Anatomical characteristics of the membranous septum are predictive of pacemaker requirement in patients undergoing transcatheter aortic valve replacement.

PURPOSE: We aimed to study the characteristics of the membranous septum (MS) and its relationship with the aortic valve (AoV) and aortic annulus (AA) in patients who required PPM post-TAVR.

METHODS

We performed a retrospective case-control study of 144 patients undergoing TAVR from 2016 to 2018. Thirty-four patients, requiring PPM implantation, were compared with 34 matched controls who did not require pacing. The total MS length, supra-annular MS (SA-MS) length, infra-annular MS (IA-MS) length, angle between the plane of the AA and MS (AA-MS), and degree of AoV calcifications (AVC) were obtained from preoperative CT. AoV prosthesis implantation depth was obtained from intra-operative fluoroscopy.

RESULTS

There were no significant differences in valve type (self-expandable: 23 cases vs 25 controls, and balloon-expandable: 11 vs 9, p = 0.79), degree of AVC (0.65 cm3 vs 0.82 cm3, p = 0.62), or implantation depth (7.76 mm vs 7.28 mm, p = 0.83). Compared to controls, there was no difference in total MS length (6.68 mm vs 6.06 mm, p = 0.97), but the IA-MS was significantly shorter (3.64 mm vs 4.56 mm, p = 0.02) and the SA-MS was significantly longer (2.73 mm vs 1.67 mm, p = 0.02) in patients requiring PPM. Patients requiring PPM also had a larger AA-MS angle (103.5° vs 96.7°, p = 0.01).

CONCLUSION

The position of the MS with respect to the AA and MS distance below the annular plane were more closely associated with post-TAVR conduction abnormalities requiring PPM than the absolute length of the MS. Patients undergoing TAVR with such anatomy have a higher risk of requiring PPM and should be monitored for developing these complications.