Aortic root dilation in bicuspid aortic valve disease: impact on dissection risk and evaluation of guideline-based surgical thresholds - a retrospective cohort study

Abstract

Introduction: To evaluate the impact of aortic root dilation in patients with bicuspid aortic valve (BAV) and to assess guideline thresholds and real-world surgical practices to determine the optimal intervention timing for Stanford type A aortic dissection (AAD).

Methods: From 2008 to 2023, 1582 BAV patients with an aortic diameter ≥40 mm were retrospectively analyzed and categorized into root-dilation (aortic root ≥40 mm) and non-root-dilation groups. AAD risk associated with root dilation was assessed using Firth's penalized Cox regression, inverse probability of treatment weighting-adjusted Cox regression, and Fine-Gray competing risk models. Inflection points were identified via restricted cubic spline (RCS) analysis and validated through receiver operating characteristic and decision curve analysis. Guideline-based thresholds from the 2014 ESC, 2022 ACC/AHA, and 2024 ESC guidelines were evaluated, and real-world surgical practices were analyzed for comparison.

Results: The mean age was 55.8 ± 12.9 years; the median follow-up was 27 months [IQR 19-49]. Root-dilation patients exhibited faster growth of the aortic root (0.86 ± 1.82 vs. 0.77 ± 1.90 mm/year) and ascending aorta (0.93 ± 2.12 vs. 0.79 ± 2.04 mm/year; both P < 0.001). Root dilation conferred over a two-fold increased AAD risk. RCS identified 45 mm (root) and 50 mm (ascending aorta) as key inflection points. The 2024 ESC model had the highest predictive accuracy (AUC = 0.731), with further improvement using revised thresholds (AUC = 0.752). Surgery was performed in 65.3% of patients with root diameters of 45-50 mm, compared to 47.9% with ascending aortic diameters in the same range. Surgery at a 45 mm root diameter was associated with an 88% reduction in AAD risk.

Conclusions: Root dilation in BAV patients is associated with faster aortic growth and a higher AAD risk, supporting earlier surgical intervention. The 2024 ESC guidelines performed best, but further refinement of thresholds may be needed.

Keywords: acute aortic dissection; aortic root dilation; bicuspid aortic valve aortopathy; guideline model.