Study: Catheter-delivered valve as effective as open-heart surgery

Dr. Larry Dean, a UW professor of medicine and surgery, is an expert in cardiac catheterization and interventional cardiology. He directs the UW Medicine Regional Heart Center.

For thousands of Americans whose aortic valve has become calcified and less functional, a catheter-delivered replacement valve appears as effective as highly invasive open-heart surgery, the conventional treatment.

So suggest results from the international PARTNER trial, which involved nearly 700 high-risk patients and 22 U.S. cardiology practices. UW Medical Center was the only study member site in the Pacific Northwest.

The April-released findings built on first-phase PARTNER results published in late 2010 in the New England Journal of Medicine. In a comparison of trans-catheter aortic valve implantation (TAVI) against standard medical therapy for patients deemed too ill for surgery, the results were striking: TAVI patients’ one-year survival rate was 20 percentage points higher than that yielded by medical therapy.

The trial’s more recent phase established that TAVI also is a viable alternative for patients for whom open surgery is an option but carries more risk, said Dr. Larry Dean, director of the UW Medicine Regional Heart Center and a study investigator.

“These devices are approved in Europe, but this is the first randomized trial between this device and surgery. That's why it's so important. This device was found to be non-inferior to surgery.”

In the trial, patients were randomly assigned to receive standard valve-replacement surgery or an Edwards Lifesciences aortic valve via catheter. After one year, 27 percent of the surgery patients had died, versus 24 percent of the TAVI patients.

Complete data for this phase of PARTNER have not been published but top-findings were revealed at the American College of Cardiology’s annual conference in April. Edwards Lifesciences funded the study and hopes results will persuade the Food and Drug Administration to approve the valve and catheter delivery system for broad use.

The Edwards Lifesciences aortic valve comprises three leaves of bovine pericardial tissue ringed by a surgical steel frame. Photography courtesy of Edwards Lifesciences, Irvine, Calif.

The study’s main downside for TAVI regarded stroke: In the first year post-procedure, 5.1 percent of those patients sustained a stroke or transient ischemic attack, versus 2.4 percent of the surgery patients. The main downside for surgery patients was increased bleeding – 25.7 percent versus 14.7 percent of TAVI patients at one year.

PARTNER II, to begin later this year, will more closely monitor strokes to distinguish between major, debilitating events and minor attacks from which patients recover entirely.

Even though PARTNER I is complete, UW Medical Center continues to provide TAVI for patients who meet the study’s inclusion/exclusion criteria. Over past 2.5 years, Dean and his fellow team investigators, Drs. Gabriel Aldea, Ed Verrier and Mark Reisman (based at Swedish Medical Center), have performed about 50 TAVI procedures.

“Our team includes surgeons, cardiologists and anesthesiologists, so we don’t have the same learning curve facing other practices who may offer the procedure someday,” Dean said

He anticipates that the FDA will green-light TAVI in 2012 but would not predict what corresponding indications – e.g., patient age, degree of stenosis, co-morbid conditions – will be approved. Also to be determined: what Medicare and Medicaid and other carriers might cover.

“One of the things we've learned through the trial is that, even though the aortic stenosis is fixed by the procedure, some of these patients are so infirm when they have the procedure that they need a much longer recovery time than they would have otherwise.

“As soon as a doctor confirms that a patient has severe aortic stenosis and may not be a good candidate for surgery, the patient should be referred, and sooner rather than later.”