Cardiology, well into the age of leadless pacemakers, could be headed for an age of leadless pacemaker systems in which various pacing functions are achieved by multiple implants that “talk” to each other.
Even now, a leadless two-part pacemaker system has shown it can safely achieve atrioventricular (AV) synchrony in patients with standard indications for a dual-chamber device, at least over the short term, suggests a prospective observational study. Currently available leadless pacemakers can stimulate only the right ventricle.
Experienced operators achieved a 98% implantation success rate in 300 patients who received an investigational dual-chamber leadless system, the AVEIR DR i2i (Abbott).
Its two separately implanted miniature pulse generators achieve AV synchrony via “beat-to-beat wireless bidirectional communication,” Daniel J. Cantillon, MD, said when presenting the study at the annual scientific sessions of the Heart Rhythm Societyin New Orleans.
The system seemed to work well regardless of the patient’s body orientation. “Sitting, supine, left lateral, right lateral, standing, normal walk, fast walk – we demonstrated robust AV synchrony in all of those positions and with movement,” said Dr. Cantillon, of the Cleveland Clinic.
Should the device be approved, it could “expand the use case for leadless cardiac pacing” to include atrial-only, ventricular-only, fully functional dual-chamber pacing scenarios.”
Dr. Cantillon is senior author on the study’s online publication in the New England Journal of Medicine, timed to coincide with his HRS presentation, with first author Reinoud E. Knops, MD, PhD, Amsterdam University Medical Center.
“The electrical performance of both the atrial and ventricular leadless pacemakers appears to be similar to that of transvenous dual-chamber pacemakers,” the published report states.
More data needed
The study is important and has “significant implications for our pacing field,” Jonathan P. Piccini, MD, MHS, said in an interview. It suggests that “dual-chamber pacing can be achieved with leadless technology” and “with a very high degree” of AV synchrony.
“Obviously, more data as the technology moves into clinical practice will be critical,” said Dr. Piccini, who directs cardiac electrophysiology at Duke University Medical Center, Durham, N.C. “We will also need to understand which patients are best served by leadless technology and which will be better served with traditional transvenous devices.”
The AVEIR DR i2i system consists of two leadless pulse generators for percutaneous implantation in the right atrium and right ventricle, respectively. They link like components of a wireless network to coordinate their separate sensing and rate-adaptive, AV-synchronous pacing functions.
The right ventricular implant “is physically identical to a commercially available single-chamber leadless pacemaker” from Abbott, the published report states.
Leadless pacemaker systems inherently avoid the two main sources of transvenous devices’ major complication – infection – by not requiring such leads or surgery for creating a pulse-generator subcutaneous pocket.
The first such systems consisted of one implant that could provide single-chamber ventricular pacing but not atrial pacing or AV synchronous pacing. The transcatheter single-chamber leadless Micra (Medtronic) for example, was approved in the United States in April 2016 for ventricular-only pacing.
A successor, the Micra AV, approved in 2020, was designed to simulate AV-synchronous pacing by stimulating the ventricle in sequence with mechanically sensed atrial contractions, as described by Dr. Cantillon and associates. But it could not directly pace the atrium, “rendering it inappropriate for patients with sinus-node dysfunction.”
The AVEIR DR i2i system doesn’t have those limitations. It was, however, associated with 35 device- or procedure-related complications in the study, of which the most common was procedural arrhythmia, “namely atrial fibrillation,” Dr. Cantillon said.
Atrial fibrillation can develop during implantation of pacemakers with transvenous leads but is generally terminated without being considered an important event. Yet the study classified it as a serious complication, inflating the complication rate, because “the patients had to be restored to sinus rhythm so we could assess the AV synchrony and also the atrial electrical performance,” he said.
Some of the devices dislodged from their implantation site within a month of the procedure, but “all of those patients were successfully managed percutaneously,” said Dr. Cantillon.
“The 1.7% dislodgement rate is something that we will need to keep an eye on, as embolization of devices is always a significant concern,” Dr. Piccini said. Still, the observed total complication rate “was certainly in line” with rates associated with conventional pacemaker implantation.