|St. Jude's Nanostim leadless pacemaker--Courtesy of St. Jude Medical|
Leadless pacemakers from Medtronic ($MDT) and St. Jude Medical ($STJ) performed well in clinical trials, setting the stage for an exciting race for FDA approval between the two bigwigs. In a sign that the finish line is getting closer, the FDA is convening the experts on its circulatory system devices advisory panel to discuss optimal regulation of the devices.
Both companies will make presentations during the meeting. During the 300-patient trial of Medtronic's leadless Micra, the implantation success rate was 99%, with 15% of procedures requiring repositioning and one procedure-related death occurring. Meanwhile, St. Jude's leadless Nanostim had an implantation success rate of 95%, with 30% requiring repositioning and two procedures resulting in a patient death, the FDA said. Both devices have already obtained CE mark approval in Europe, where commercialization is in its early stages.
The questions for the panel members will elicit their thoughts on adverse events, patient selection, and physician training. The usual questions about labeling and instruction for use will also be up for discussion.
In addition, the panelists will be asked about how to best collect data in the postapproval setting. Consideration of postmarket issues at such an early premarket stage provides further evidence that the agency is serious about its shift toward increased emphasis on monitoring and data-gathering following approval.
It's particularly important in the case of leadless pacemakers because, as the agency writes, "the long term (5-10 years) safety profile of the leadless devices is currently unknown." One area of concern is their battery life, which the FDA estimates to be 6 to 12 years.
In terms of short-term complications, traditional pacemakers are a good deal safer than the leadless ones when it comes to traumatic perforations (which occur in 1.6% of leadless implantations) because they are significantly smaller. Also, leadless ones do not suffer from so-called pocket complications because they do not have any leads (or conductive wires). These occur following 4.75% of traditional pacemaker implantations, the FDA says.
|The Micra leadless pacemaker (right) as compared to a traditional pacemaker--Courtesy of Medtronic|
Perhaps most importantly, leadless pacemakers avoid other problems related to leads, such as lead fractures and insulation problems, which have plagued the wires in the past.
St. Jude agreed last year to pay as much as $14.25 million to settle about 950 claims related to its Riata defibrillator leads. The wires used to shock a heart that is beating abnormally degraded in as few as four years and were pulled from the market in 2010. Meanwhile, Medtronic's Fidelis leads were hit with four Class I recalls in 2007 and were associated with a handful of patient deaths.
The quality of leads has improved over the years, but St. Jude's recent warning that 447 of its Optisure defibrillator leads may have a manufacturing defect that could have introduced damage to the wires' insulation demonstrates the inherent risks.
Still, due to improved lead safety, the biggest advantage of leadless pacemakers could turn out to be their small size, which improves the ease of implantation.
Both investigational pacemakers are single-chambered devices, which limits their applicability to many heart failure patients. A dual-chambered leadless pacemaker has the potential to be a true blockbuster but presents many engineering challenges that have yet to be overcome.