Medtronic Inc. said Thursday that its artificial heart valve has won FDA approval for use in more patients, a development that may give it an edge in the nascent market.

The product, called CoreValve, was approved in January for use in patients designated as facing "extreme risk" of death if they underwent open-heart surgery, the standard procedure for valve replacement. Now, doctors can use CoreValve in patients designated at "high risk" of death through surgery, a broader grouping.

The Food and Drug Administration granted the approval without requiring an advisory panel review. In March, researchers published findings showing that 86 percent of the patients designated as high risk who received the CoreValve implant were alive one year later, compared with 81 percent who received a new valve via open-heart surgery.

The findings also showed that postoperative risk of stroke was low and blood ­circulation was better. Those results helped expedite approval for use with the larger group of patients, Fridley-based Medtronic said.

"There is a lot of excitement among U.S. heart teams for the CoreValve System's high risk approval," John Liddi­coat, president of Medtronic's structural heart business, said in a statement.

Each year, about 550,000 people worldwide receive a diagnosis of severe aortic stenosis, a condition in which calcium buildup on a valve can prevent the heart from pumping blood properly. About 100,000 of those people are Americans and, of them, about 35,000 are designated at extreme or high risk of death from open-heart surgery. Half of the people who are diagnosed with the condition die within two years of the diagnosis.

Medtronic and Edwards Lifesciences Corp. are competing in the new market for heart valves that are inserted in a patient's body in a less invasive and dangerous manner than open-heart surgery. The valve is instead inserted via a catheter through an artery, usually in the thigh.

The companies last month settled a six-year patent dispute over transcatheter heart valves with a cross-license deal and agreement by Medtronic to pay Edwards about $1.1 billion through 2022, with $750 million upfront. That has spurred doctors to schedule more surgeries with the new type of valve.