Minimally invasive heart-valve replacement technology has allowed thousands of previously inoperable patients to get their hearts fixed. But some of those patients go on to develop strokes within days of the procedure.
On Monday the Food and Drug Administration cleared the Claret Sentinel Cerebral Protection System, the first medical device designed to catch potentially dangerous particles that break loose from the aortic valve following a "transcatheter" aortic valve procedure before the tiny bits can travel to the brain and cause harm.
Minnesota-run Medtronic is one of the key makers of the new minimally invasive transcatheter heart valves, along with California's Edwards Lifesciences. However, it was a third company called Claret Medical that received FDA clearance on Monday to sell a special filtering device intended to improve the safety of Medtronic's and Edwards' popular new heart valves.
The FDA's decision was all the more notable because Claret's key clinical study technically failed to accomplish its goal — but the device was approved anyway.
"It's fair to say that debris going to the brain can't be a good thing for anybody. … We capture debris in 99 percent of cases," said James Hallums, general manager and senior vice president with Claret. "This debris creates ischemic lesions; it creates cell death in the brain. Until someone proves those are a positive thing, then I guess it makes sense to assume that every patient would potentially benefit as we move forward."
Severe aortic stenosis happens when the main valve that pushes fresh blood to the organs becomes damaged or calcified. Transcatheter aortic valves, named for the thin tube called a catheter that the doctor uses to push the new valve into place, are implanted directly on top of the old diseased valve. But the process of squishing the old valve in place and rubbing against the aortic arch during the procedure can release gunk, calcium and chunks of tissue into the bloodstream.
During an FDA review meeting for the device in February, physicians displayed pictures of tiny bits of arterial and heart tissue, grains of calcium and "foreign material" that were captured by the Sentinel's fine mesh filters.
"Strokes associated with TAVR procedures are known to occur and reducing these events is a particular area of interest," FDA experts wrote in an executive summary for the February meeting, using the abbreviation for transcatheter aortic valve replacement.
Previous studies pegged the stroke rate after minimally invasive aortic valve implants at between 2 and 10 percent.
Hallums said Americans are getting about 30,000 TAVR procedures each year, and that figure may grow as the technology is accepted for less-risky patients.
However, more recent versions of the valves have shown lower rates of stroke than were seen in early studies. And since the Sentinel did not show a statistically significant decrease in the formation of blockages in specific areas of the brain in its pivotal trial, it's not clear that insurers are going to agree to pay for the device soon, said Sean Messenger, a manager with health care research and analytics firm Decision Resources Group.
"Given that the clinical benefit is unclear, reimbursement might be hard to come by. If Claret can get [Medicare] reimbursement for Sentinel, then they will become much more attractive and I would be surprised if they remained independent for long," Messenger said when asked whether the FDA approval would cause Claret to be quickly acquired.
Hallums said that right now, the company is focused on commercializing its device. It has not accepted funding from other major device companies, he said. Although he declined to release the price of the device, a news release Monday noted that the company is working with Medicare to see if the agency will pay more for a TAVR procedure that uses a Sentinel device, known as a "technology add-on payment."
Medtronic, for its part, agreed that reducing the risk of stroke during and immediately after a transcatheter aortic valve replacement is an important goal.
"We are pleased to have demonstrated exceptionally low rates of clinical stroke for patients treated with the CoreValve platforms in large, randomized clinical trials," the company said in a statement, referencing its CoreValve line of TAVR devices.