WASHINGTON (Reuters) - U.S. health regulators said on Wednesday they would limit the use of Stryker Corp's artery-opening stent for the brain to a narrower group of patients, based on new data and safety information.

The U.S. Food and Drug Administration changed the label for the stent, called the Wingspan system, after most outside advisers to the agency in March recommended the device should not be used in the majority of patients. A study last year showed it caused more harm than anti-clotting drugs.

Wingspan is used to open blocked arteries in the brain when clot-dissolving drugs like aspirin and Plavix do not work. The stent is supposed to improve blood flow and prevent people who have already had a stroke from having another one.

Plavix, known generically as clopidogrel, is made by Bristol-Myers Squibb Co and Sanofi SA.

But a study published in the New England Journal of Medicine showed the stent may actually do more harm than treating people with drugs and lifestyle changes.

Some of the FDA's advisers called for the device to be withdrawn from the market, where it has been sold since 2005.

But the FDA said the stent could still be useful for patients who have had multiple strokes despite taking medications. People must also not have had a stroke at least seven days before getting treated with Wingspan.

"Patient benefit is an important factor in agency decision-making," Dr. Jeffrey Shuren, head of the FDA's devices center, said in a statement.

"After careful consideration of available safety information, the FDA believes this device should remain available for this specific subgroup of patients who have exhausted other options," he said.