Real world performance of ventricular leadless pacemaker in a cohort with smaller body size

Ventricular leadless pacemaker was shown to be safe in investigational device exemption (IDE) trials and post approval registries. However, these studies were company sponsored and maybe limited by selection bias because the sickest patients often could not consent for enrolment. Implanting it in older patients with small body size may also be more challenging.

We evaluated the safety of ventricular leadless pacemaker implantation in a cohort consecutive patients.

This is a investigator initiated retrospective cohort study of consecutive patients implanted with Micra or Aveir ventricular leadless pacemaker in a tertiary referral centre in Hong Kong from 2015 to 2025. Patient's demographic, implant characteristics and complication data were gathered from local electronic health record. The territory-wide health record database of Hong Kong Hospital Authority was accessed to ensure data completeness and no loss to follow up. Student t tests were used to compare the demographics of our cohort with existing registries.

857 consecutive implants were included for analysis (626 Micra VR or AV and 231 Aveir VR). The mean age at implant was 79.7 ± 8.7. The cohort was older than that of Micra IDE study (75.9 ± 10.9, p<0.001), Micra post approval registry (75.6 ± 13.5, p<0.001) and Aveir leadless II IDE trial (75.6 ± 11.3, p<0.001). The body mass index was 23.8 ± 4.22kg/m², which was lower than that in Micra IDE trial (27.6 ± 5.3, p<0.001). BMI was not reported in Aveir leadless II trial or Micra post approval registry. Co-morbidities were common in the cohort (Table 1). After a median follow up of 47.7 (IQR 18.9 - 74.9) months, major complications occurred in 35 patients (4.1%). There was no procedure related death, nor complications resulting in open heart rescue (Table 2). Pericardial effusion occurred in 6 (0.72%) cases (5 managed with percutaneous drainage, 1 conservative treatment). Pacemaker system revision was performed in 12 cases (1.4%), of which 6 cases (0.7%) were due to pacing related cardiomyopathy.

In this real world cohort with older age and smaller body size then existing world wide registries, ventricular leadless pacemaker was demonstrated to be safe after a median follow up of 4 years.Table 1Table 2