A leadless ventricular pacemaker providing atrioventricular synchronous pacing in the real-world setting: final results from the Micra AV Post-Approval Registry
C Garweg, J Chinitz, E Marijon, A Haeberlin, S Winter, S Iacopino, A Curnis, T Mela, M F El-Chami, P R Roberts, J P Piccini, K Stromberg, D H Fagan, N ClementyAbstract
Background/Introduction
Leadless pacemakers reduce complications associated with traditional transvenous pacemakers. The Micra AV leadless pacemaker is a single-device solution to provide atrioventricular synchronous pacing.
Purpose
To report final results of the worldwide Micra AV post-approval registry (PAR) through 3 years post implant.
Methods
The Micra AV PAR was a prospective single-arm observational study designed to assess safety and performance of Micra AV in the real-world setting. The primary endpoint of the study was to characterize the rate of pacemaker syndrome resulting in system revision at 3 years post-implant. A secondary objective of the study was to estimate the 3 year major complication rate related to the Micra AV system and/or procedure. In addition, the major complication and system revision rates through 3 years were compared to a historical cohort of 2,667 transvenous dual-chamber (TV-DC) pacing patients. Total AV synchrony index (sum of %AM-VP, %AM-VS, and AV conduction mode switch percentage) were also summarized.
Results
Micra AV was successfully implanted in 796 of 801 patients (99.4%) at 97 sites in 19 countries. Micra AV patients were older (74.1 vs. 71.1 years, P<0.0001) and had a higher incidence of renal disease (22.3% vs. 9.8%, P<0.0001) compared with TV-DC patients. Median follow-up duration was 38.9 months (IQR: 19.6 to 45.1 months). There were 7 pacemaker syndrome events requiring a system modification between 113-900 days post-implant for a 3 year rate of 1.0% (95% CI: 0.4% to 1.9%) (Figure). Of these 7 system modifications 3 patients received a CRT system, 2 patients received an alternate leadless pacing system, 1 patient received a dual chamber transvenous pacemaker system, and 1 patient received a single chamber atrial transvenous pacemaker system. The Micra AV system or procedure related major complication rate at 3 years was 4.9% (95% CI: 3.6%-6.6%) compared to 9.8% for TV-DC (HR: 0.49, 95% CI: 0.35-0.68, P<0.001). The system revision rate was 3.9% (95% CI: 2.7%-5.6%) for Micra AV patients and 8.1% for TV-DC patients (HR: 0.44, 95% CI: 0.30-0.65; P<0.001). Among the Micra AV system revisions, 27 were left in place and 7 were successfully removed between 1-688 days post-implant. Median ventricular pacing percentage was 81.3%. There were no system revisions requiring the removal of Micra AV due to infection. Median AV synchrony index was 84.9% overall (n=326 patients with data available for analysis) and was 76.8% among patients paced >90% (n=148).
Conclusions
The Micra AV leadless pacemaker was implanted with a high rate of success in patients with a high comorbidity burden, showing a significant reduction in major complications and system revisions relative to transvenous dual chamber pacemakers. Importantly, the occurrence of pacemaker syndrome requiring system modification remained low despite a high ventricular pacing burden.Rate of PM Syndrome Requiring Revision