US FDA staff questions heart device data

U.S. health regulatory staff expressed concern about several issues with Atritech Inc’s data for its Watchman heart device to prevent blood clots, including the types of patients studied and how long they were followed.

Despite a positive statistical review, Food and Drug Administration staff pointed to more than a dozen “confounding issues” in their memo released ahead of an advisory panel meeting on Thursday to evaluate the device’s safety and effectiveness.

Privately held Atritech is seeking FDA approval for the cage-like device as a rival to the widely used blood-thinning drug warfarin in preventing strokes in patients with irregular heart beat, or atrial fibrillation. The Watchman aims to prevent harmful blood clots that form in part of the heart from entering the bloodstream and can cause a stroke.

Some stock analysts have speculated that the Minnesota-based devicemaker would be an attractive acquisition for larger medical technology companies if its device is successful.

On Thursday, the FDA will seek input from a panel of outside experts to help it evaluate the data. The panel will recommend whether or not to approve the device, but the agency will later make the final decision.

In its documents on Tuesday, the FDA pointed to a number of concerns, including the types of patients studied. The FDA said the company’s clinical trial “enrolled a select group of patients with atrial fibrillation” using criteria that “tended to exclude the patients at higher risk of poor outcomes.”

Because the device would be used to manage a long-term chronic condition, FDA staff said it was essential to show the device’s durability but noted there was only effectiveness data on 22 percent of the implanted patients after two years.

The FDA also pointed to several other potential problems in analyzing the data in its memo, which was posted on the FDA’s website at http://www.fda.gov/ohrms/dockets/ac/09/briefing/2009-4434b1-00-Index.html.

Atritech, in a separate document also released on Tuesday, said its data showed the Watchman was safe and effective. It added that the results found it was no worse than warfarin, a drug used by many patients with atrial fibrillation. The heart rhythm disorder creates clots and can increase stroke risk.

Warfarin, available as a generic and as Bristol-Myers Squibb Co’s branded drug Coumadin, is relatively inexpensive but carries significant bleeding risk. It can also be difficult to determine the best dose for patients, who must be frequently monitored.

In fact, several drugmakers, including Johnson & Johnson and Bayer AG , are also seeking new alternatives to warfarin.

Atritech’s expandable device ranges from the size of a penny to a half-dollar coin and is inserted near the heart’s left atrial appendage, isolating it where the vast majority of clots are formed, the company has said.

Previously released data from a company-sponsored trial showed Watchman was better at reducing the risk of Hemorrhagic stroke, which involves bleeding in the brain, than warfarin alone. But there were also more procedure-related complications, mostly due to implanting the device.

“In total, these results demonstrate that while there were procedural risks in the treatment, the risks were reduced as physicians became more familiar with the implant procedure,” Atritech said.

While inserting the device increased the time patients spent in the hospital, it “did not cause procedure related death,” it added.

Thursday’s panel is expected to address those concerns, training needed for doctors to implant the device and whether the company should be required to continue to study the device if it is allowed on the U.S. market.

By Susan Heavey
WASHINGTON (Reuters)