The Amplatzer PFO Occluder, which was invented in Minnesota, has been the subject of more than 13 years of clinical research and much debate. (The Minnesota Star Tribune)

A group of doctors convened by the Food and Drug Administration decided Tuesday that a new St. Jude Medical heart device to prevent strokes appears safe and effective, after more than 13 years of U.S. clinical research for the Minnesota-invented gadget.

By a 15-1 vote, the doctors on the panel said Tuesday that the long-running study showed a "reasonable assurance" that the Amplatzer PFO Occluder is safe for use. The same panel voted 11-5 that the device's benefits outweigh its risks, and 9-7 that it is effective for its intended use.

The wire-mesh device is intended to help prevent recurring ischemic strokes in people who have had at least one other unexplained stroke in the past and who have a hole between the upper chambers of their heart known as a patent foramen ovale (PFO). The only other therapy available today for PFO-related stroke is lifelong medical management with anti-platelet drugs or blood thinners.

"We've searched long and hard for new ways to prevent the risk of recurrent strokes in patients with a PFO, as these strokes can often be debilitating. For these patients, closure with the Amplatzer PFO Occluder is an important treatment option, and today is an important step toward approval of this technology in the United States," St. Jude Medical Chief Medical Officer Dr. Mark Carlson said via e-mail.

At an estimated cost of $5,000 per device, PFO occluders could comprise an annual market opportunity between $200 million and $350 million for St. Jude, depending on adverse-event rates, Wells Fargo analyst Larry Biegelsen wrote in a note to investors last week. St. Jude, which is in the process of being acquired by Abbott Laboratories, had $5.5 billion in revenue last year.

The quest to design a PFO-closure device to prevent stroke has become "one of the most controversial areas of cardiovascular devices/medicine over the past 10+ years, with strong proponents and equally strong critics," Biegelsen wrote.

The Amplatzer PFO Occluder was invented at Plymouth-based AGA Medical, which St. Jude acquired for $1.3 billion in 2010.

Ischemic stroke, in which a clot travels to the brain and obstructs blood flow, is one of the leading causes of major disability in the United States. Each year a subset of ischemic stroke patients, about 16,000 Americans, also has a PFO that may have allowed blood clots to cross from the heart's right atrium to the left and then advance into the brain.

St. Jude's PFO occluder uses two wire-mesh discs inside the heart to seal off the hole from both sides and prevent blood from flowing directly between the two upper chambers of the heart. The device is implanted using a catheter in the leg, rather than open-chest surgery.

The first U.S. patient was enrolled in AGA's clinical study of the device in 2003. It took eight years to enroll 980 patients, who then had to be followed for about five years each, which is why the trial lasted 13 years.

The results of that trial were debated extensively Tuesday by the doctors on the FDA panel.

An FDA summary of St. Jude's data noted that the randomized trial documented a lower stroke rate among the patients who got the device. But overall, the trial failed to meet its primary endpoint, which was a reduction in the rate of stroke so that only a quarter of the first 25 strokes happened in the group of patients who had the device implanted.

Nine of the patients who got or intended to get devices in the trial experienced nonfatal ischemic strokes in the five years after procedures, compared to 16 nonfatal strokes in the control group. About 4.5 percent of the patients who had or attempted to have a device implanted experienced a serious adverse event related to the device or procedure, the FDA summary said.

In its presentation to the FDA, St. Jude said the study documented a statistically significant 63 percent relative reduction in risk of stroke compared to medical therapy alone. The company noted that nearly all of the procedure-related serious adverse events were resolved without long-term complications.

Joe Carlson • 612-673-4779