Impact on preoperative estimation of atrial mechanical amplitudes with vdd leadless pacemaker

Abstract Background It would be useful to determine whether the device can sense the mechanical atrial amplitude (A4) before the implantation of a VDD leadless pacemaker (Micra AV^RT, Medtronic, US). Purpose To evaluate whether identifiable A4 is associated with preoperative echocardiographic parameters. Methods Echocardiographic measurements were performed to quantify atrial motion of the interventricular septum in patients who received a leadless pacemaker implantation. We visually divided the septum into five segments from the base to the apex. As shown in Figure 1, the myocardial velocity of each segment measured on tissue doppler imaging (TDI) was defined as EV1, EV2, EV3, EV4, and EV5 (m/s), respectively. After the implantation, amplitude of A4 was compared to the local EV. Results We retrospectively analyzed 30 patients who had Micra AV implanted into the right ventricular septum by imaging examination and had measurable EV for each segment. The mean age was 82.3±7.8 years, 15 (50%) patients were female, 11 (37%) patients had organic heart disease, and 23 (77%) patients had atrial ventricular block. The mean LVEF and A4 amplitude were 60.4 ± 8.9% and 2.7 ± 1.8 m/s^2, respectively, and the mean atrial mechanical sensing rate (AMSR) was 79.9±24.0%. The A4 amplitude was positively correlated to the AMSR (r=0.48), while the AMSR was significantly better in patients with A4 amplitude over 1.0 m/s^2 (88.0 ± 10.4% vs. 41.0 ± 33.6%, p=0.04). The A4 amplitude was correlated to the EV of the implantation site estimated from fluoroscopy and echocardiography (r=0.62) in Figure 2. 24 patients had local EV over 3.0 cm/s, and among them, 22 (92%) patients had A4 amplitude over 1.0 m/s^2. Conclusion Local EV over 3.0 cm/s, as determined by preoperative echocardiography, might predict high-frequency AMSR.