Multivariable linear regression analysis was used to determine what factors were associated with aortic diameter. All subsets model selection was used to determine the model of best fit with respect to prediction accuracy, R2, and multicollinearity.
Results:
Model selection indicated that the model of best fit consisted of age, gender, ethnicity, and LBM. Models with other anthropometric measures were found to be of inferior fit. The model was deemed to be statistically significant (p < 0.0001) with a R2 of 36%. Increased age (p < 0.0001) and LBM (p < 0.0001) were found to be associated with increased aortic diameter. Additionally, white patients were found to have increased diameter when compared with black and Hispanic patients (p = 0.0001). The partial effect plots can be seen in the figure.
Conclusion:
The diameter of the ascending aorta appears to increase with age and is larger in certain ethnic groups and in subjects with greater indices of body size. Of the anthropometric variables, a model incorporating LBM appears to have the best correlation with ascending aortic diameter. These factors may need to be considered in defining normal aortic dimensions and may influence recommendations for surgery on the ascending aorta.
