(Adds study details, background, analyst, doctor comment)
By Bill Berkrot and Ransdell Pierson
WASHINGTON, March 29 (Reuters) - Medtronic Inc's minimally invasive CoreValve system for replacing diseased aortic heart valves led to a significantly higher survival rate after one year than traditional open heart surgery in patients deemed at high risk of death during surgery, according to data from a study presented on Saturday.
One year after receiving the CoreValve in the 795-patient Phase III trial, the rate of death was 14.2 percent compared with a 19.1 percent death rate in the surgery group, researchers said. The result, presented at the American College of Cardiology scientific meeting in Washington, was deemed to be statistically significant.
There was also no increased risk of stroke seen with CoreValve compared with surgery, which had been one of the main concerns of transcatheter aortic valve replacement (TAVR) early on in clinical testing.
"I think the results were outstanding," said Dr. David Adams, a co-principal investigator of the CoreValve trial.
TAVR systems use a catheter threaded through an artery to the heart to put the new valve in place, sparing patients chest-cracking open-heart surgery and typically longer hospital stays associated with the invasive surgical procedure.
Early on, Adams explained, the question was could TAVR be an alternative as good as surgery. "Now, it might be better," he said. "We're making continual progress. It's not only an alternative but may be a preferable alternative."
CoreValve won U.S. approval in January, three months earlier than expected, to treat patients deemed too frail to endure open heart surgery, known as extreme-risk patients.
The latest results in high-risk, or less ill, patients should help expand the approval to treat a larger group as Medtronic competes with Edwards Lifesciences Corp's Sapien valve replacement, the first to gain U.S. approval.
Both have been available for several years in Europe, where medical devices tend to get approved far more quickly.
"A positive outcome in the CoreValve high-risk trial should lead to approval in this patient population in the U.S. by the end of 2014," Wells Fargo analyst Larry Biegelsen said in a research note prior to release of the data.
The U.S. Food and Drug Administration has determined that data from the study would be sufficient to make an expanded approval decision without first convening an expert advisory panel to discuss it, Medtronic said.
In addition to the survival result, the rate of major adverse cardiovascular and cerebrovascular events was significantly lower with CoreValve - 20.4 percent versus 27.3 percent for surgery. That was a combination of death from any cause, heart attack, stroke or need for another procedure.
More than twice as many patients in the surgery group went on to develop atrial fibrillation, a potentially dangerous irregular heart beat, researchers reported.
More than 100,000 people in the United States have severe aortic stenosis with about one-third too ill or frail for open-heart surgery, making them potential TAVR candidates. Patients are typically older than 80 years old.
Glenn Novarro, an analyst with RBC Capital Markets, estimated the U.S. TAVR market to be worth about $450 million in 2014. As positive clinical trial results mount in less extreme risk patients and physician acceptance increases, sales of the systems could provide important growth drivers for Medtronic and Edwards.
"I think TAVR is going to have broader acceptance for increased risk patients," said Adams, chairman of cardiothoracic surgery at Mt Sinai Hospital in New York.
The primary difference between the two systems is that Sapien uses a balloon, such as those employed in angioplasty procedures, to expand the valve once it is in place. The Medtronic system uses a special alloy that self expands as it reacts to body heat once the valve is in place. CoreValve also uses a smaller catheter than the currently approved Sapien. But the next generation Sapien XT device with a smaller catheter is expected to gain U.S. approval in the coming months.
Doctors and investors may get a glimpse of how the competition will shape up later at the ACC meeting, when German researchers present results of a head-to-head study comparing CoreValve with the Sapien XT.
Quality of life measures with those who received CoreValve were deemed to be non-inferior, or about as good, as those whose valves were surgically replaced.
There were some disadvantages reported in the CoreValve patients, including a low but significantly higher rate of valve leakage and a higher rate of need for permanent implantation of a pacemaker.
Adams said those issues were minor given the survival advantage demonstrated in the trial.
"The message is very clear," he said. "It was a superior outcome." (Reporting by Bill Berkrot and Ransdell Pierson; Editing by Elaine Hardcastle and James Dalgleish)