Temperature-based rate response in a leadless pacemaker system

Background: A new dual-chamber leadless pacemaker (DR-LP) system, composed of 2 implantable devices in the right ventricle and right atrium, uses a less common temperature-based rate-response sensor. There is a need to understand the effectiveness of the rate response during exercise in both the ventricular (VR-LP) and atrial (AR-LP) devices.

Objective: We sought to determine whether temperature-based rate-responsive pacing is proportional to metabolic workload during an exercise test in a leadless pacemaker system.

Methods: After 6 weeks of implantation, we administered a treadmill exercise protocol to eligible participants concurrently enrolled in the LEADLESS II-Phase 2 and Aveir DR i2i studies. Programmed settings were optimized after a prior 6-minute walk test. We evaluated the ventricular and atrial rate-response sensors in participants implanted with the VR-LP and DR-LP system, respectively. For each device, the normalized slopes of sensor-indicated rate vs metabolic workload were aggregated across all analyzable patients. If the mean slope's 95% confidence interval (CI) fell within the prespecified 0.65 and 1.35 acceptance range, the rate response was considered proportional to metabolic demand.

Results: Seventeen participants had a mean ventricular rate-response slope of 0.93 ± 0.29 (CI, 0.78-1.08), which fell within the acceptance criteria (P = .001). Twenty participants had a mean atrial rate-response slope of 0.91 ± 0.28 (CI, 0.78-1.05), also falling within the prespecified criteria (P < .001).

Conclusion: The temperature-based sensor in a dual-chamber leadless pacemaker system was shown to be effective at modulating pacing rate in response to increased metabolic demand for right ventricular and atrial devices.

Gov identifier: NCT04559945 (LEADLESS II-Phase 2 study) and NCT05252702 (Aveir DR i2i study).