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

Transcatheter aortic valve replacement (TAVR) is an established therapy for severe aortic stenosis, although conduction disturbances, especially atrioventricular block and new-onset left bundle branch block (LBBB) remain associated with adverse outcomes. Short membranous septal length (MSL) has been linked to post-TAVR conduction abnormalities, but its prognostic significance is unclear. We retrospectively analyzed 258 patients who underwent transfemoral TAVR. MSL was measured on contrast-enhanced CT, and left ventricular ejection fraction (LVEF) was assessed at baseline, 1 week, and 1 year. The primary endpoint was all-cause mortality; secondary was a composite of mortality or heart failure hospitalization. Patients were classified by MSL ≤ 6 mm or > 6 mm. The short MSL group had higher rates of new-onset LBBB (p = 0.047), mortality (p = 0.046), and the composite endpoint (p = 0.039). MSL ≤ 6 mm independently predicted mortality (HR 3.66, 95% CI 1.52-16.2, p = 0.0012) and the composite outcome (HR 2.56, 95% CI 1.32-6.69, p = 0.0025). LVEF recovery at 1 year was significantly impaired (p = 0.035), and these findings persisted after excluding patients with LBBB or pacemaker implantation. Incorporating MSL ≤ 6 mm into a model with established risk factors improved discrimination for mortality (AUC 0.72 vs 0.67, p = 0.042; cfNRI 0.33). Short MSL was associated with impaired LVEF recovery and adverse outcomes after TAVR. MSL may serve as a simple CT-based marker for preprocedural risk stratification.