Atrial helix-fixation leadless pacemaker: real-world single-chamber implant experience

Abstract

Background: Single -chamber ventricular leadless pacemakers (LPs) are well established. A dual-chamber LP system has recently become available with distinct atrial and ventricular devices. Single-chamber atrial pacing with transvenous devices is infrequent due to future upgrade concerns. This multi-center study evaluated the initial real-world use of the atrial LP by itself to treat isolated sinus node dysfunction (SND).

Methods: SND patients with normal PR interval and AV conduction to be implanted with atrial LPs after commercial US release were consecutively included. Procedural characteristics were evaluated, and electrical parameters were measured during pre-fixation mapping, post-fixation tether mode, after LP release, and before patient discharge. Acute, 30-day procedure- or device-related complications were noted.

Results: Aveir AR devices were implanted per standard local practice (N = 75 patients; 3 centers; 72 ± 13 years; 52% male; 92% de novo) with 100% success and placed predominantly in the right atrial appendage base (83%). The total procedure duration (from first incision to final suture) was 36 ± 33 min and the cumulative fluoroscopy duration was 7 ± 8 min. Pre-fixation mapping made repositioning unnecessary in 95% of implants. Pacing capture threshold at 0.4 ms pulse width, sensed amplitude, and impedance values of 0.6 ± 0.6 V, 2.9 ± 1.5 mV, and 329 ± 46 Ω, respectively, were measured prior to patient discharge. Capture threshold and sensed amplitude had improved significantly from LP release to patient discharge. No acute complications were observed.

Conclusion: This initial real-world experience implanting the helix-fixation, single-chamber, atrial LP in SND patients demonstrated safe and efficient implantation, clinically acceptable electrical metrics, and no acute complications.

Keywords: Atrial pacemaker; Aveir; Helix fixation; Implant procedure; Leadless pacemaker; Pacemaker complications.

Fig. 1

Aveir AR atrial leadless pacemaker device. The atrial LP features a dual-helix fixation mechanism with an electrically active inner helix (cathode) and passive outer helix. Three radial sutures resist rotation. The LP case is partially parylene-coated for electrical isolation, with the remaining uncoated proximal end serving as the anode. A docking button on the proximal end interfaces with the delivery and retrieval catheters

Fig. 2

Fluoroscopic images demonstrate an example atrial LP delivery. A, B The implant site is first selected using contrast agent with the protective sheath still in place. C The sheath is retracted, and electrical viability of the site is verified. D The LP helix is screwed into the tissue. E The LP is undocked in tether mode prior to release, and a deflection test verifies fixation stability. F–G The LP is released, and catheter removed. RAO, right anterior oblique view; LAO, left anterior oblique view

Fig. 3

Intra- and post-procedural changes in electrical measurements. A Pacing capture thresholds at 0.4 ms pulse width, B sensed amplitudes, and C pacing impedances are shown. Time-points include pre-fixation mapping, post-fixation tether mode, after LP release, and prior to patient discharge. Asterisks indicate statistically significant changes from release to discharge