Membranous septum morphology predicting the risk of conduction abnormalities after transcatheter aortic valve implantation.

Background There is limited data on the association of membranous septum (MS) morphology and transcatheter heart valve (THV) implantation depth, and the development of new conduction abnormalities after transcatheter aortic valve replacement (TAVI). Aims To describe the morphology of the MS and predict the risk of new CA after TAVI based on the MS morphology and THV implantation depth. Methods Based on pre-procedural CT-scans the MS depth was measured for every 25% of the entire MS width in 272 TAVI-patients without pre-procedural bundle branch block (BBB) or pacemaker. Post-procedural CT-scans for THV implantation depth assessment were available in 130 of these patients. Results The MS depth was a median of 2.5mm (IQR 1.4 - 3.8) deeper at the posterior edge when compared to the anterior edge of the MS. New CA developed in 7.1% of patients in whom the THV did not cross the lower MS border at its anterior edge (3.6% with new BBB and high degree CA, respectively); in 18.8% of patients (15.6% with new BBB and 3.1% with new high-degree CA) where the THV overlapped the lower MS border by l2.5mm and in 47.1% of patients (24.3% with new BBB and 22.9% with new high-degree CA) with THV overlap of the lower MS border by ≥2.5mm. Conclusions The difference of the MS depth and THV implantation depth measured at the anterior edge of the MS predicted new CA after TAVI.