Impact of short membranous septal length on overall survival after transcatheter aortic valve replacement

Abstract Background Transcatheter aortic valve replacement (TAVR) is an effective treatment for patients with severe aortic stenosis (AS) who are at high surgical risk. Among anatomical factors influencing TAVR outcomes, membranous septal length (MSL) has recently gained attention. A short MSL is a known risk factor for new-onset left bundle branch block (LBBB) after TAVR, a conduction abnormality associated with increased mortality and heart failure (HF) hospitalization in patients with cardiovascular disease. However, the direct prognostic significance of MSL on post-TAVR outcomes remains uncertain. As MSL measurement is routinely performed via preoperative computed tomography (CT), its potential utility as a prognostic marker could enhance risk stratification and post-procedural management strategies. Purpose This study aimed to assess the impact of MSL on the risk of all-cause mortality and HF hospitalization in patients with severe AS undergoing TAVR. Methods This retrospective cohort study included patients with severe AS who underwent TAVR at our hospital between January 2021 and December 2023. The primary endpoint was all-cause mortality, and the secondary endpoint was a composite of all-cause mortality or HF hospitalization. Results 258 Patients were included and categorized into two groups: MSL ≤6mm (n=211) and MSL 6mm (n=47). The median follow-up duration was 385 days. Newly developed LBBB was significantly more frequent in the MSL ≤6mm group (Pearson’s chi-square test, p=0.047). Patients with MSL ≤6mm had significantly higher all-cause mortality (log-rank test, p=0.046) and all-cause mortality or HF hospitalization (log-rank test, p=0.036). Cox proportional hazards analysis identified MSL ≤6mm as an independent predictor of all-cause mortality (HR 3.66, 95% CI 1.52–16.23, p=0.0012) and all-cause mortality or HF hospitalization (HR 2.56, 95% CI 1.32–6.69, p=0.0025), even after adjusting for age, sex, and NT-proBNP. ROC analysis demonstrated that incorporating MSL into a predictive model with established mortality risk factors for TAVR (left ventricular ejection fraction 40%, eGFR 45 mL/min, and NT-proBNP 2000 pg/mL) significantly improved discriminative power for post-TAVR mortality (AUC 0.693, 95% CI 0.586–0.783) compared to a model without MSL (AUC 0.643, 95% CI 0.525–0.745; ΔAUC = 0.050, p=0.034). Conclusion MSL ≤6mm is associated with an increased incidence of new-onset LBBB after TAVR and an independent predictor of post-TAVR mortality and HF hospitalization. Given its routine assessment via preoperative CT, MSL could serve as a practical prognostic marker to enhance risk stratification and optimize post-TAVR management.Kaplan-Meier Curve