Leadless pacemaker shows promising results at 1 year

SAN FRANCISCO — The Nanostim leadless pacemaker continued to show safety and efficacy at 1 year, according to findings from the LEADLESS study presented at the Heart Rhythm Society Annual Scientific Sessions.

The Nanostim (St. Jude Medical), a self-contained, single-chamber leadless cardiac pacemaker implanted via a catheter-based procedure, was designed with reducing complications, which are often the culprit of the lead, in mind, Vivek Y. Reddy, MD, director of the cardiac arrhythmia service at Mount Sinai Hospital, said at a press conference.

“Pacemakers work very well, but we also know that leads do have complications, such as surgical issues such as infection, and lead-related complications such as fracture,” Reddy said. “Removal of leads can also be a very difficult thing.”

Vivek Y. Reddy

Three-month data for the LEADLESS pilot study of 33 patients were published in March. Reddy reported 1-year data here. The patients were implanted with the device between December 2012 and April 2013.

According to Reddy, the mean pacing thresholds (at 0.4 ms) were 0.8 V at implant, 0.46 V at 3 months, 0.4 V at 9 months and 0.43 V at 1 year; R-wave sensing was 8.26 mV at implant, 10.65 mV at 3 months, 10.64 mV at 6 months and 10.32 mV at 1 year; impedance was 773 ohm at implant, 627 ohm at 3 months, 625 ohm at 6 months and 627 ohm at 1 year; and battery voltage was 3.17 V at implant, 3.21 V at 3 months, 3.23 V at 6 months and 3.29 V at 1 year.

No further complications

The 90-day data had demonstrated an implant success rate of 97% and a complication-free rate of 94%. There were no further complications between 90 days and 1 year, Reddy said. This included no evidence of device migration or dislodgement, ventricular arrhythmias, infection, device malfunction or early battery depletion.

“It behaved just like we expected,” Reddy said. “It continues to sense and pace appropriately, the battery voltage is as we expected, there are no additional complications, and fundamentally, the device seems to work.”

The Nanostim received a CE Mark in February and investigators have begun enrolling patients in LEADLESS II, a pivotal trial of approximately 670 patients that will serve as the basis for an FDA approval decision.

Implantation challenges

The one failed implant in LEADLESS occurred because of cardiac perforation during device implantation, and more perforations have been reported in Europe since the device was approved there, Reddy noted.

“What we need to understand is how frequently this will happen,” he said. “We know that there are complications related to implantation, even with traditional leads. We also know that with any new technology, there is going to be some amount of complications related to the procedure. As one could anticipate, there have been such complications. Is it an initial learning curve issue, which we sort of expect, or is it something that can be sustained long term? At this point, we don’t believe it’s going to be the latter, but only time will tell.” – by Erik Swain

For more information:

Reddy VY. Abstract LB02-01. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 7-10, 2014; San Francisco.

Disclosure: The study was funded by Nanostim Inc., which is owned by St. Jude Medical. Reddy is a consultant to and advisory board member for St. Jude Medical and in 2013 received one-time financial compensation from St. Jude Medical in the form of an option buyout relating to the company’s acquisition of Nanostim.