MARVEL 2: Atrial sensing algorithm with leadless pacemaker boosts atrioventricular synchrony
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PHILADELPHIA — Accelerometer-based atrial sensing with a novel, enhanced, automated algorithm in patients with atrioventricular block and a single-chamber leadless pacemaker in the right ventricle significantly improved atrioventricular synchrony, which led to significant improvements in stroke volume, according to data from the MARVEL 2 trial presented at the American Heart Association Scientific Sessions.
The study was simultaneously published in JACC: Clinical Electrophysiology.
Larry A. Chinitz, MD, Alvin Benjamin and Kenneth Coyle, Sr. Family Professor of Medicine and Cardiac Electrophysiology in the department of medicine, clinical director of cardiology, director of the Cardiac Electrophysiology and Heart Rhythm Center and director of the clinical electrophysiology fellowship program at NYU Langone Health, and colleagues analyzed data from 75 patients (mean age, 78 years; 40% women) from 12 centers with a history of atrioventricular block who had previously received or were undergoing implant with the leadless pacemaker (Micra, Medtronic). An enhanced downloadable algorithm was implemented within the leadless pacemaker to provide atrioventricular synchronous pacing (VDD) with mechanically sensing atrial contraction through the accelerometer.
“The algorithm was automatically downloaded and automatically created these measurements, was able to choose the optimal accelerometer vectors, set the thresholds for A3 and A4 [signals],” Chinitz said during the presentation. “It also had two additional features of mode switching. It was capable of mode switching to a VVI-40 mode to check for intrinsic conduction, and it also had importantly a rate response, a VVIR mode, so that at rates in excess of 90 to 95 bpm, it would switch to rate response pacing. ... The rate responsive mode allows the device to maintain heart rates appropriate for exercise.”
The primary efficacy endpoint was a sensed or paced ventricular beat within 300 ms after a P-wave confirmed by surface ECG for at least 70% of the confirmed P-waves. The primary safety endpoint was freedom from pauses for longer than two cardiac cycles and freedom from oversensing episodes that were induced by tachycardia that exceeded 100 bmp for longer than 3 minutes.
Of the patients in the study, 40 (mean age, 77 years; 55% women) had a predominant rhythm of complete atrioventricular block with normal sinus rhythm and were included in the primary efficacy analysis.
There were more patients in VDD pacing who had 70% or greater atrioventricular synchrony at rest compared with VVI-50 pacing (95% vs. 0%; P < .001). The percentage of atrioventricular synchrony increased from 26.8% (95% CI, 26.2-27.5) during VVI pacing to 94.3% (95% CI, 84.8-92.5) during VDD pacing.
Left ventricular outflow tract velocity time integral increased by 8.8% during VDD pacing.
All patients with the algorithm met the primary safety endpoint, as there were no instances of oversensing induced tachycardia and ventricular pauses.
“In my mind, this is a gamechanger,” Chinitz said during the presentation. “It allows us to use a leadless single-chamber device in patients with intrinsic atrial activity and resume AV synchrony without having to resort to a traditional lead-type pacemaker with its increased morbidity.” – by Darlene Dobkowski
References:
Chinitz LA, et al. Featured Science: EP. Presented at: American Heart Association Scientific Sessions; Nov. 16-18, 2019; Philadelphia.
Steinwender C, et al. JACC Clin Electrophysiol. 2019;doi:10.1016/j.jacep.2019.10.017.
Disclosures: The study was funded by Medtronic. Chinitz reports he is on the speaker’s bureau for Abbott, Biotronik and Medtronic and is a consultant/advisory board member for Medtronic. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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Vincent Y. See, MD
MARVEL 2 is an early study looking at use of the leadless Micra ventricular pacemaker to provide atrioventricular synchronous pacing in patients with normal sinus rhythm. The authors demonstrate that maintaining atrioventricular synchrony with an accelerometer-based algorithm is safe, as measured by lack of oversensed, inappropriate rate-responsive pacing, feasibly with maintenance of atrioventricular synchrony, and associated with improved LV outflow tract ejection velocity, as measured by echo. MARVEL 2 expands on current FDA-approved Micra indications for single-chamber ventricular pacing and the prior MARVEL study that demonstrated feasibility of atrioventricular synchronous pacing. While further data are needed to understand if we can improve clinical outcomes such as symptoms, HF class or atrial fibrillation burden, this seems to be a promising way of expanding single-chamber, leadless, ventricular pacing to maintain physiologic atrioventricular synchrony.
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