1356909 - Altered Aortic Arch Morphology Assessed using 3D-MRA is related to more Advanced Aortopathy and Cardiometabolic Risk Profile in Turner Syndrome

Turner syndrome (TS) is associated to early vascular aging with higher risk of aortic aneurysm and related complications. Guidelines recommend screening using an indexed diameter threshold ≥20 mm/m² for aortic dilatation and ≥25 mm/m² for prophylactic surgery. Determinants of aortic dilatation remain poorly defined in TS. Aortic arch unfolding and increased stiffness have been associated with early vascular aging and hypertension in the general population. Our objectives were to evaluate in a large TS population: 1. thoracic aorta morphology and its relationship with valvular status and aortic dimensions; 2. determinants of regional aortic growth; 3. aortic outcome in TS.

Methods:

From 2012 to 2022, 111 patients with TS who underwent at least one aortic MRI were included. 3D imaging of the aorta was obtained from an isotropic ECG-gated and respiratory navigated contrast-enhanced SSFP sequence. Aortic maximal diameter and cross-sectional area were measured at reference anatomical landmarks using MPR at baseline in all patients and during follow-up (55 ±20 months) in a subgroup of 40 patients. Cross-sectional SSFP cine imaging was performed to study valvular dynamics. Regional indexed aortic surface growth rates were calculated. Patients were classified into four groups: tricuspid-aortic-valve-roman-arch (TAV-R), tricuspid-aortic-valve-non-roman-arch (TAV-NR), bicuspid-aortic-valve-roman-arch (BAV-R) and bicuspid-aortic-valve-non-roman-arch (BAV-NR). ANOVA was used to study differences in means and growth rates across groups.

Results:

Among 111 patients with TS, 26% had bicuspid aortic valve (BAV), 26% had non-roman aortic morphology (krenel or gothic) and 43% had at least one dilated aortic segment (≥20 mm/m²), mainly the sinuses of Valsalva (43%) and mid-ascending aorta (16%). Non-roman aortic arch was associated with increased age, a more severe cardiometabolic risk profile and increased prevalence of BAV and aortic regurgitation. The prevalence of aortic root dilatation increased from 31% in the TAV-R group, 40% in the TAV-NR group, 60% in the BAV-R group to 86% in the BAV-NR group. The proportion of patients with moderate and severe ascending aorta dilatation was significantly increased in BAV-NR patients. BAV (p=0.005) and hypothyroidism (p=0.003) were independent determinants of ascending aorta dilatation rate. During follow-up, the two patients who underwent aortic intervention belonged to the BAV-NR group.

Conclusion:

The classification of TS patients according to aortic valve status and aortic arch morphology allows to identify a spectrum of aortic involvement related with increasing morphological alteration. The BAV-NR group identifies a phenogroup associated with a higher degree of dilatation and elongation of the proximal aorta and higher cardiometabolic risk profile. Increased growth rate in patients with TS is mainly associated with BAV. Whether such hierarchical approach may predict aortic events in patients with TS will require larger longitudinal studies.