Computed tomography (CT) assessment of the membranous septal anatomy prior to transcatheter aortic valve replacement (TAVR) with the balloon-expandable SAPIEN 3 valve

Objectives: The lower limit of the membranous septum (MS) is considered an anatomic landmark for the emergence of the Bundle of His into the left ventricle. Computed tomography (CT) assessment of MS anatomy may provide useful information about the risk of conduction abnormalities following transcatheter aortic valve replacement (TAVR). Methods and results: The study included 102 consecutive patients undergoing TAVR with the Edwards Sapien 3 (S3) valve. Using pre-TAVR CT and post-procedure angiography we evaluated for the presence of calcium in the left ventricular outflow tract (LVOT), calcium depth (CD), implantation depth (ID) and MS length. The MS length minus the prosthesis ID was calculated (Delta MSID). Outcomes included new left bundle branch block (LBBB) or permanent pacemaker (PPM) within 30 days. Seventeen patients (17%) received a PPM and 28 (27%) developed new LBBB following TAVR. Mean (± SD) MS length and delta MSID were 7.5 mm (2) and 0.9 mm (4.5), respectively. Twenty-one patients (20%) had calcium in the device landing zone and the mean (SD) CD was 6.8 mm (± 4). Calcium in the device landing zone (37% versus 16%, p = 0.02) and implantation depth (6 mm (4–8) versus 4 mm (4–5), p = 0.02) predicted new conduction abnormalities after TAVR. Conclusions: The presence of calcium in the device landing zone is associated with increased risk of conduction abnormalities after TAVR with S3. In such cases, a more aortic deployment of the prosthesis may be warranted.