Effects of different pulse duration programming on battery longevity in a leadless pacemaker with active fixation

Leadless pacemakers (LCP) have been used for around 10 years and, according to the current ESC guideline, are an alternative to the classic transvenous pacemaker in selected patients without venous access or with an increased risk of pocket infection. The single-chamber devices implanted intracardially via V. femoralis are indicated for bradyarrhythmia due to permanent atrial fibrillation or to prevent syncope. The AVEIR™ is currently the only LCP with active myocardial fixation, the possibility of intracardiac mapping before final fixation and also for long-term extraction. Compared to the Micra™, the AVEIR™ is characterized by significantly longer battery life and the option of upgrading to a dual-chamber system. 

 

Since licensing in Europe in September 2023 we have implanted 43 AVEIR™ VR in our center. These were analyzed with regard to values measured peri- and postinterventionally as well as in follow-up. In particular, we investigated the development of the stimulation thresholds of the LCP and possible influences of the programming on the battery life, depending on the stimulation rate.

 

We included 43 patients with bradycardic atrial fibrillation (mean age: 81 yr). The median total operating time was 96 min (range 53-165)  and the median implantation time, defined as the time between correct catheter lock position and pacemaker release, was 19 min (range 9-41). The basal heart rate was set at 50-65 bpm, resulting in a ventricular pacing rate between 1% (patient with planned AVN ablation) and 99 % (mean 28 %).

The patients were divided into 3 cohorts based on the rate of ventricular stimulation (VP). Across all cohorts, the stimulation threshold improved steadily after implantation from initial median 0.75 V at 0.2 and 0.4 ms to 0.5 V at 0.2 and 0.4 ms at the 3-month follow-up. A one-year follow-up is already available for the first patients, which shows a trend towards further improvement of the stimulus threshold. The analysis of the individual cohorts with regard to the predicted battery life depending on stimulus threshold and impulse duration showed for patients with VP <30 % a median of 21.1 ± 1.64 yr at a impulse duration of 0.2 ms and 22 yr at a impulse duration of 0.4 ms. For the cohort with a VP of 30-70 %, the median was 19.4 ± 1.56 yr with a impulse duration of 0.2 ms and 18 ± 2.86 yr with a impulse duration of 0.4 ms. Patients with a high VP (>70 %) showed a median of 18.68 ± 3.05 yr with a impulse duration of 0.2 ms and 18 ± 4.87 yr with a impulse duration of 0.4 ms.

 

The battery life of a pacemaker depends on the programming of the impulse amplitude and impulse duration. For conventional pacemakers the optimal impulse duration is 0,4 ms. Based on our results we can show that shortening the impulse duration in a leadless pacemaker with active fixation prolongs the battery life – depending on the pacing level. This significant effect may be explained by the design of the pacemaker. To clarify this question further investigations are necessary comparing the leadless and conventional pacemaker. 

According to the current guidelines, we consider the leadless pacemaker to be indicated for permanent bradyarrhythmia and for patients with stenosis of superior veins. Another advantage of the AVEIR™ VR is the upgrade option to a dual-chamber system AVEIR™ DR, which was first implanted in Germany in August 2024 in our center.