LEADLESS II: Safety and Efficacy of a Leadless Pacemaker
The leadless cardiac pacemaker may be capable of providing effective pacemaker function in a varied group of patients needing long-term pacing therapy, according to results of the LEADLESS II Trial presented Aug. 30 at ESC Congress 2015 in London, and simultaneously published in the New England Journal of Medicine.
The multicenter study enrolled 526 patients requiring permanent single-chamber ventricular pacing. The primary efficacy end point was both an acceptable pacing threshold and an acceptable sensing amplitude through six months. The primary safety end point was freedom from device-related serious adverse events through six months.
Overall results showed the leadless pacemaker met prespecified pacing and sensing requirements in the large majority of patients. The active-fixation leadless pacemakers were successfully implanted in 504 patients (95.8 percent). The intention-to-treat primary efficacy endpoint was met in 270 of the 300 patients in the primary cohort (90 percent) and the primary safety endpoint was met in 280 of 300 patients (93.3 percent). Device-related serious adverse events were observed in roughly one in 15 patients at six months, including device dislodgement with percutaneous retrieval (1.7 percent), cardiac perforation (1.3 percent) and pacing-threshold elevation requiring percutaneous retrieval and device replacement (1.3 percent). Vascular complications occurred in 1.3 percent of patients.
Investigators noted that the study was limited by the observational design that did not directly compare the leadless cardiac pacemaker with conventional pacemakers. Additionally, the six-month follow-up period limited understanding of long-term efficacy and pacemaker-related complications.
"Leadless cardiac pacemakers create a paradigm shift in how we are going to look at pacemaker therapy over the coming years," said Jagmeet P. Singh, MD, DPhil, deputy editor of JACC: Clinical Electrophysiology. "While leadless cardiac pacemakers are only available as single-chamber pacemakers at this juncture, there will be opportunities for dual- as well as three-chamber approaches in the future. Hopefully this technology will continue to evolve and incorporate the device diagnostic and remote monitoring capabilities that are present in currently available pacemakers."
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