Long-Term Performance of Single-Chamber Atrioventricular-Synchronous Leadless Pacing: Results From 4 Years of Serial Follow-up.

INTRODUCTION: Micra AV enables atrioventricular (AV)-synchronous pacing by sensing atrial mechanical contraction (A4) using device's accelerometer. Short-term studies showed good AV synchrony (AVS), but long-term data are lacking. METHODS: Within the OPTIVALL cohort, we identified patients implanted with a first-generation Micra AV (June 2020-February 2024) who remained in sinus rhythm and programmed in VDD for ≥ 1 year. Device-derived AVS was collected annually (tracking index and total AVS = AM-VP + AM-VS) up to 4 years. A4 amplitude was recorded at each visit. A subgroup underwent 24-h Holter-ECG to assess ambulatory AVS at long-term follow-up. Atrial sensing had been optimized early after implant with no further adjustment at follow-up. RESULTS: Of 54 implanted patients, 44 met inclusion criteria. Median (IQR) total AVS remained stable over time: 90.6% (85.4%-93.6%), 90.6% (83.1%-92.1%), 89.2% (84.3%-92.2%), and 89.3% (86.2%-91.6%) at 1, 2, 3, and 4 years, respectively (p = 0.789). Median (IQR) tracking index was 94.3% (88.9%-97.1%), 93.0% (85.0%-98.0%), 90.2% (84.4%-98.0%), and 90.0% (87.0%-93.9%) (p = 0.059). Median (IQR) A4 signal amplitude was 3.1 (2.0-5.1), 5.1 (2.1-5.1), 3.7 (1.9-5.1), and 5.1 (2.5-5.1) m/s2 (p = 0.993). In 20 patients with 24-h Holter-ECG at 2.7 ± 1.1 years, ambulatory AVS was 85.5% (80.0%-90.7%) and was comparable to the 3-month value (87.9% (76.8%-93.1%); p = 0.811). CONCLUSIONS: When atrial sensing is optimized early, Micra AV can provide high and stable AV-synchronous pacing for up to 4 years, with preserved A4 signal amplitude.