A U.S. Food and Drug Administration advisory panel on Wednesday urged the agency to reject a new “heart sleeve” surgical device, saying they had not seen enough evidence of benefit for patients with Heart failure.

The panel of experts voted 9-to-4 against approving Minnesota-based Acorn Cardiovascular Inc.‘s CorCap, a device already approved in Europe.

The device is a mesh wrap designed to fit around enlarged and weakened hearts often seen in patients with cardiac failure. It’s snug fit acts like a hose, supporting the heart and allowing it to reduce in size.

The company billed CorCap as an additional treatment for patients with worsening Heart failure despite treatment with multiple drugs.

A trial in 300 patients showed that people using the device experienced significant reductions in heart size, a sign cardiologists look for as an indication of improved heart health.

Patients receiving CorCap were also more likely than control patients to avoid later major heart surgery including transplants. Those that got the device had an 11 percent chance of major heart surgery after two years versus a 26 percent chance for controls.

FDA officials said those results might be biased by surgeons less willing to order second surgeries in patients wearing the heart sleeves.

Panelists said they were troubled by the company’s lack of ability to show that the device’s benefits translated to extended life for patients.

Fourteen percent of patients using CorCap died after two years, roughly the same number that died without using the device, according to Acorn.

“I think that there’s promise here, but we have not had a clear demonstration of benefit,” said Dr. John Somberg, a member of the FDA’s Circulatory System Devices Advisory Panel from Rush University in Chicago.

Dr. Robert Califf, a member of the panel from Duke University, said that he voted against approval because Acorn’s data did not make clear which patients might benefit from the sleeve. “It’s an astounding amount of uncertainty,” he said.

Steven Anderson, Acorn’s director of regulatory affairs, said the company will “quickly” enter talks with FDA officials over CorCap data and that he believed the agency “is ultimately going to determine that CorCap is safe and effective.”

Acorn has marketed CorCap on a limited basis since approval in Europe. Less than 340 patients have used the device since approval in the fall of 2000.

The company remains “determined to get this product to market,” Anderson said.