What is the clinical evidence from this study?

Study design: Cohort. Population: Discrete subaortic stenosis (DSS) (n=508). Intervention: Left ventricular outflow tract gradient (LVOTG) ≥ 35 mmHg vs. LVOTG < 35 mmHg. Primary outcome: Composite of DSS-related adverse events (cardiac death, prosthetic AVR/Bentall, LVOTG ≥ 50 mmHg due to recurrence, surgical reintervention, or moderate/severe AV dysfunction) (HR 6.1, 95% CI 3.2-11.6, p=<0.001).

What question did this study set out to answer?

The study aims to determine prognostic factors for discrete subaortic stenosis and reevaluate surgical intervention thresholds.

June 12, 2026Open Access

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

Q: What are the key findings of this study?

A preoperative left ventricular outflow tract gradient ≥ 35 mmHg was independently associated with an increased risk of adverse DSS-related events (HR 6.1) compared to lower gradients.

Q: What question did this study set out to answer?

The study aims to determine prognostic factors for discrete subaortic stenosis and reevaluate surgical intervention thresholds.

YJYu-Tong JiangChinese Academy of Medical Sciences & Peking Union Medical College TZTing-Ting ZhangChinese Academy of Medical Sciences & Peking Union Medical College L(Li Zhang (8200)Chinese Academy of Medical Sciences & Peking Union Medical College

Key Result

A preoperative left ventricular outflow tract gradient ≥ 35 mmHg was independently associated with an increased risk of adverse DSS-related events (HR 6.1) compared to lower gradients.

Key Points

The study aims to determine prognostic factors for discrete subaortic stenosis and reevaluate surgical intervention thresholds.
Retrospective analysis of 508 patients with discrete subaortic stenosis who underwent surgery
Follow-up duration of 3.5 years
Multivariable Cox regression and ROC analyses were utilized to identify predictors.
19.2% of pediatric patients experienced the primary endpoint
An LVOTG ≥ 35 mmHg associated with HR = 6.1 (95% CI: 3.2–11.6, P < 0.001) for adverse outcomes
An LVOTG threshold of ≥ 35 mmHg may be a better risk alert than ≥ 50 mmHg.

Study Design

Type

Cohort (n=508)

Multicenter

Structured PICO

Does an LVOTG threshold of ≥35 mmHg provide better prognostic risk-alert for surgical intervention compared to the current ≥50 mmHg standard in patients with discrete subaortic stenosis?

Population

508 patients (including 375 pediatric patients) with discrete subaortic stenosis who underwent surgical intervention, followed for a mean of 3.5 years.

Exposure

Surgical intervention for DSS evaluated against preoperative left ventricular outflow tract gradient (LVOTG) thresholds (specifically assessing ≥35 mmHg).

Comparator

Current standard surgical threshold of LVOTG ≥50 mmHg, and lower threshold of LVOTG <35 mmHg.

Outcome

Composite of DSS-related adverse events (cardiac death, prosthetic aortic valve replacement or Bentall procedure, LVOTG ≥50 mmHg due to membrane recurrence, surgical reintervention for DSS, or AV dysfunction defined as moderate or severe aortic stenosis or aortic regurgitation).composite

An LVOTG threshold of ≥35 mmHg provides comparable prognostic accuracy to the current ≥50 mmHg standard for surgical intervention in discrete subaortic stenosis, suggesting earlier surgery may improve long-term outcomes.

Main Result

Hazard Ratio: 6.1 (95% CI 3.2–11.6)

p-value: p=<0.001

Limitations

Retrospective design inherently carries risks of selection bias and unmeasured confounding
Single high-volume tertiary cardiac center may limit the generalizability of findings
Potential inter-observer variability in LVOT gradient assessment from archived digital images
Follow-up period may not fully capture long-term complications such as progressive AV dysfunction or late reoperation
External validation in a prospective cohort is necessary before incorporation into clinical guidelines

Abstract

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.

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