An AV-Synchronous Leadless Pacemaker with Electrical Far-Field Atrial Sensing in a Sheep Model

BACKGROUND: Ventricular leadless pacemakers offer a valuable alternative to conventional transvenous systems by markedly reducing complications related to leads and device pockets. However, current leadless ventricular devices either provide asynchronous pacing only or achieve AV synchrony (AVS) with variable consistency, largely influenced by the underlying sinus rate, the pacing indication, and the programmed pacing strategy. OBJECTIVE: To evaluate safety and efficacy of a new AVS leadless pacemaker system in a GLP animal study. METHODS: The LivIQ DX pacemaker, a sub 1-cc VDD implant with tine fixation and electrical far-field sensing of the p-wave, was implanted in nine sheep via jugular access in a GLP study. Safety was evaluated during the implant procedure, and via regular blood panels, ambulatory pacemaker data collection, and necropsy examination at 12 weeks post-implantation. Efficacy was assessed using R-wave amplitude, pacing capture threshold, and pacing impedance. AVS was evaluated at rest and during a stress test. RESULTS: The LivIQ was successfully implanted in all sheep with no serious adverse events. Electrical values were stable throughout the 12-week duration, with a mean p-wave amplitude of 71±39 μV, R-wave amplitude of 9.9±4.1 mV, pacing capture threshold of 0.8±0.4 V at 0.25 ms, and pacing impedance of 869±233 Ohms. All subjects were 100% AV-synchronous at rest during AsVp tracking and AVS was maintained up to 140 bpm during the stress test. There were no clinically significant observations at necropsy. CONCLUSION: This study highlights the safe implantation and reliable electrical performance of a novel leadless pacemaker, demonstrating high AVS in a chronic sheep model.