Wire-Free Pacemaker Shows Promise

Conventional cardiac pacemakers are implanted in nearly 1 million people worldwide every year. According to research presented at the European College of Cardiology 2015 Congress in London, UK, about one patient in 10 will have an adverse event related to the device.

Vivek Reddy, MD, of the Icahn School of Medicine at Mount Sinai in New York City, and colleagues reported that a leadless device (Nanostim/St. Jude Medical) implanted non-surgically via a catheter through the femoral vein had a better safety record, with 6.7% of patients experiencing serious adverse events.

The study was discussed in an online article in The New England Journal of Medicine.

In 300 patients who completed a six-month follow-up in June 2015, cardiac perforation, device dislodgement, and elevated pacing thresholds necessitating device retrieval and replacement were reported in 1.3%, 1.7%, and 1.3% of patients, respectively. Vascular complications were reported in 1.3% of the patients.

In the full cohort of 526 patients, “the mean sensing and pacing threshold values improved significantly over time from the values observed at the time of pacemaker implantation,” the team reported. The adverse event rate in the full cohort was 6.5%.

The rates of adverse events declined as operators inserting them grew more experienced. That rate was 6.8% for the initial 10 cases, and 3.6% for subsequent implants.

A rival device made by Medtronic, marketed as Micra, had a higher rate of adverse events, 18.6%, the authors noted.

There are limitations on both the study and the market for Nanostim, the researchers said. “Currently the leadless cardiac pacemaker can serve as only a single-chamber ventricular pacemaker, which accounts for a minority of implanted pacemakers in the US,” they wrote.

The study’s six-month follow-up limits “understanding of long-term efficacy and pacemaker-related complications, particularly in comparison with conventional pacemaker systems,” they noted.

Further, the device cannot provide electrographic data, a refinement that would be necessary for the wireless pacemakers to replace conventional devices.