2.1. MARVEL 2

The MARVEL 2 study was a prospective, nonrandomized, multicenter clinical trial. ⁴ The primary aim of the MARVEL 2 study was to confirm the ability of a downloaded algorithm to time ventricular pacing to atrial activity (VDD pacing) by mechanically sensing atrial contraction using the accelerometer in the Micra VR leadless pacemaker previously implanted in the right ventricle. The primary efficacy objective was to demonstrate the superiority of the MARVEL 2 algorithm to provide AVS pacing relative to VVI pacing in patients with persistent third degree AV block and normal sinus node function at rest. While at the study clinic, patients wore a Holter while resting for 20 min and performing the following maneuvers for 2 min each: laying in supine position, laying on left side, laying on right side, sitting, standing, walking slowly, and walking vigorously. For purposes of this analysis, AVS was manually evaluated for each cardiac cycle during these activities and defined as a paced or sensed ventricular beat within 300 ms following a surface ECG confirmed P‐wave (see Supporting Information for details). The percentage of AVS beats was then computed during these activities for patients with a predominant rhythm of third degree AV block and normal sinus function.

In the MARVEL 2 study, %AM‐VP was derived by computing the percentage of ventricular events where an atrial mechanical detection preceded a ventricular paced event from the device markers recorded on a specialized Holter monitor capable of storing accelerometer waveforms, electrograms (EGMs), and device markers. The study protocol was approved by the ethics committee at each participating institution and all patients provided written informed consent.