Two-year outcomes of Micra AV leadless pacemakers in the Micra AV CED study

AIMS: Leadless pacing is a safe and effective alternative to transvenous pacing for bradycardia. Micra AV is a leadless, single-device solution that provides atrioventricular synchronous ventricular pacing therapy. Early results from the Micra AV CED study showed reductions in short-term complications associated with the Micra AV leadless pacemaker among US Medicare patients. The objective of this study is to compare chronic complications, re-interventions, and all-cause mortality at 2 years between patients implanted with a Micra AV leadless pacemaker and a traditional dual-chamber transvenous (DC-TV) pacemaker. METHODS AND RESULTS: Patients implanted with a Micra AV leadless pacemaker (n = 7552) or a DC-TV pacemaker (n = 110 558) in 2020 and 2021 were identified using device registration-linked Medicare administrative claims data. Competing risk models compared the unadjusted and propensity score overlap weight-adjusted complication, re-intervention, and all-cause mortality rates of Micra AV and DC-TV patients at 2 years. Micra AV patients had significantly more comorbidities (end-stage renal disease 14.9 vs. 2.0%, P < 0.0001; renal dysfunction 47.9 vs. 34.2%, P < 0.0001; diabetes 46.2 vs. 38.3%, P < 0.001; congestive heart failure 41.4 vs. 30.6%, P < 0.0001). Two years post-implant, Micra AV patients had lower complication rates [adjusted 5.3 vs. 9.6%, hazard ratio (HR): 0.54, 95% confidence interval (CI) 0.49-0.61, P < 0.0001] and lower re-intervention rates (adjusted 3.5 vs. 5.6%, HR: 0.62, 95% CI 0.54-0.72, P < 0.0001) than DC-TV patients. Upgrades to cardiac resynchronization therapy were low in both groups (adjusted 1.6 vs. 1.7%, P = 0.40), as were Micra AV upgrades to a dual-chamber system (adjusted 1.4%). All-cause mortality rates remained higher in Micra AV than in DC-TV patients (unadjusted HR: 2.48, 95% CI 2.35-2.62, P < 0.0001; adjusted HR: 1.53, 95% CI 1.44-1.62, P < 0.0001). CONCLUSION: Patients implanted with Micra AV had lower complications and re-intervention rates at 2 years than patients implanted with a traditional DC-TV pacemaker. All-cause mortality remained higher in Micra AV patients, likely due to their higher comorbidity burden and other differences in baseline characteristics. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov ID NCT04235491.