Behavior of Leadless atrioventricular synchronous pacing during exercise.

Abstract

The leadless Micra AV pacemaker is designed to provide atrio-ventricular (AV) synchronous tracking by detecting the atrial contraction. Detection of the mechanical atrial signals can become challenging at fast sinus rate. The purpose of the study was to evaluate the AV synchronous performance at exercise in outpatients implanted with a Micra AV pacemaker. Patients were enrolled at least 1-month after a Micra AV implant and underwent a cycle test protocol. Serial device interrogations (each minute) and continuous electrocardiogram were collected to measure AV synchrony and determine maximum achieved sinus and ventricular rate for each patient. Additionally, the A1, A2, A3 and A4 accelerometer signal amplitudes were measured at start and peak of exercise. Thirty-five patients (mean age: 75.6 ± 13.4 years, 80% male) were enrolled in the study; 22 (64%) were predominantly ventricular paced (>90%) during exercise. The average AV synchrony was 90.4% in the entire cohort and 84.7% in patients with high degree AV block. The mean amplitude of the accelerometer signals increased significantly from start to peak of exercise: A1 (4.1 to 6.3 m/s2), A2 (2.4 to 3.8 m/s2) and A4 (4.5 to 7.6 m/s2) (all, p<0.01). The time from the VP-A2 decreased 25 ms for each 100 ms of R-R interval decrease. Maintaining AV synchrony during maximal exercise in elderly patients is achievable by adequate detection of atrial contraction at high sinus rates by the leadless Micra AV pacemaker. All components of the accelerometer signal increased, likely due to increased contractility related to exercise.