Real-world long-term battery longevity of leadless pacemakers
Authors: Breeman K T N , Dijkshoorn L A , Beurskens N E G , Wilde A A M , Tjong F V Y , Knops R E 
Published: October 2022

Abstract

Background
Leadless pacemakers (LPs) have proven safe on the mid-term. Long-term safety will largely depend on the need for replacements with a concomitant risk of complications. As replacements are mainly due to battery depletion, battery longevity is, in essence, an important determinant of long-term safety. Mean battery longevity of the most often implanted LP (Micra VR) predicted by the manufacturer is 12 years, but mid- and long-term data is lacking.

Purpose
We sought to determine the long-term battery longevity of this LP in a real-world cohort.

Methods
Consecutive patients with an LP implantation at our tertiary hospital from January 2014 to September 2021 were included in a prospective cohort. Baseline characteristics and electrical parameters during all yearly follow-up visits were assessed.

Results
105 patients (73 [70%] male, age at implantation 80±9 years) were included. Pacing indications were atrial fibrillation with slow conduction (34 [32%]), third degree AV block (35 [33%]), incomplete AV block (12 [11%]), sinus node disease (23 [22%]) and unexplained syncope (1 [1%]). At implantation, pacing threshold, impedance and R-wave amplitude were 0.76±0.64V at 0.24ms, 790±220Ω and 11.1±4.9mV, respectively, lower rate was programmed at 50–60/min in 88 (84%), &lt;50/min in 8 (7.6%) and &gt;60/min in 9 (8.6%) and rate-responsive pacing was programmed on in 51 (49%). Median follow-up was 25 months (range 2–88 months). Pacing percentage was 46% (IQR 12–98%) at year 0; 64% (10–99%) at year 5 and 91% (56–100%) at year 7.
No battery failures were seen during follow-up. At 3 years, expected battery longevity was &gt;8 years (maximum value) in nearly all patients (49/50 [98%]) and at 5 years in the majority (16/18 [89%]) of patients; at 7 years, expected battery longevity ranged from 4.1 to &gt;8 years (Figure). This implies an expected battery longevity of &gt;13 years in the majority of patients. In two subjects, expected battery longevity was below the maximum value within 5 years after implantation. In the first, latest follow-up visit was after 3 years and expected battery longevity was 3.0 years. An increase in pacing percentage of +70 percent points was seen during follow-up and there was a relatively high pacing capture threshold (1.5V@0.4ms). In the second, the latest follow-up visit was at 6 years, and expected battery longevity was 1.9 years. This was caused by a large increase in pacing percentage (+80 percentage points) and lower rate of 70/min; pacing threshold was 0.5V@0.24ms. We did not see clear overall differences in expected battery longevity at 5 years, when the patients were stratified per quartile pacing percentage. Of 34 deaths during follow-up, 31 (91%) had expected battery longevity &gt;8 years at the last follow-up visit.

Conclusions
These long-term real-world data suggest that the battery longevity of the Micra LP will exceed the expected battery longevity. Data from larger registries is necessary to confirm these results.

Funding Acknowledgement
Type of funding sources: None.