Study results are mixed for St. Jude anti-stroke heart plug

  • Article by: JAMES WALSH , Star Tribune
  • Updated: October 29, 2012 - 9:15 PM

Market analysts and the company say the device's benefits still are promising.

The study results were expected to boost the prospects of St. Jude Medical's device that plugs a hole in the heart to prevent strokes. They didn't. Too many people dropped out of the years-long study to make the results statistically significant.

The device, called the Amplatzer PFO Occluder, was shown to reduce the risk of stroke by 46.6 percent to as much as 72.7 percent when compared to patients who were treated with medication only. But because the study didn't meet its goal, the device's once-promising U.S. prospects now are considered a bit more "wait and see."

Thom Gunderson, a senior analyst with Piper Jaffray & Co., said: "The Street is split," and pointed out that St. Jude's stock price fell about 4 percent after the company announced study results last week. But, he said, many doctors remain convinced that the plug has potential.

"Cardiologists thought it was a good trial," Gunderson said. "For the doctors I talked to, it remains a viable option for them."

And Little Canada-based St. Jude isn't giving up hope either.

"We remain very encouraged because it is a complex patient population and it was a very complex study design," said Pamela Simons, a vice president of clinical affairs for St. Jude Medical. "I think that this provides a new set of evidence for patients and clinicians to discern."

Simons said the study results will be used to support the company's application to have the Amplatzer approved.

In a note to investors, Danielle Antalffy, with Leerink Swann Research, said the mixed results of the study "seemed to raise the question of how to identify the appropriate patient to treat, likely driving the industry to seek even more data still and limiting near- to medium-term market growth."

How it works

The plug is made of mesh and polyester. It is threaded into the heart through a vein in the leg. The device, which is approved for sale in Europe, is meant to address a condition called patent foramen ovale (PFO), a dime-sized hole between the upper chambers of the heart. Some believe that the hole is linked to cryptogenic stroke -- a stroke of undetermined origin.

According to the World Health Organization, about 87 percent of all strokes occur when blood clots block the blood vessels to the brain. Up to 40 percent of those strokes are classified as cryptogenic. According to St. Jude Medical, PFOs are three times more prevalent in people who have had cryptogenic strokes.

Dr. John Carroll, director of the Cardiac and Vascular Center and Interventional Cardiology at the University of Colorado, presented the Amplatzer study results last week in Miami and said the device can make a difference.

"The patient population affected by cryptogenic stroke tends to be relatively young and healthy. PFO closure with the Amplatzer PFO Occluder is potentially a novel prevention strategy that may be superior to medications alone," he said. "Stroke is a devastating disease and we now have compelling evidence that shows a 46 to 72 percent risk reduction in recurrent strokes, which is meaningful for this otherwise healthy patient population with a long life expectancy."

St. Jude's trial, dubbed "Respect," began in 2003 and enrolled 980 patients at 69 centers across the United States and Canada. All patients in the study had suffered a cryptogenic stroke. The study was to see if the device could prevent a second stroke.

Participants were randomly assigned to one of two groups -- the Amplatzer group and a medication-only group. All patients were monitored at one month, six months, 12 months, 18 months, 24 months and annually thereafter. But people dropped out of the study, leaving the groups uneven. That made it difficult to statistically compare. Patients will continue to be followed until the Food and Drug Administration makes a decision about whether to permit the Amplatzer to be sold in the United States.

Because the trial did not meet its "primary endpoint" of a statistically significant difference, Gunderson said, the FDA may require more data. Still, he said, many analysts and doctors he has talked to maintain a favorable impression of the device's safety and effectiveness.

"If any of us had the problem, we would absolutely have our PFO closed," he said.

James Walsh • 612-673-7428

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