Medtronic reports strong leadless pacemaker data as it races St. Jude to FDA approval

The Micra leadless pacemaker (right) as compared to a traditional pacemaker--Courtesy of Medtronic

Medtronic's ($MDT) leadless pacemaker performed well in a 725-person clinical trial for FDA approval in the U.S., where the bigwig is racing with St. Jude Medical to become the first to sell such a device.

A high 96% of patients implanted with the Micra Transcatheter Pacing System had no major complications at 6 months, and the device was successfully implanted in 99.2% of all patients, Medtronic said at the annual meeting of the American Heart Association in Orlando. The complications included cardiac injuries (1.6%), complications at the groin site (0.7%) and pacing issues (0.3%). There were no dislodgements or systematic infections and a minimal (0.4%) rate of device extraction, repositioning or replacement.

In addition, the Micra met its efficacy endpoint, with 98.3% of patients achieving low and stable pacing capture thresholds at 6 months.

The results are unequivocally positive and keep the company on track for what would be a fast FDA PMA approval in the next fiscal year, beginning May 1, 2016.

"We are extremely pleased with the remarkably successful implant rates and safety profile of the Micra pacemaker, including the absence of device dislodgments. We are especially confident in these results because the trial included patients with serious comorbidities from 19 countries on 5 continents around the world," said Dr. Dwight Reynolds, the trial's principal investigator and chief of the Cardiovascular Section at the University of Oklahoma Health Sciences Center, in a statement. "The Micra TPS not only met its trial endpoints, but also provided a significant reduction in healthcare utilization due to fewer major complications compared to conventional pacing systems, which is particularly important in an era of value-based healthcare."

The Micra is the size of a large vitamin, making it the world's smallest pacemaker, according to Medtronic. Smaller devices are easier to implant, making them desirable. In addition, the company says the Micra can be repositioned and retrieved during implantation, giving heart surgeons greater flexibility during the procedure, and has a CE mark for use during full-body imaging.

As implied by the name, the biggest advantage of the device is that it's leadless. Both Medtronic and St. Jude Medical ($STJ) have suffered lawsuits as a result of failed pacemaker leads (or the electrical wires in traditional pacemakers that typically contact the heart).

An editorial accompanying the trial results in the New England Journal of Medicine said that Micra's functionality and design are "remarkably similar" to St. Jude's leadless Nanostim, which reports the results of its FDA trial in August.

"The short-term performance of the leadless pacemakers (at 6 months), including the persistence of good thresholds and sensing, proved to be excellent in both studies," the editorial concluded (though the Nanostim's major complication rate was a little bit higher at 6.5% and the Micra performed better on the efficacy endpoint as well).

Broadly comparable performance is especially good news for St. Jude Medical because patient deaths from early heart perforation issues plagued the Nanostim's European launch in 2013, leading to a recent relaunch on the continent, where both devices have CE-mark approval.

Still, because both studies are in the early stages, many questions remain. "The rates of dislodgement of leadless devices over time are unknown and are of potential concern. Will the battery life really be more than 10 years, as claimed by the manufacturers? Will these devices be readily extractable to facilitate device replacement when necessary?" the editorial asks.

While leadless pacemakers are off to a good start in terms of safety, technological limitations will restrict their use to single-chamber ventricular pacing, "a procedure generally reserved for patients with atrial fibrillation and bradycardia or in patients thought to need infrequent pacing," according to the editorial, which adds that the devices will have "limited usefulness" in the majority of patients in need of a pacemaker.

St. Jude has said it is working on a dual-chambered leadless pacemaker, which would be a pharma-style blockbuster if the engineering challenges are overcome.

Boston Scientific ($BSX) is entering the race too. It hopes to offer a leadless pacemaker that can treat a broad range of heart failure patients by pairing the potential device with its S-ICD.

The fast-selling S-ICD has shown the potential of cardiology products that eliminate or lessen the use of leads, albeit in the related but distinct market for implantable defibrillators. Sales of the S-ICD are more than $100 million per quarter. Its leads do not come into contact with the heart.

- read the release
- here's the editorial in the NEJM | here's the study

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