Membranous Septum Length Predicts New Conduction Abnormalities in Surgical Aortic Valve Replacement - A novel predictor for PPMI after SAVR

PURPOSE The membranous septum (MS) length measured by cardiac computed tomography (CT) is useful for the prediction of permanent pacemaker implantation (PPMI) and new left bundle branch block (LBBB) after transcatheter aortic valve replacement. However, its predictive value for patients undergoing surgical aortic valve replacement (SAVR) is unknown. Methods: A total of 2531 consecutive patients were registered in the institutional Society of Thoracic Surgeons database between July 2017 and June 2020. Excluding non-SAVR procedures, prior pacemaker/implantable cardioverter defibrillator, prior SAVR, no pre-procedural CT assessment and suboptimal CT imaging. Results: A total of 126 SAVR with pre-procedural CT assessment were analyzed. Bicuspid aortic valve morphology was confirmed on CT in 59.5% of patients. There were three new PPMIs and five new LBBBs observed after SAVR at the time of discharge. In-hospital mortality was 0.8%. Low left ventricular ejection fraction ( 120 g/m 2 , large right coronary artery height and MS length 120 g/m 2 (odds ratio: 9.165; 95% confidence interval: 1.644-51.080; p = 0.011) and MS length < 1.5 mm (odds ratio: 14.449; 95% confidence interval: 1.632-127.954; p = 0.016) were independent predictors for new PPMI/LBBB. Conclusion: Short MS length on preoperative cardiac CT is a powerful and novel predictor for the risk of new PPMI/LBBB after SAVR. Special care should be taken in patients with short MS length to avoid suture-mediated trauma.