Outcomes of leadless pacemaker implantation after cardiac surgery and transcatheter structural valve interventions

Introduction: Permanent pacing indications are common after cardiac surgery and transcatheter structural valve interventions. Leadless pacemakers (LPs) have emerged as a useful alternative to transvenous pacemakers. However, current commercially available LPs are unable to provide atrial pacing or cardiac resynchronization and relatively little is known about LP outcomes after cardiac surgery and transcatheter valve interventions. Methods: This retrospective study included patients who received a Micra VR (Micra (TM) MC1VR01) or Micra AV (Micra (TM) MC1AVR1) (Medtronic) leadless pacemaker following cardiac surgery or transcatheter structural valve intervention between September 2014 and September 2022. Device performance and clinical outcomes, including ventricular pacing burden, ejection fraction, and need for conversion to transvenous pacing systems, were evaluated during follow-up. Results: A total of 78 patients were included, of whom 40 received a Micra VR LP implant, and 38 received a Micra AV LP implant. The mean age of the cohort was 65.9 +/- 17.9 years, and 48.1% were females. The follow-up duration for the entire cohort was 1.3 +/- 1.1 years: 1.6 +/- 1.3 years for the Micra VR group and 0.8 +/- 0.5 years for the Micra AV group. Among the cohort, 50 patients had undergone cardiac surgery and 28 underwent transcatheter structural valve interventions. Device electrical performance was excellent during follow-up, with a small but clinically insignificant increase in ventricular pacing threshold and a slight decrease in pacing impedance. The mean right ventricle pacing (RVP) burden significantly decreased over time in the entire cohort (74.3% +/- 37.2% postprocedure vs. 47.7% +/- 40.6% at last follow-up, p <.001), and left ventricle ejection fraction (LVEF) showed a modest but significant downward trend during follow-up (55.0% +/- 10.6% vs. 51.5% +/- 11.2% p <.001). Patients with Micra VR implants had significantly reduced LVEF during follow-up (54.1% +/- 11.9% vs. 48.8% +/- 11.9%, p =.003), whereas LVEF appeared stable in the Micra AV group during follow-up (56.1% +/- 9.0% vs. 54.6% +/- 9.7%, p =.06). Six patients (7.7%) required conversion to transvenous pacing systems, four who required cardiac resynchronization for drop in LVEF with high RVP burden and two who required dual-chamber pacemakers for symptomatic sinus node dysfunction. Conclusion: Leadless pacemakers provide a useful alternative to transvenous pacemakers in appropriately selected patients after cardiac surgery and transcatheter structural valve interventions. Device performance is excellent over medium-term follow-up. However, a significant minority of patients require conversion to transvenous pacing systems for cardiac resynchronization or atrial pacing support, demonstrating the need for close electrophysiologic follow-up in this cohort.