Medtronic PLC scored an industry first this month with U.S. approval to start selling its leadless pacemaker, Micra, which represents the first entry in what may become a new class of slender, minimally invasive pacemakers that rest entirely inside the heart.
But if these new pacemakers are going to revolutionize the business of keeping hearts in rhythm, they will have to be perceived as safe.
That's why Medtronic has developed a rigorous training program for doctors who want to implant its vitamin-pill-sized device. The Minnesota-designed Micra attaches to the inner heart wall directly, avoiding the need for insulated wires called leads to deliver the pacemaker's electric pulses. Leads have been called the "Achilles' heel" of pacemakers because they can wear out and create infection risk.
Leadless pacers, implanted inside the heart's right ventricle, are expected to grow into a $700 million global market in coming years, analysts estimate. That tally may grow exponentially as the devices grow in complexity to pace two or even three chambers of the heart, instead of just one. Less than a quarter of pacemakers sold today are so-called single-chamber devices.
This month, Medtronic's single-chamber Micra became the first leadless pacemaker to get U.S. Food and Drug Administration approval, following a global clinical trial that found a consistent safety record and a paucity of bad outcomes.
Company officials say those results likely flow, at least in part, from a multistage training program used to familiarize doctors in the study with how to properly implant a new type of medical device. Medtronic is now preparing to roll out the same training system across the country.
"It was a pretty robust training. And I think that is part of the reason" why none of the 725 Micra devices implanted during the trial became dislodged in the heart, said Dr. Robert Kowal, a Dallas electrophysiologist who put in about 15 of the devices during the company-sponsored, nonrandomized clinical trial.
Kowal and other new implanters received on-site training using a cadaver and implanting in animals. Medtronic officials said training for most new implanters may include simulators, video explanations and other methods, either at a Medtronic facility or at the hospital. The initial implanter at a hospital trains others by letting them first observe cases, then "scrubbing in" with the experienced doctor for five cases, and finally doing the procedure themselves under observation.
Medtronic's crosstown pacemaker rival, St. Jude Medical, has developed a similar mandatory training regimen for its leadless pacemaker, the Nanostim. The training is only available to doctors affiliated with a health care organization that has the resources to support a leadless pacemaker program, including high-resolution continuous X-ray systems and access to emergency facilities to manage potential complications.
Nanostim is not yet for sale commercially in the United States, but executives expect to get approval sometime in the second half of this year.
St. Jude received approval for the Nanostim in Europe in 2013 — two years before the Micra did. But studies of the Nanostim were halted after early reports of dislodgements and other bad outcomes.
St. Jude has since revised its training program and its selection criteria for potential patients. A St. Jude executive told an FDA advisory panel in February that adverse events like dislodgements and heart-tissue perforation decreased considerably after those changes.
Dr. Kim Selzman, a Utah cardiac electrophysiologist, told the FDA advisory panel members in February that a "learning curve" is often seen with new devices and technology.
"St. Jude did conduct a learning-curve analysis and reported that after 10 implants, the device-related serious adverse events were almost reduced by half. And so it does appear that, similar to other new technologies, there might be a learning curve with the implant procedure for leadless pacemakers. This raises the issue that training may be beneficial and valuable to implanters who are new to this technology," Selzman told the panel.
The physicians on the FDA panel recommended a robust training program for doctors implanting leadless pacemakers. When the FDA approved the Micra on April 6, it required Medtronic to include the specific training or experience that doctors need on the device label.
The FDA panel urged for training around two issues in particular, both of which involved the novel way that leadless pacemakers are deployed inside the body.
A traditional pacemaker is placed in a "pocket" of skin near the shoulder, and connects to leads strung through major blood vessels to deliver electric pulses to the heart. In contrast, leadless pacemakers fit in a flexible tube the size of a large drinking straw, which is advanced into the heart from a small incision in the leg. Tiny bits of metal on the end of the pacemaker hook or screw into the heart tissue.
The FDA panel noted that training was needed because leadless pacemakers' complication risks in the clinical trials seemed to increase with the number of times that the devices had to be repositioned in the heart.
Training was also needed, the panel said, because the tube that is fed through the blood vessels is wider and tougher to maneuver than thinner catheters commonly used in other minimally invasive procedures.
Business executive Ron Weeks said the procedure to implant his leadless pacemaker could not have gone more smoothly.
Weeks, 72, of Eden Prairie, said he had a Micra put in at Abbott Northwestern Hospital as part of a clinical study through the Minneapolis Heart Institute Foundation about six months ago. He said he sought out the device because he only needed a single-chamber pacemaker, and the idea of minimally invasive procedure with a short recovery time and no scars on the chest appealed to him.
"They put it in in the morning. I had a normal lunch. In the hospital, they ran tests and things like that, and I left the next morning," he said. "It was an easy procedure."
Joe Carlson • 612-673-4779