Ventricular Pacing Inhibition After Dual-Chamber Leadless Pacing Associated With a Retained Right Ventricular Lead

An 88-year-old pacemaker-dependent man with a retained low-impedance, noise-producing right ventricular lead underwent implantation of a dual-chamber leadless pacemaker. On postoperative day 1, he developed recurrent syncope with pauses up to 13 s. Although stored electrograms from the index events were unavailable, post-event interrogation showed atrial pacing followed by ventricular safety pacing, and provocative testing supported persistent electrical coupling involving the retained lead. After reduction of temporary high-output settings and reprogramming to VDD, syncope did not recur during 12 months. Retained malfunctioning leads may mediate timing-dependent ventricular inhibition after dual-chamber leadless pacing.