Leadless cardiac pacemaker draws plaudits



DENVER – A first-in-man study has demonstrated that a novel leadless cardiac pacemaker is easy to implant percutaneously in the right ventricle, is readily retrievable when required, and performs like a conventional single-chamber permanent VVIR pacemaker.

"This is a relatively small feasibility study, but I think this new leadless pacemaker has the possibility of effecting a real paradigm shift in how we think about pacing. We’re going to be able to eliminate what has been the weak link in the pacemaker system: the lead," Dr. Vivek Reddy predicted in presenting the results of the LEADLESS study at the annual meeting of the Heart Rhythm Society.

More than 4.4 million people worldwide have a cardiac pacemaker. More than 65,000 of them develop chronic problems related to the pacemaker leads, including lead dislodgement, infection, lead failure, and hematoma. In one major study, the overall complication rate over the life of conventional pacemakers was close to 8%.

Dr. Vivek Reddy

These complications come at considerable cost. A lead infection can easily add $50,000 to the cost of care, a lead revision $16,000, noted Dr. Reddy of Mount Sinai School of Medicine, New York.

The leadless pacemaker is about the size of a triple-A battery. Vascular access for its placement is gained in standard fashion through the femoral vein using a steerable 18F catheter. The device is typically placed in the right ventricular apex and fixed in place by a single turn of an attached helix. The single-chamber pacemaker uses low-power electronics and has an estimated battery life of 8-17 years, depending upon how much of the time it’s actively pacing. The pacemaker senses right ventricular blood temperature, using it as a guide to boost pacing rate in response to increased metabolic demand.

In the LEADLESS study, 32 of 33 patients at three European centers underwent successful pacemaker implantation. The procedure took roughly 30 minutes initially, but times came down with greater operator experience. The most common indication for a permanent single-chamber pacemaker among study participants was chronic atrial fibrillation with second- or third-degree atrioventricular heart block.

The pacemaker is designed so the interventionalist can quickly determine if the device has been placed in an optimal location; if not, it can be repositioned during the same procedure before being finally locked into place. Twenty-three of the 32 patients did not require any device repositioning.

Dr. Michael R. Gold

During 3 months of study follow-up, two patients required device retrieval. In one, the leadless pacemaker had migrated through an open patent foramen ovale into the left ventricle. The other patient developed indications warranting an implantable cardioverter-defibrillator. Device retrieval was a straightforward matter and took 6 and 13 minutes, respectively, using a basket catheter.

The one serious adverse event in the study involved a patient who experienced cardiac perforation and tamponade during pacemaker implantation. Five days after an uncomplicated surgical repair, the patient had a large right-sided stroke and died.

Dr. Reddy said the leadless pacemaker will be commercialized in Europe later this year. Planning is underway for a large, multicenter U.S. trial that will probably start next year. And Nanostim, the company developing the device, is also working on a leadless atrial pacemaker that will be able to communicate with the right ventricular pacemaker in order to provide multichamber cardiac pacing.

Dr. Reddy’s presentation met with an enthusiastic response.

"This is fascinating, incredible technology," declared Dr. Andrea M. Russo of Cooper University Health Care in Camden, N.J.

"The idea of being able to put a pacemaker into someone without having leads and without having a device under the skin is probably the next phase of what we’d hope to do with cardiac pacing therapy," Dr. Michael R. Gold observed.

"I think most of us, if we were to make predictions about what’s in store 10 years from now, we’d be hoping that we’d no longer use leads, which are the component that fails most frequently in any device. If we can get rid of the leads, put these little pacemakers anywhere we want in the heart, and get them to cross-talk and communicate with each other, that’s very exciting," said Dr. Gold, professor of medicine, chief of cardiology, and medical director of the heart and vascular center at the Medical University of South Carolina, Charleston.

The LEADLESS study was funded by Nanostim. Dr. Reddy has received research grant support from and is a consultant to the company.

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