Surgery for certain bad heart valves may soon become a thing of the past. New studies have suggested that it is okay and it is even better to have a new valve placed through a tube into an artery instead.

The results of this study are expected to quickly transform the common treatment of a problem that affects millions of people which is a stiff or narrowed aortic valve that doesn't let blood pass. Until recently, fixing severe cases like this required a major operation using a heart-lung machine while surgeons cut out the old valve and sewed in a new one.

Years ago, expandable aortic valves were made so that it can be guided to the heart through a catheter into a blood vessel and placed inside the old valve. But they're only used now in patients that can't stand this type of surgery.The new studies tested these valves in patients that have low risk for the operation and found them as good or superior to surgical ones.

"This is our last frontier" to make these devices a standard of care, said Dr. Joseph Cleveland, a University of Colorado heart surgeon with no role in the studies or ties to the companies that sponsored them. "It's a great thing" for patients to be able to avoid major surgery, he said.

Results were published by the New England Journal of Medicine on Saturday and were to be discussed at an American College of Cardiology conference in New Orleans on Sunday.

One study shows that about 1,000 patients were given standard surgery or what is called an expandable Edwards Lifesciences valve. After one year, 15 percent of the surgery group had died, suffered a stroke or needed to be hospitalized. 

In the other study, 1,400 patients were given surgery or what is called a Medtronic expandable valve. Based on partial results, researchers recorded that after two years, 6.7 percent of the surgery group had died or suffered a disabling stroke.

In both studies, certain issues were more common with surgery, including development of a fluttering heartbeat called atrial fibrillation or major bleeding. In the Medtronic study, 17 percent of expandable valve recipients later needed a pacemaker versus 6 percent of people who had surgery.

Previous studies suggests that the overall costs are lower with expandable valves, which is about $30,000 versus $5,000 for surgical ones, largely because they require shorter hospital stays and caused fewer complications, said Cleveland, who also is a spokesman for the College of Cardiology.

In the United States, surgeries to replace aortic valves have been falling. Only about 25,000 are expected to be done this year and Cleveland expects that to drop by half next year and by half again in 2021.

He and other doctors say the expandable valves still need longer study to see if they can hold up as well as surgical ones.