A new device implanted in the heart proved in a large clinical study to be a potential alternative to a standard blood thinner for helping patients with irregular heart beats prevent stroke, researchers said on Saturday.

The cage-like device, known as the Watchman, reduced the risk of stroke and cardiovascular death by 32 percent compared to warfarin, a widely used blood thinner that is notoriously difficult to manage and carries a high bleeding risk.

The Watchman, made by privately held Atritech Inc, had twice as many procedure-related complications - most of them related to its implantation - but researchers concluded it is an effective alternative to warfarin.

“The take-home message is that although there are complications associated with implantation of the device, patients can avoid the need for chronic warfarin therapy, with all its attendant risks,” said Dr. David Holmes, professor of medicine at the Mayo Graduate School of Medicine in Minnesota, who presented the PROTECT AF study at the American College of Cardiology scientific meeting in Orlando.

Atrial fibrillation is a common heart rhythm disorder that creates blood clots and increases the risk of stroke. The disorder is found in about 2.2 million Americans and about 15 percent of strokes occur in people with atrial fibrillation, according to the American Heart Association.

Several cardiologists at the conference expressed excitement about an alternative to warfarin, also known by the trade name Coumadin, but were wary about the safety of the Watchman and the challenges of the implementation procedure.

“It sure is intriguing to at least show that we can probably find some patients that we can get off of Coumadin,” said Dr. David Cox, a cardiologist in Allentown, Pennsylvania. “I think the big question mark is the safety of the device.”

The Watchman is an expandable cage designed to keep harmful blood clots that form in the left atrial appendage of the heart from entering the blood stream and potentially causing a stroke.

The device - which ranges from as large as a penny to a half-dollar depending on the size of the appendage - is guided to the heart through a catheter inserted through a vein in the upper leg.

It is placed just behind or at the opening of the left atrial appendage, isolating the appendage where the vast majority of clots are formed, according to Atritech.

In the 707-patient PROTECT AF study, which was sponsored by Atritech, 463 atrial fibrillation patients were randomly assigned to the Watchman and 244 patients to warfarin.

The combined rate of stroke and cardiovascular death - the primary effectiveness measure - was 3.4 per 100 patient years in the device group, compared to five per 100 patient years in the warfarin group. That amounted to a 32 percent risk reduction.

The device showed superiority in reducing the risk of Hemorrhagic stroke, which involves bleeding in the brain.

But more procedure-related complications were seen with the Watchman - 8.7 per 100 patient years, compared with 4.2 for warfarin. Safety events, including fluid build-up in the heart, decreased over time.

Atrial fibrillation patients commonly take warfarin to prevent clots from forming and causing strokes. But warfarin comes with a significant bleeding risk and its administration is cumbersome because patients must be closely monitored when on the drug.

JP Morgan analyst Mike Weinstein said there was a “learning curve” for the procedure but that the data was strong and the device has promise.

Atritech filed a U.S. application to the Food and Drug Administration in August seeking marketing approval for the Watchman, which included the results of the PROTECT AF trial. An FDA advisory panel will review the product on April 23.

Stock analysts have speculated that if the PROTECT AF trial is successful, Minnesota-based Atritech would be an attractive acquisition target for larger medical technology companies.

Atritech on Friday announced it received $30 million in financing. The funding will allow the 40-person company to launch the product in May in Europe, where the device is already approved, and commercialize the device by itself in the United States, according to Chief Executive Jim Bullock.

By Lewis Krauskopf
ORLANDO, Fla. (Reuters)