Leadless atrioventricular synchronous pacing – Four years real life experience in comparison to data of the VVI-System

Introduction:
The Micra AV™ intracardiac leadless pacing system has been introduced and implemented into clinical routine in Germany in July 2020. Size and composition of this second-generation leadless pacemaker are the same as the available MICRA VVI system. Feasibility, implantation safety and procedural success are assumed to be similar than proven in the setting of controlled studies with the first generation device. Therefore, we aimed to report our first single center four years follow-up (FU) data in comparison with the results of the prospective controlled Micra VR™ study.

Methods:
After MicraAV™ implantation pacemaker interrogation was performed one to seven days after implantation and during FU (one and 3 months, than every 6 six month up to 4 years). Data were assessed in a real-life setting and compared with existing data of a controlled prospective trial. Furthermore, we investigated the rate of AV-synchronous Stimulation (AVSR).

Results:
The MicraAV™ implantation was successful in 95/95 patients (53% male; mean age: 82,4±5,3) without procedure or device-related major complications.

The average acute thresholds, sensing and impedance after system release were:  0.59±0.14V@0.24ms; 9,59±5,65mV and 768±196 Ohm

During follow up of up to four years, neither pacemaker failure nor infections were reported. Measurements were reevaluated for “long-term” thresholds, sensing and impedance: 0,52 ± 0,17 V @ 0.24 ms; 17,25 ±4,76 mV and 560 ± 57 Ohm.

During FU of up to 24 month, no significant changes were detectable.  

During Follow up we detected a median AV-synchronous stimulation rate (AVSR) of 74%.

Conclusion:
In a real-life setting, the implantation of the leadless Micra AV™ system demonstrated a high rate of implantatiom success without major complications. We were also able to show stable system parameters in the clinical setting during short term follow up. We were able to reconfirm the positive results of the IDE trial in this clinical scenario.

After four year experience it is obvious that in MICRA AV-patients the focus has moved from implantation to patient-selection and follow-up. In real life the AV-synchronous stimulation rate seems to be the hardest challenge.