A minimally invasive alternative to open-heart surgery has become a competitive battleground for devicemakers who are racing to get new products into the market.

Boston Scientific unveiled encouraging data Monday on a transcatheter aortic valve replacement (TAVR) approach that would join products from Medtronic and Edwards Lifesciences of California in the marketplace. St. Jude Medical is in U.S. trials but said this weekend that it has stopped implanting devices while it examines potential problems turned up in early data.

If either Boston Scientific or St. Jude gets a product to market, it would change the dynamics for a product that currently commands a $32,500 price tag for both Fridley-based Medtronic and Edwards, based in the Los Angeles suburbs.

"That price will drop when the third valve comes out," said Dr. Stephen Ramee, a medical director in cardiology at Ochsner Medical Center in New Orleans and a leader with the American College of Cardiology. Ramee spoke by telephone from the 26th annual Transcatheter Cardiovascular Therapeutics meeting, which is organized by the Cardiovascular Research Foundation.

The aorta is the most important artery in the body, and several devicemakers are racing to develop less-risky ways to replace the valve that delivers blood to it. Medtronic surprised some analysts last month when it announced it had grabbed 40 percent of the TAVR market.

Open-heart surgery is still the preferred method of fixing a faulty aortic valve, but TAVR devices can be delivered to the heart through a small catheter tube snaked through an artery in the leg or chest.

Today the procedure is available only to patients with a high or very high risk of death from open-heart surgery, but industry boosters say it's only a matter of time before the minimally invasive procedure is available to patients at moderate risk of death, potentially opening up the procedure to a wider patient market.

Several companies are conducting trials and analyzing data for moderate-risk patients getting catheter-delivered aortic valves.

"I think it is realistic," said Dr. John Lesser, a cardiologist with the Minneapolis Heart Institute at Abbott Northwestern Hospital, which is a center for multiple clinical trials for TAVR devices. "I do think that in the longer term, probably the majority will be placed in the leg or in a small incision."

Device's life span unknown

Right now the biggest question is how long TAVR devices will work in the body. Traditional surgically implanted aortic valves can work between 15 and 20 years — longer than catheter-delivered valves have even been available in the United States. The industry hope is that the data from high-risk patients and moderate-risk patients in trials will shed light on whether TAVR products have comparable life spans, which would go a long way toward their widespread acceptance for most valve-replacement patients.

The aorta is the main artery delivering oxygenated blood to the rest of the body, and the aortic valve controls the pace of blood flow from the heart into it. The valve can narrow with age and develop into a diseased state called aortic valve stenosis, one of the most common forms of heart disease. Symptoms include chest pain, shortness of breath and fainting. Before the recent advent of minimally invasive technologies, cardiac surgeons typically opened a patient's chest and implanted either mechanical valves or ones created from animal organs.

"The vast majority of people with aortic stenosis are elderly. … Before this technology was known about, most of these people were unsuitable for surgery, and they languished and died," said Dr. Ian Meredith, a cardiologist with Monash Medical Center in Melbourne, Australia.

Meredith is the principal investigator on the Reprise II trial for Boston Scientific, and he presented data at the Washington conference Tuesday showing the Massachusetts company's Lotus valve system had positive results based on a study of 120 patients at 14 overseas sites. Lotus is available for sale in European nations, but not yet in the United States.

Meanwhile, officials at St. Jude are still hopeful about their Portico transcatheter valve system, despite pausing an ongoing U.S. trial after initial scans showed the leaflets that flex to produce blood flow to the aorta had less mobility than had been expected.

"Patient safety is our highest priority, so we have made the thoughtful and deliberate decision to stop implanting Portico devices until we complete our comprehensive analysis," a company spokeswoman said.

Joe Carlson • 612-673-4779