Impact of tapered-shape left ventricular outflow tract on pacemaker rate after transcatheter aortic valve replacement

Mechanical compression of left ventricular outflow tract (LVOT) was reported to be a leading cause of conduction impairment requiring permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement (TAVR). However, the association between tapered-shape LVOT and PPI after TAVR has not been elucidated. Of 272 consecutive patients treated with SAPIEN 3 in our institute, we retrospectively analyzed the clinical data of 256 patients without previous PPI or bicuspid valve. In-hospital PPI was performed in 20 (7.8%) patients at 8.2 ± 2.9 days after TAVR. Patients requiring PPI had smaller LVOT area (356.3 vs. 399.4 mm², p ≤ 0.011). Moreover, receiver operating characteristic statistics showed that LVOT area /annulus area possessed significantly higher predictive ability than LVOT area (c-statistic: 0.91 [95% confidence interval [CI]: 0.84-0.95] vs. 0.67 [95% CI: 0.57-0.77], p < 0.001). Multivariable analysis revealed that LVOT area /annulus area (odds ratio [OR]: 1.93 [95% CI: 1.38-2.71]; p < 0.001 per % of decreasing), the difference between membranous septum length and implantation depth (ΔMSID) (OR: 6.82 [95% CI 2.39-19.48]; p < 0.001 per mm of decreasing) and pre-existing complete right bundle branch block (CRBBB) (OR: 32.38 [95% CI2.30-455.63]; p ≤ 0.002) were independently associated with PPI. In our study, tapered-shape LVOT as well as short ΔMSID and pre-existing CRBBB were identified as independent predictors for PPI after TAVR. Higher valve implantation is required to minimize the risk of post-procedural PPI especially for patients with short MS length, pre-procedural CRBBB, or tapered-shape LVOT.