Endocrine Abstracts

Background: Aortic sized index (ASI) defined as aortic dimensions/body surface area (BSA), has been proposed as a method of identifying aortic dilatation in Turner syndrome. A recent paper reported centile charts of aortic dimensions across for BSA using echocardiogram in 451 children and adults with TS allowing for calculation of Z scores.¹

Methods: We report Z scores for aortic root adjusted for BSA from clinical echocardiogram (ECHO) from a group of children and adults with TS. Results reported as median (range).

Results: Sixty-four individuals with TS (27, 45X) median age of 17.8 years (1.1, 58.2). 7/64 had a history of coarctation of aorta. Median ASI root for the whole cohort was 1.7 cm/m² (1.0, 3.7). Median root Z score for the whole cohort was −0.21 (−3.81, 3.96). 4/64 (6.3%) had ASI >2.5 cm/m², currently defined as significant aortic dilatation and very high risk of aortic dissection. Median ASI of these four individuals was 3.55 cm/m² (2.7, 3.6) whereas median aortic root Z score was +0.27 (−1.77, +3.44) with median age at ECHO 1.75 years (1.1, 36.8). ¾ of these individuals had root Z score within ±2 S.D., all of whom were young growing children. Linear regression showed a significant association between age and ASI (β co-efficient=−0.37, P=0.002, 95% CI −0.03 to −0.006). This relationship was significant in individuals ≤18 years (β co-efficient=−0.86, P≤0.0001, 95% CI −0.14 to −0.09) but not in those >18 years (β co-efficient=−0.08, P=0.67, 95% CI −0.02 to +0.01).

Conclusion: Using current cut-offs of ASI >2.5 cm/m², 75% of TS individuals especially younger growing children were misclassified as having aortic dilatation when aortic dimensions were expressed as Z scores for BSA. The negative association between age and ASI especially in growing children suggests that ASI is not appropriate as a method of identifying aortic dilatation in young girls with TS. Recommendations for consideration of cardiothoracic surgery in children with TS and ASI >2.5 cm/m² may be unnecessary.²

References: 1. Quezada E et al. Am J Med Genet A, 2015.

2. Turtle E et al. Arch Dis Child 100 662–666, 2015.