Introduction:

            The Micra™ transcatheter pacing system (TPS) has been implemented into clinical routine for more than 3 years. The primary recipients are patients (pts) in need for VVI pacing due to bradycardia in the setting of atrial fibrillation (AF). Feasibility, implantation safety and acute success have been proven in the setting of controlled studies. However, few data exist on long term device performance, clinical parameters and RV pacing demand during long-term follow-up (FU).  

Objective:

            We sought to analyze real-life and post-implantation data on TPS from two large German TPS implanting centers. Therefore, we report on acute success rates, device performance during long-term FU, alternative indications for TPS implantation and clinical data.

Methods:

            In two centers 129 patients (pts) (52 women; age: 80±9 y) underwent successful TPS implantation. All procedures were performed in deep sedation. Pacemaker interrogation was performed at discharge and during FU (1; 12, 24, 36 and 48 month). Furthermore, left ventricular ejection fraction (LVEF) and RV pacing demand was evaluated.

Results:

            Indication for TPS implantation in 100 out of 129 (78%) pts was permanent or intermittent AV-Block III° in the setting of persistent atrial fibrillation. In 29 (22%) pts TPS was implanted for other indications: 27 pts received TPS for sick-sinus-syndrome accompanied with severe comorbidities (e.g. end-stage renal failure) or anatomical abnormalities including 1 child, 2 pts showed sporadic occurrence of hypersensitive carotid syndrome and asystole. In all 29 pts a low RV pacing demand was expected.

The average procedure duration was 60±31 min. The average acute values after system release were: threshold: 0.61±0.18V/0.24ms; sensing: 9.4±0.6mV and impedance: 652±160Ohm. During FU of 871±319 days neither pacemaker failure, nor infections were reported. Further, non of the device values showed significant changes during FU. Although, no impairment of LVEF during FU occurred (LVEF before TPS implantation: 55%±8% vs. 56%±7%; p=0.28) there is an increase in RV pacing demand (34±37 vs. 50±42; p=0.5) over time.        

Two patients died from non-cardiac causes and 1 patient experienced worsening of left ventricular function and subsequently underwent CRT implantation.

Conclusion:

            This large two center German cohort experience shows that leadless TPS implantation is not only safe acutely but also delivers stable long-term device performance. Therefore, TPS is a valuable alternative for pts with comorbidities or anatomical obstacles who may even not fulfill the typical VVI pacing indications. No infections, system failure or impairment of LVEF occurred during almost 4y FU, however an increase in RV pacing demand was observed.