Dual-chamber leadless pacing: Atrioventricular synchrony in preclinical models of normal or blocked atrioventricular conduction

Background: Dual-chamber leadless pacemakers (LPs) require robust communication between distinct right atrial (RA) and right ventricular (RV) LPs to achieve atrioventricular (AV) synchrony. Objective: The purpose of this preclinical study was to evaluate a novel, continuous implant-to-implant (i2i™) communication methodology for maintaining AV-synchronous, dual-chamber DDD(R) pacing by the 2 LPs. Methods: RA and RV LPs were implanted and paired in 7 ovine subjects (4 with induced complete heart block). AV synchrony (% AV intervals <300 ms) and i2i communication success (% successful i2i transmissions between LPs) were evaluated acutely and chronically. During acute testing, 12-lead electrocardiographic and LP diagnostic data were collected from 5-minute recordings, in 4 postures and 2 rhythms (AP-VP and AS-VP, or AP-VS and AS-VS) per subject. Chronic i2i performance was evaluated through 23 weeks postimplant (final i2i evaluation period: week 16–23). Results: Acute AV synchrony and i2i communication success across multiple postures and rhythms were median [interquartile range] 100.0% [100.0%–100.0%] and 99.9% [99.9%–99.9%], respectively. AV synchrony and i2i success rates did not differ across postures (P = .59, P = .11) or rhythms (P = 1, P = .82). During the final i2i evaluation period, the overall i2i success was 98.9% [98.1%–99.0%]. Conclusion: Successful AV-synchronous, dual-chamber DDD(R) leadless pacing using a novel, continuous, wireless communication modality was demonstrated across variations in posture and rhythm in a preclinical model.