Determinants of Echocardiographic Aortic Root Size

BACKGROUND: Previous studies that evaluated the determinants of aortic root size have not yielded uniform results. We examined the relations of age, height, weight, body surface area, sex, and blood pressure to echocardiographically determined aortic root size in a population-based cohort. METHODS AND RESULTS: The study sample consisted of 1849 men and 2152 women in the Framingham Heart Study and Framingham Offspring Study who were free of clinically apparent cardiac disease when echocardiography was performed. Aortic root measurements were made by M-mode echocardiography using a leading-edge-to-leading-edge technique. The relations of age, height, weight, body surface area, and blood pressure variables (contemporary and those obtained 8 years before) to aortic root dimension were examined by use of sex-specific correlations and linear regression analyses. Age, height, weight, and sex emerged as the principal determinants of aortic root dimensions in adults (cumulative R2 = .2085 in men and .2327 in women). The additional effect of contemporary or previous blood pressure measures was small and revealed direct associations of aortic root dimension with mean arterial and diastolic blood pressures and inverse associations with pulse and systolic blood pressures. Previous blood pressure measurements did not contribute significantly to prediction of aortic root size once contemporary blood pressure variable entered the models. Results of regression analyses using a sex-pooled data set showed that on average, the aortic root measurement in women was 2.4 mm smaller than that of men of comparable age, height, and weight. Logistic regression was used to assess the likelihood of aortic root enlargement according to blood pressure levels. After adjustment for age, height, and weight, the odds ratio of aortic dilation for a 1-SD increment in systolic pressure was 0.70 (95% CI, 0.52 to 0.95) in men and 0.79 (95% CI, 0.60 to 1.04) in women; the odds ratio for a 1-SD increment in diastolic pressure was 1.22 (95% CI, 0.91 to 1.63) in men and 1.33 (95% CI, 1.01 to 1.73) in women. CONCLUSIONS: Age, height, weight, and sex emerged as the principal determinants of aortic root dimensions. The additional influences of blood pressure measurements were small; direct associations of aortic root dimensions with mean arterial and diastolic blood pressures and inverse associations with pulse and systolic blood pressures were observed. Additional prospective studies are needed to confirm these observations and to assess the impact of aortic root dimensions on the incidence of hypertension.