Prophylactic Permanent Pacemaker in Patients With Right Bundle Branch Block Undergoing Transcatheter Aortic Valve Implantation

BACKGROUND Transcatheter aortic valve implantation (TAVI) is standard of care treatment for patients with severe aortic stenosis ≥ 75 years and/or not eligible for surgical aortic valve replacement 1. There are two types of prosthetic valves: balloon expandable (BE) and self-expandable (SE) types with their distinct features 2. The TAVI-procedure and preexisting conditions in this population entails a risk of permanent pacemaker implantation following TAVI due to conduction disturbances related to the valve implantation and valve type (BE vs. SE). The rate of permanent pacemaker implantation after TAVI is between 2.3 - 36 % depending on valve type and pre-existing conditions3. Major risk factors are right bundle branch block (RBBB), left ventricular outflow track calcification, deeper valve implantation, and SE valves4. Pre-existing RBBB in patients undergoing TAVI occurs in 10% of the cases and it is associated with poor outcome5 in terms of higher pacemaker rate and mortality. Advanced conduction disturbances in patients with pre-existing RBBB occur within three days after the TAVI-procedure6. Hence, pre-existing RBBB is a major risk factor in the TAVI-population with higher mortality7 and needs special attention in peri-operative care. Current European Society Cardiology guidelines do not recommend prophylactic pacemaker implantation in patients without indication for permanent pacing8. However, cardiac pacing is associated with a risk of complications and development of heart failure9, and there is no randomized trial demonstrating a benefit of prophylactic pacemaker implantation in patients with pre-existing RBBB. Although previous observational data suggest prophylactic pacemaker implantation in patients with pre-existing RBBB shortens the TAVI procedure and prevents rehospitalization due to heart block10. Hence, there is a gap in knowledge regarding the outcome of prophylactic permanent pacemaker implantation in patients undergoing TAVI with pre-procedural RBBB and additional risk factors for need of post-procedural permanent pacing. This study aims to evaluate the clinical outcome and safety of prophylactic pacemaker implantation in this high-risk patient group versus a conservative strategy in a randomized clinical trial.

PURPOSE To evaluate safety and outcomes of prophylactic permanent pacemaker implantation in patients with RBBB undergoing TAVI.

HYPOTHESIS Prophylactic permanent pacemaker implantation reduces composite primary outcome in patients with RBBB undergoing TAVI.