Medtronic Inc. (NYSE:MDT) touted the latest results from studies of its CoreValve transcatheter aortic valve implantation system, which is two years behind competitor Edwards Lifesciences Corp. (NYSE:EW) in the U.S. market, at the European Society of Cardiology Congress 2011 conference in Paris today.

The CoreValve system is a minimally invasive treatment option for patients with severe heart disease who are at high risk or unable to undergo open-heart surgery.

The study followed 50 patients with aortic valve diseases who received CoreValve valve replacements in 2005 and 2006, and the device proved safe and effective after four years, the longest-term data available on any TAVI system to date.

Survival rate at two years was nearly 60 percent, and at four years it was about 45 percent. All patients saw improvement in their heart conditions, and there were no reports of fractures, valve migrations or valve deteriorations.

"These results reinforce that CoreValve is a sound and stable valve that holds up to real-world use," investigator Dr. Peter den Heijer said in the press release. "Almost more important, however, is that these patients – most of whom were old and very sick at the time of enrollment – saw such positive outcomes, including dramatic improvements in the activity level they could withstand, despite being some of the first patients in the world to undergo TAVI."

The device is cleared in the European Union, but "looks like a 2014 product for the U.S.," Medtronic executive VP and cardiac and vascular group president Michael Coyle said at the annual shareholders meeting.

CoreValve began a U.S. pivotal trial in December 2010, and enrollment began in March. "We are very pleased with progress of the CoreValve U.S. Pivotal Trial, as all trial sites have been activated and many sites are actively enrolling and implanting patients," MDT spokesperson Kathleen Janasz told MassDevice.

That puts CoreValve two years behind competitor Edwards’ Sapien valve, which got a positive FDA panel vote in July. Edwards has staked its flag on an October 2011 release, sinking about $40 million into a launch that Edwards’ chairman & CEO Michael Mussallem said will allow the company to compete in 200 to 400 medical centers in the U.S. 

Edwards and Medtronic have gone back and forth over valve patent disputes, most recently resulting in a $74 million patent infringement loss for Medtronic. A federal judge denied Edwards’ move to bar U.S. manufacturing and sales of CoreValve, which Medtronic acquired in in its $700 million buyout of CoreValve Inc. in 2009.

Here’s a roundup of recent clinical trial and scientific study news: