Upgrading expandable leadless pacemakers from single- to dual-chamber

Aims The aim of this analysis was to evaluate the upgradeability of a single-chamber leadless pacemaker (LP) to a dual-chamber system in patients indicated for a dual-chamber pacemaker. Methods and results A prospective, multicentre study evaluated the safety and performance of a dual-chamber LP. The study included patients with a prior ventricular LP to evaluate its upgradeability. Patients had an attempted atrial LP implant, and if successfully implanted, the LPs were paired to a dual-chamber pacing mode to evaluate upgrade success. Patients were followed for 12 months from the attempted atrial LP implantation. Among 35 patients with an attempted upgrade (62.9% male, average age 70 years), the most common primary indication was sinus node dysfunction (57.1%). Out of 35 patients, 91.4% had successful upgrades. The mean atrial device electrical measurements stabilized within 1 month from the procedure and remained stable through 12 months (capture threshold at 0.4 ms 0.8 ± 0.6 V, sense amplitude 4.5 ± 2.7 mV at 12 months). A total of five (14.3%) patients experienced seven complications, all of which were procedure-related. There were no device or procedure-related deaths. The total estimated battery longevity (accounting for time since implant) evaluated at 12 months was 11.3 ± 4.2 and 5.7 ± 2.6 years for the ventricular and atrial LPs, respectively. One patient required an atrial LP revision 10 months after implantation. The LP was retrieved and replaced. Conclusion These data confirm the feasibility, safety, and long-term effectiveness of adding an atrial LP in patients with a pre-existing ventricular LP to achieve dual-chamber leadless pacing.