Individual, expected diameters of the ascending aorta and prevalence of dilations in a study-population aged...

To determine individual, expected normal diameters of the ascending aorta (AAo) and prevalence of dilations based upon an absolute cut-off point (≥ 40 mm) and individual cut-off point (≥ 25% than expected normal). Non-contrast computed tomography (CT) scans were obtained in 14,993 individuals (95.0% male, mean age 67.8 ± 3.8). A sub-group (n = 291) had AAo diameter measured by transthoracic echocardiography. A prediction formula for AAo diameters was created from multivariate linear regression analysis based upon gender, age, and body surface area. An index was made by dividing observed diameters with predicted diameters. A size-index ≥ 1.25 was defined as dilated. Prevalence of AAo dilations among males and females using 40 mm as cut-off point were 10.6% and 2.1% (p < 0.001), respectively, while 3.3% and 2.6% (p = 0.305) using the size-index ≥ 1.25, respectively. Proportion of agreement between cases of AAo dilations from the size-index and 40 mm was 93.0%. Using the size-index as 'golden standard' for dilation, the sensitivity and specificity using 40 mm as cut-off point for males were 100.0% and 92.4%, respectively, while 75.0% and 99.9%, respectively, for females. For males and females, the positive predicted values were 31.3% and 93.8%, respectively; the negative predicted values were 100.0% and 99.3%, respectively. An absolute echocardiographic size-criterion of 40 mm entails a significant number of females with missed AAo dilation, and a large number of males are mistaken to have dilated AAo. Thus, AAo diameters should be evaluated in relation to gender, age and BSA. This study provides a formula for potential clinical implementation.