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

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.