Dilatation of the Ascending Aorta in Turner Syndrome: Influence of Bicuspid Aortic Valve Morphology and Body Composition

Abstract

Background: Aortic dilatation and bicuspid aortic valve (BAV) are frequent in Turner syndrome (TS). Due to short stature, aortic size index (ASI)-ascending aortic diameter (AD)/body surface area (BSA)-is used to identify aortic dilatation in TS patients. We sought to: 1) describe echocardiographic findings in the largest cohort of Australian women with TS; 2) assess if ASI progresses differently with age in TS BAV compared to non-syndromic BAV; and 3) determine whether adjustment of AD for body composition may be superior to BSA indexation.

Methods: Transthoracic echocardiography (TTE) data were retrospectively collected on 125 women with TS. Body composition was quantified by dual energy X-ray absorptiometry (DXA) in 60 women within 6 months of baseline TTE. Age-matched females with non-syndromic BAV (n=170) were used as controls for TS patients with BAV.

Results: Mean age of TS women was 28±16 years, and mean height and BSA were 141.6±21.7 cm and 1.4±0.4 m², respectively. Mean AD was 2.5±0.8 cm, and ASI 2.0±0.6 cm/m². Aortic dilatation (ASI >2.0 cm/m²) was present in 42 (34%) patients. Turner syndrome women with BAV (n=34; 27%) had a larger ASI than those with tri-leaflet AV (2.2±0.4 cm/m² vs. 1.7±0.3 cm/m², p<0.001). In the pooled BAV cohort, TS patients had a higher baseline ASI (2.2±0.4 cm/m² vs. 2.1±0.3 cm/m², p=0.02) and greater increase in ASI with age (0.21 mm/m²/year vs. 0.10 mm/m²/year, p=0.01) compared to non-syndromic BAV patients. DXA fat-free mass (r=0.33, p=0.01) and lean mass (r=0.32, p=0.02) correlated with AD, as did BSA (r=0.62, p<0.001).

Conclusion: Turner syndrome women with BAV have a greater degree of baseline aortic dilatation and a twofold faster increase in aortic dimension with age when compared to matched women with non-syndromic BAV. Several DXA-derived body composition parameters correlate with aortic size in TS, however BSA appears to be the most robust method of indexation.

Keywords: Aortic dilatation; Bicuspid aortic valve; Body composition; Echocardiography; Turner Syndrome.