Efficacy and safety of leadless ventricular pacemaker: a single-center retrospective observational study

The Micra leadless pacemaker (MLP) has been demonstrated to be safe and effective as a substitute for conventional transvenous ventricular pacemakers (TVP). However, its application in the general population is still restricted. The aim of this retrospective study was to assess the safety and efficacy of MLP.

Clinical data and device parameters were gathered on every patient receiving MLP implantation between 1 January 2019 and 31 December 2023, in the First Affiliated Hospital of Soochow University. The efficacy of MLP on the primary composite endpoint, atrioventricular (AV) synchrony, hospitalization, and post-implantation quality of life was assessed. Safety outcomes included implantation procedural characteristics, acute and chronic complications, and stability of pacing parameters. Meanwhile, we compared pacing parameters, AV synchrony, and improvement of life quality between patients who had been implanted with the MicraTM VR (Medtronic Micra™ MC1VR01) and Micra™ AV (Medtronic Micra™ MC1AVR1). Multivariate linear regression models were used to unearth potential predictors of echocardiography or electrocardiogram (ECG) parameters on pacing parameters.

A total of 94 patients were included, and implantation was successful in all of the cases. A single patient experienced effusion hours after the implantation, indicating a low rate of both acute and chronic complications. In patients with complete AV block (AVB), Micra AV increased AV synchrony from 23.2%±6.3% to 80.8%±5.7%. After 28 days of implantation, the patients' Minnesota Living with Heart Failure Questionnaire (MLHFQ) score decreased from 27.1±18.6 to 20.0±17.6, and none of them required hospital readmission. Left ventricular end-diastolic diameter (LVEDD, 50.0±6.7 cm), left ventricular end-systolic diameter (LVESD, 32.6±3.9 cm), and ECG R wave in lead V5 (RV5, 1.3±0.6 mV) can be employed for the prediction of pacemaker threshold [0.50 (0.38-0.67) mV], sensing voltage (10.1±4.7 mV), and impedance (785.9±226.4 Ohm) correspondingly.

Despite being a small, single-center, retrospective study, our study provided data for assessing the safety and efficacy of MLP. Clinicians and patients can make well-informed therapy decisions by being aware of its benefits and forecasting pacing parameters.