TAVR in lower-risk patients looks likely but questions linger

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CHICAGO—Transcatheter aortic valve replacement (TAVR) is poised to move in a new direction—down, according to presenters at the Transcatheter Valve Therapies conference.

“We are at crossroads,” Martin Leon, MD, director of the Center for Interventional Vascular Therapy and Cardiac Catheterization Laboratories at NewYork-Presbyterian Hospital/Columbia University Medical Center in New York City, said in a kickoff session on June 4. “This is a point in time where clinical indications can be rapidly expanded.”

In the U.S., Edwards Lifesciences’ Sapien and Medtronic’s CoreValve TAVR devices have been approved for use in inoperable and high-risk patients with severe aortic stenosis. Two trials are under way to assess the safety and efficacy of TAVR valves in intermediate-risk patients. Leon serves as co-principal investigator of the PARTNER II trial, which will compare results from intermediate-risk patients treated with the Sapien XT and Sapien 3 systems.

“We know that people already are voting with their feet,” said Michael J. Reardon, MD, referring to a trend for Society of Thoracic Surgeon risk scores to drop over time. He is chief of the cardiac surgery division at Houston Methodist Hospital and principal investigator of SURTAVI, Medtronic’s trial in intermediate-risk patients.

STS scores of 4 to 8 percent are considered intermediate risk, yet data show that patients being treated under the high-risk indication in the U.S. are at 5 percent. “That is what people are doing right now, being labeled as high risk,” Reardon said.

Positive five-year results from the Partner 1A trial and two-year results from the CoreValve trial, both presented at the 2015 American College of Cardiology scientific sessions, have added impetus to the movement. Partner 1A showed that TAVR remained noninferior to surgery and provided a “midterm durability check,” Leon suggested. At two years, CoreValve proved TAVR in high-risk patients was superior to surgery for survival.

Going lower on the risk totem pole, studies using the Sapien 3 in in high- and intermediate-risk reported mortality rates of 2.2 and 1.1 percent and paravalvular leak rates of 3 and 4.2 percent, respectively.

Durability will remain a question mark for a while, given that the average age of patients in the inoperable and high-risk trials were in their mid-80s. Few are expected to survive long enough to demonstrate valve durability, Reardon said.

If TAVR is to shift to lower-risk patients, paravalvular leak also needs to be scrutinized, said Nicolo Piazza, MD, PhD, an interventional cardiologist at McGill University Health Center in Montreal. “We know that moderate to severe paravalvular leak occurs in less than 5 percent of patients currently, but still about 20 to 40 percent of patients have mild aortic regurgitation,” he said, basing the numbers on results from eight pivotal trials. “I think this remains a lingering concern for lower risk patients.”  

The annual three-day conference was organized by the Cardiovascular Research Foundation.