A device designed to keep dangerous blood clots from entering a patient's blood stream and possibly causing a stroke, may soon provide atrial fibrillation (AF) patients an alternative to taking problematic blood-thinning drugs.

Atritech (Plymouth, Minnesota) has filed a pre-market approval (PMA) application with FDA for its Watchman Left Atrial Appendage (LAA) closure device. The company said the PMA contains the results of its PROTECT AF trial, which evaluated the Watchman LAA closure device vs. the current standard of care, the drug warfarin, in patients with non-valvular AF at risk of stroke.

"Patients with atrial fibrillation have six times greater risk of stroke and that's really because of the physics of Afib, the upper chambers beat irregularly and very rapidly and blood tends to pool and clot and the clot goes either to the brain or the vascular system," Jim Bullock, president/CEO of Atritech, told Medical Device Daily.

Usually, AF patients are prescribed warfarin (Coumadin), which has a number of challenges, Bullock said. For one thing, keeping patients in the therapeutic range is tricky, and literature suggests that as much as 50% of the time an AF patient is outside the range – either they are not thinning the blood out enough or they are thinning it out too much. Also, because AF patients tend to be older, there is a greater concern that they might fall and have internal bleeding because of the blood-thinning drug.

Bullock said the Watchman device is meant to be a permanent implant in the LAA, which he described as a small flap outside the left atrium that looks like a little thumb. After 45 days, the patient's left atrium heals over and the device isolates the left appendage from the left atrium, Bullock said, because the company believes that is where the clot forms. Thus, the device will essentially lower the patient's risk of stroke by blocking off that area.

Larry Haimovitch, president of Haimovitch Medical Technology Consultants (Mill Valley, California) and a regular contributor to MDD, said that for some patients Atritech's device would provide an important alternative to Coumadin.

"This is a very interesting area. We've never had any device closures for the left atrial appendage," Haimovitch told MDD.

But there are a lot of questions about the device that the company will have to answer for FDA, particularly about how safe it is and how successful it is in stopping strokes, Haimovitch said.

Of course the company is hoping the data from its PROTECT AF study will answer most of those questions. The study began in early 2005 and enrolled 800 patients at 60 centers across the U.S. and Europe. Bullock said the patients in the study who received the Watchman LAA device were taken off the blood thinner to see if the device reduces strokes and cardiovascular events as well as Coumadin.

"The PROTECT AF trial results are highly anticipated to all those who manage patients with atrial fibrillation, the most common sustained cardiac arrhythmia," said Vivek Reddy, MD, director of cardiac electrophysiology at the University of Miami. "We trust the data will support the approval of the Watchman technology, providing clinicians with an additional tool to manage patients with atrial fibrillation."

Also, Bullock said Atritech has enrolled its first patient into the Continued Access Registry at Washington Hospital Center (Washington) under the direction of Professor Horst Sievert and Ron Waksman, MD.

Atritech said it acquired intellectual property last year from ev3 (Plymouth, Minnesota) covering LAA closure devices.

"Having consolidated the relevant intellectual property covering LAA closure technology, completed the PROTECT AF trial and submitted the PMA, we are very well positioned for the next stage of our company," Bullock said.

And the company's investors certainly seem to think the technology has promise.

About a year ago Atritech completed a $22 million round of financing led by SightLine Healthcare Vintage Fund. At that time, the company said it had raised about $45 million in capital in the previous 18 months. That round of funding helped Atritech complete the enrollment phase of its PROTECT AF trial and prepare for the PMA filing for the Watchman device (Medical Device Daily, Sept. 6, 2008).

The company's other major investors include SplitRock Partners, Prism Venture Partners, Tullis-Dickerson Partners, The Vector Group, Thoma Cressey Funds and Affinity Capital.

If the Watchman device is approved, it shouldn't take long for it to be adopted.

"Interventional cardiologists are highly adoptive; they pick up new technology very, very quickly," Haimovitch said.

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