Comparison of first- and second-generation leadless pacemakers in patients with sinus rhythm and complete atrioventricular block.

INTRODUCTION: The efficacy and safety of leadless cardiac pacemakers (LPMs) as an alternative to conventional transvenous cardiac pacing have been largely reported. The first generation of the MicraTM transcatheter pacing system (VR; Medtronic) was able to provide single-chamber VVI(R) pacing mode only, with a potential risk of pacemaker syndrome in sinus rhythm patients. A second-generation system (AV) now provides atrioventricular synchrony through atrial mechanical (Am) sensing capability (VDD mode). OBJECTIVE: We sought to compare VR and AV systems in sinus rhythm patients with chronic ventricular pacing (Vp) for complete atrioventricular block. METHODS: All consecutive patients implanted with an LPM in our department for complete atrioventricular block were retrospectively screened. Patients with atrial fibrillation, sinus dysfunction, or Vp burden <20% at 1 month postimplantation were excluded. Patients were systematically followed with a visit at 1 month, and then at least once a year. RESULTS: A total of 93 patients-45 VR (2015-2020) and 48 AV (2020-2021)-were included. VR and AV patients had similar baseline characteristics, except for VR patients being older (80 ± 8 vs. 77 ± 9 years, p = 0.049). The mean Vp burden was 77% in the VR and 82% in the AV group (p = 0.38). In AV patients, the median AV synchronous beats rate was 78%, with 65% having a >66% rate. An E/A ratio <1.2 as measured on echocardiography was the only independent predictor of accurate atrial mechanical tracking (p = 0.01). One-year survival rate was similar in both groups. Five patients in the VR and 0 in the AV group eventually developed pacemaker syndrome within 1 year post-implantation (p = 0.02). CONCLUSION: In sinus rhythm patients with chronic Vp for complete atrioventricular block implanted with an LPM, the atrial mechanical sensing algorithm allowed significant atrioventricular synchrony in most patients and was associated with no occurrence of-otherwise rare-pacemaker syndrome.

Leadless cardiac pacing: Results from a large single-centre experience.

BACKGROUND: The efficacy and safety of leadless cardiac pacing as an alternative to conventional transvenous cardiac pacing in selected patients have been widely reported. AIM: To report the experience of a high-volume implantation centre with older and new generations of leadless pacemakers. METHODS: This retrospective observational study included the first consecutive 400 patients who underwent implantation of a leadless pacemaker in our centre. Complications and electrical parameters were evaluated during follow-up, comparing patients implanted with first-generation (Micra™ VR) and second-generation (Micra™ AV) leadless pacemakers (Medtronic, Minneapolis, MN, USA). Data were collected by a review of medical files. RESULTS: Among 400 procedures, there were 328 Micra™ VR pacemakers and 72 Micra™ AV pacemakers implanted, followed for a median of 16 months (694 patient-years). The mean age was 77 years and both groups had a high burden of co-morbidities. Implantation success rate was 99.5%. A total of 87.5% of patients were discharged the day after the procedure. The pacing threshold remained stable and<2V in 96.5% of all patients. The perioperative complication rate at 30 days was 3.5%. Outcomes were similar between the two groups. CONCLUSION: Leadless cardiac pacing is a safe and efficient alternative to conventional transvenous cardiac pacing.