Prevalence and Periprocedural Value of Current of Injury at the Implantation of a Passive Fixation Leadless Pacemaker

Current of injury (COI) predicts stability and acute improvement in electrical parameters in transvenous pacing or high-voltage leads; however, the periprocedural value of this marker in leadless pacemakers (LLPs) is unknown.

From March 2021 to October 2022, 66 consecutive Micra LLP pacemaker candidates were enrolled. Electrograms (EGMs) and electrical measures were acquired immediately after the deployment and 5 min after. The primary outcomes were an acute reduction in pacing threshold and, conversely, a need for device repositioning.

Fifty-one patients were included in the final analysis after excluding poor-quality EGMs and pacemaker-dependent cases (n = 15). COI was identified in 32 (62%). There were no differences in the initial electrical measures between the COI+ and COI- groups (p value = 0.33, 0.37, 0.89 for impedance, pacing threshold, and sensing, respectively). Notably, the capture threshold significantly improved only in the COI+ group within 5 min (p = 0.002). A subgroup analysis of COI+ revealed that the saddleback type of injury (Type 2) was associated with a more significant acute reduction in the capture threshold (p = 0.02). Repositioning occurred in three subjects, and acute dislodgment at the tug-test occurred in two patients, all from the COI- group.

COI is associated with an acute improvement of capture threshold, particularly when a Type 2 pattern is noted. The absence of injury, in contrast, could reflect inadequate fixation and a need for repositioning.