Improvement of myocardial contractility with leadless endocardial single-lead atrial sensing ventricular pacing in patients with prolonged PQ interval.

Micra AV represents a leadless endocardial pacing system able to detect atrial contractions providing atrioventricular synchrony. A reduction of myocardial contractility may be detected in case of first-degree atrioventricular block (AVB). In six patients with first-degree AVB (PQ interval ≥220 msec) was evaluated the left ventricle global longitudinal strain (LV GLS) by speckle tracking (ST) echocardiography during single-lead atrial sensing ventricular pacing (VDD) stimulation as compared with spontaneous rhythm (SR), 24-48 h after Micra AV implantation. A statistically significant difference between the two modalities was observed (LV GLS during SR: -14.7% [interquartile range (IQR) 5.5], LV GLS during VDD pacing: -16.1% [IQR 5.2]; p value = 0.041). Our preliminary results suggest an improvement of myocardial contractility with VDD pacing as compared with SR.