Leadless vs. transvenous single-chamber ventricular pacing in the Micra CED study: 2-year follow-up

Abstract

Aims: Clinical trials have demonstrated the safety and efficacy of the Micra leadless VVI pacemaker; however, longer-term outcomes in a large, real-world population with a contemporaneous comparison to transvenous VVI pacemakers have not been examined. We compared reinterventions, chronic complications, and all-cause mortality at 2 years between leadless VVI and transvenous VVI implanted patients.

Methods and results: The Micra Coverage with Evidence Development study is a continuously enrolling, observational, cohort study of leadless VVI pacemakers in the US Medicare fee-for-service population. Patients implanted with a leadless VVI pacemaker between March 9, 2017, and December 31, 2018, were identified using Medicare claims data linked to manufacturer device registration data (n = 6219). All transvenous VVI patients from facilities with leadless VVI implants during the study period were obtained directly from Medicare claims (n = 10 212). Cox models were used to compare 2-year outcomes between groups. Compared to transvenous VVI, patients with leadless VVI had more end-stage renal disease (12.0% vs. 2.3%) and a higher Charlson comorbidity index (5.1 vs. 4.6). Leadless VVI patients had significantly fewer reinterventions [adjusted hazard ratio (HR) 0.62, 95% confidence interval (CI) 0.45-0.85, P = 0.003] and chronic complications (adjusted HR 0.69, 95% CI 0.60-0.81, P < 0.0001) compared with transvenous VVI patients. Adjusted all-cause mortality at 2 years was not different between the two groups (adjusted HR 0.97, 95% CI 0.91-1.04, P = 0.37).

Conclusion: In a real-world study of US Medicare patients, the Micra leadless VVI pacemaker was associated with a 38% lower adjusted rate of reinterventions and a 31% lower adjusted rate of chronic complications compared with transvenous VVI pacing. There was no difference in adjusted all-cause mortality at 2 years.

Trial registration: ClinicalTrials.gov NCT03039712.

Keywords: Complications; Leadless pacemakers; Survival; System reintervention; Transvenous pacemakers.

Graphical Abstract

Figure 1

Cohort formation flow chart. Chart showing patient selection and exclusion criteria and the numbers of patients excluded/included at each step. CIED, cardiac implantable electronic device.

Figure 2

Adjusted time to event plots for device reinterventions, chronic complications and mortality out to 2 years of follow-up in patients treated with leadless VVI vs. transvenous VVI pacing. (A) Hazard ratio and cumulative incidence function for 2-year device reintervention based on the Fine–Gray competing risk model. (B) Hazard ratio and cumulative incidence function for 2-year chronic complications based on the Fine–Gray competing risk model. (C) Hazard ratio and patient mortality rates based on the Cox proportional hazards model. CI, confidence interval.