Discrete subaortic stenosis: prognostic value of the left ventricular outflow tract gradient and implications for earlier surgical intervention.

Abstract

Background: The optimal timing of surgery for discrete subaortic stenosis (DSS) is controversial due to limited evidence from large-scale trials. This study aimed to identify prognostic factors and reassess current surgical thresholds.

Methods: A total of 508 patients with DSS, including 375 pediatric patients, who underwent surgery at a single tertiary center between May 2018 and March 2025 were retrospectively analyzed. The primary endpoint was a composite of DSS-related adverse events, and the secondary endpoint was aortic valve (AV) dysfunction. Multivariable Cox regression and receiver operating characteristic (ROC) analyses were used to identify predictors.

Results: Over a mean follow-up period of 3.5 years, 19.2% of pediatric patients experienced the primary endpoint and 13.3% developed AV dysfunction. Left ventricular outflow tract gradients (LVOTG) ≥ 20 mmHg [hazards ratio (HR) = 4.0, 95% confidence interval (CI): 2.0-7.8, P < 0.001], ≥ 35 mmHg (HR = 6.1, 95% CI: 3.2-11.6, P < 0.001), and ≥ 50 mmHg (HR = 3.5, 95% CI: 1.9-6.4, P < 0.001) were all independently associated with adverse outcomes. Of note, an LVOTG ≥ 35 mmHg provided comparable prognostic accuracy to ≥ 50 mmHg (P = 0.180) but superior risk discrimination compared with 20 mmHg ≤ LVOTG < 35 mmHg (P < 0.001). Additional independent predictors included older age at surgery, moderate or greater aortic regurgitation.

Conclusions: An LVOTG threshold of ≥ 35 mmHg may offer a more appropriate risk-alert threshold than the current ≥ 50 mmHg standard. Earlier surgical intervention, particularly in patients with AV involvement, may help improve long-term outcomes in DSS.