Leadless Micra Pacemaker Implantations in Lithuania: Population and Indications

Introduction Leadless pacemakers (LP) represent an established alternative to traditional transvenous permanent pacemakers (TV-PPM) in the management of brady-arrhythmias [1]. The primary indication for LP implantation over conventional pacemaker is due to a higher risk of device-related infections. The procedure has a high success rate and a low risk of major complications [2]. Since 2018, Kaunas Clinics has been the only medical institution in Lithuania performing this procedure. However, there is no data in the scientific literature regarding the population and indications for which LP implantation was performed. Aim To assess the demographics and clinical data for LP implantation in the Lithuanian population over the past seven years. Methods A retrospective analysis was conducted using the computerized medical data of all patients who received LP implantation at the Hospital of the Lithuanian University of Health Sciences (LUHS) Kaunas Clinics between January 1, 2018, and December 22, 2024. The study was approved by the Bioethics Centre of LUHS (2024-BEC2-1217). Results The research involved 18 individuals who received the Medtronic Micra™ model MC1VR01 LP. There were 10 females (55.6%) and 8 males (44.4%). The number of LP implantations per year was: 3 – 2018, 2 – 2019, 1 – 2020, 4 – 2021, 2 – 2022, 6 – 2023, and 0 – 2024. Eleven patients (61.1%) – 6 females and 5 males – are alive, with a median (IQR) age of 80 years (73–90). Seven patients (38.9%) – 4 females and 3 males – died for reasons unrelated to LP implantation (1–4 years after implantation), with a median (IQR) age of 86 years (80–92). The median (IQR) age at the time of LP implantation was 80.5 years (72.5–80.5). The median (IQR) BMI was 26.8 kg/m2 (23.2–30.9). The indications for pacemaker implantation were as follows: 50.0% for bradyarrhythmia with atrial fibrillation (AF), 38.9% for atrioventricular block, and 11.1% for sinus node dysfunction. The indications for LP were as follows: 33.3% for left- and right-sided TV-PPM pocket infection and explantation, 33.3% for left-sided, 27.8% as the first choice, and 5.6% for left- and right-sided subclavian vein occlusion. The median (IQR) procedural duration was 97.5 min (71.2–120.0). Early ventricular pacing threshold values were 0.65 V (0.52–0.80) at 0.24 ms, with an R wave on 12.8 mV (8.2–16.4), device longevity > 8 years. Conclusions Since the introduction of LP implantation in Lithuania, 18 devices have been implanted. The median age at Micra LP implantation was 80.5 years, while the median age at death was 86 years. The primary indication for Micra LP implantation was TV-PPM pocket infection, pacing system infection, or an increased risk of bacterial complications, while the main indication for stimulation was bradyarrhythmia with AF.