(P080) REAL-WORLD EXPERIENCE ON THE SAFETY AND EFFECTIVENESS OF MICRA TPS IN PATIENTS WITH PRE-EXISTING IN SITU CIEDS

Background: Patients with pre-existing cardiac implantable electronic devices (CIED) were excluded from the Micra pre-market study; however, this group of patients might benefit from a leadless pacemaker especially when a lead fails or after incidence of system-related infections.

Objective: To determine the outcome of patients with a pre-existing CIED or lead that remains in situ at the time of Micra implant attempt.

METHODS AND RESULTS: Patients who had a pre-existing CIED and/or lead at the time of Micra implantation attempt were identified from the Micra Post-Approval Registry and Micra Acute Performance studies. Baseline characteristics were summarized. A Fine-Gray competing risk model was used to compare risk for major complication through 24 months for patients with and without a pre-existing CIED. Of 2323 patients, 111 patients had a pre-existing CIED or lead at the time of Micra implantation attempt that remained in situ. Types of pre-existing devices included 81 pacemakers (45 single-chamber, 32 dual-chamber, 4 unknown), 10 ICDs (2 single-chamber, 2 dual-chamber, 6 unknown), 10 CRTs (6 CRT-P, 4 CRT-D), 3 of unknown type, and 7 patients had only leads remaining. Patients with pre-existing devices were younger and less likely to have a pacing indication of bradyarrhythmia with atrial fibrillation compared to patients without pre-existing devices (p < 0.001 for both). Patients with prior devices were more likely to have a condition precluding implant of a transvenous pacemaker (67.6% vs. 21.3%, p< 0.001). Presence of a pre-existing CIED did not impact outcome of the Micra implant procedure: implant success was >99% for both cohorts. Mean follow-up duration was 21.2 ± 14.3 months (range 0-56) for pre-existing devices patients and 23.3 ± 15.8 months (range 0-62) for other patients. Rate of major complications through 24 months was 1.8% for patients with and 3.8% for patients without prior devices (p = 0.36). No major complications were related to device malfunction or device-device interaction. There were 6 system revisions in 4 patients with preexisting devices and 52 revisions in 51 patients without preexisting devices. Pacing thresholds for patients with and without prior devices were similar at implant (0.72 and 0.63, respectively; p = 0.31) and remained stable through 12 months.

Conclusion: Micra can be safely and successfully implanted in patients with a pre-existing CIED remaining in situ. It should be considered a treatment option for patients in whom CIED extraction may be deemed high risk.