High risk patients with severe aortic stenosis are benefiting from a minimally invasive aortic-valve replacement procedure more than expected, a new study shows.

Transcatheter aortic-valve replacement (TAVR) is a minimally invasive method that uses an expandable balloon to replace a severely diseased aortic valve in patients that are too high risk or otherwise unsuitable for open-heart surgery.

In the study, University of Pennsylvania researchers reported the first-year results of a study, which is ongoing. In it, they found an 85.6 percent all-cause survival rate at one-year follow-up in the 583 high-risk and inoperable participants. For those labeled high risk only, one-year survival was 87.3 percent and it was 82.3 percent in those considered inoperable only.

The survival rate was significantly higher than that of the original study, looked at patients with older devices. That earlier study found survival rates at 76 percent and 69 percent, respectively. However, this study was observational, and did not compare groups of patients in the same way that the earlier one did, the researchers noted.

"TAVR is getting better due to new design features, procedural improvements, operational experience, and improved patient selection,” the study’s lead author, Dr. Howard C. Herrman told Medscape of the results, which appear in Circulation.

"There are some questions about the durability of the valve and whether it's an ideal substitute for the for the more conventional, more durable valve in younger patients. But certainly this information and the excellent outcomes make it the preferred valve for older patients," Dr. Timothy Gardner, a past president of the American Heart Association, commented in the news report.