Longitudinal Echocardiographic Surveillance of Aortic Dilation in a Phenotype‐Enriched Turner Syndrome Cohort

Turner syndrome (TS) is associated with thoracic aortopathy and increased risk for aortic dissection, yet the natural history of aortic dilation is not well understood. We performed a retrospective longitudinal study of individuals with TS who participated in the TS Society of the United States Healthy Heart Project between 2003 and 2023. Participants were selected in descending rank order of aortic size index (ASI, > 18) or TS-specific Z-score (< 18) to generate a cohort intentionally enriched for the largest unoperated aortic diameters. Serial echocardiograms were re-measured using standardized techniques. Patient-specific growth rates were estimated using a pooled mixed-effects best-model framework and compared with the entire HHP longitudinal dataset to evaluate trajectories across risk strata. The primary endpoint was a composite of all-cause death, aortic surgery, or aortic dissection. Twenty-nine individuals (20 adults, 9 pediatric) were followed for a median of 13 years. Longitudinal aortic growth was generally slow (≤ 0.018 cm/year), with three rapid and seven mild progressors. No aortic dissections were observed. Clinical events were driven by elective aortic surgery and death. Height-indexed aortic diameter (aortic height index, AHI) demonstrated the strongest association with the composite endpoint, outperforming ASI and TS-specific Z-scores. In a TS cohort enriched for the largest unoperated aortas, baseline aortic size and clinical risk factors rather than growth rate primarily determined clinical outcomes. These findings support an integrated framework for aortic risk assessment in TS.