Optimizing atrial sensing parameters in leadless pacemakers: Atrioventricular synchrony achievement in the real world

Background: Performance of the leadless pacemaker capable of atrioventricular (AV) synchronous pacing in de novo patients warrants further investigation.

Objective: The aims of this study were to assess what programming changes are needed to achieve proper atrial tracking and to study the percentage of AV synchrony (AVS) the device can provide under real-world conditions.

Methods: Consecutive patients undergoing Micra AV implantation between June 2020 and November 2021 were studied. Reprogramming of atrial sensing parameters during follow-up was performed by following device counters. AVS was studied with an ambulatory 24-hour Holter monitor and automatically analyzed by an electrocardiogram delineation system. The primary end point was AVS ≥85% of total cardiac cycles during 24-hour Holter electrocardiogram monitoring.

Results: Thirty-one patients who remained in VDD mode were studied, and all of them required manual reprogramming. The automatic A3 window end was deactivated, and a fixed and short value was set in all patients throughout follow-up. AVS significantly increased from 68.7% ± 14.7% at 24-hour follow-up to 83.9% ± 7.4% at 1-month visit (P = .001). At 1-month visit, shorter A3 window end time (P = .019), higher A4 threshold (P = .011), and deactivation of the automatic A3 window (P = .054) were independently related to higher AVS. A total of 2,291,953 Holter-recorded cardiac cycles were analyzed. Median AVS during 24-hour daily activities was 87.6% (interquartile range 84.5%-90.6%). Twenty of 26 patients (79.6%) reached AVS ≥85% of cardiac cycles.

Conclusion: High rates of AVS can be achieved in real-world patients undergoing leadless pacing. Manual reprogramming of the atrial sensing parameters is essential to optimize mechanically sensed atrial tracking.