Purpose: Leadless pacemaker (LP) extraction is a relatively new field with limited operator experience. We sought to report a comparison of retrieval process for Nanostim vs Micra transcatheter LPs.
Methods: The list of retrievals for the Micra transcatheter pacemaker system (TPS) was obtained from Medtronic whereas Nanostim data was obtained from centers that participated in the Leadless II study. Details of retrieval such as indication, days post implantation, complications, and post procedure device management were obtained from the manufacturer database for each site, and any missing details were obtained from individual operators. Extractions performed on the same day were labeled as "Early" and thereafter were labeled as "Late."
Results: A total of 113 retrievals were attempted (73 in Nanostim and 40 in Micra TPS). The most common reasons for retrieval were battery advisory and inadequate pacing threshold (n = 16) for Nanostim and Micra, respectively. Success rate in Nanostim group was around 90% (66/73) compared with 100% in Micra group (p = 0.049). Late retrieval occurred in 50% of Micra TPS cases (20/40) compared with 100% of Nanostim LP cases. Median time to extraction was 46 days for Micra TPS and 256 days for Nanostim LP (p < 0.001). Rate of serious adverse events with Nanostim extraction was 3% (n = 2/73).
Conclusion: Overall, LP extraction is feasible and safe to perform irrespective of the duration and type of the device.
Keywords: Leadless; Micra; Nanostim; Pacemaker; Pacing threshold; Snare.