Edwards Lifesciences recently completed enrollment of 350 patients in the non-surgical arm of its pivotal trial, studying the outcomes of patients who are receiving its transcatheter valve for the treatment of severe aortic stenosis, compared to patients who are using non-surgical treatments.

Note that both the non-surgical and surgical arms of the study have been ongoing since 2007.* The surgical arm of the trial compares the outcomes of patients using the transcatheter valve to those undergoing open-heart surgery. The clinical trial sites are continuing their enrollment of up to 690 surgical patients.

If results from the trials are good, Edwards' device will be the first valve of its kind to win approval in the U.S. in 2011.

The percutaneous valve, made from bovine pericardial tissue, is called the Edwards SAPIEN valve.

Cedars-Sinai Medical Center in Los Angeles is participating in the study, called the PARTNER trial, under the direction of Dr. Raj Makkar, director of interventional cardiology and Dr. Gregory Fontana, a cardiovascular surgeon. More than 20 medical centers in the U.S., including New York-Presbyterian Hospital/Columbia University Medical Center, are also participating in the trial.

In time, analysts say the valve will open a huge, new market for Edwards, as many people in need of a new left ventricular valve will no longer have to undergo open-heart surgery.

But for now, Edwards is trying to win approval for patients who are either at high risk for traditional open-heart surgery and for others who are not candidates for surgery at all, because they are elderly or have multiple co-morbidities, Cedars-Sinai's Dr. Makkar tells DOTmed News.

He explains that aortic stenosis is a condition where obstruction of the heart's aortic valve keeps it from opening properly and blocks the flow of blood from the left lower ventricle to the aorta. In severe cases, the blockage can prevent blood from reaching the brain. Patients with the condition often feel shortness of breath.

The stent-based valves are already hotly competitive in Europe, where the market for the device is growing rapidly. Edwards and Corevalve (recently bought by Medtronic) are locked in litigation over key components of the valve's technology.

However, in the U.S., Corevalve and the FDA have yet to agree on a study design for Corevalve's trial, analysts say. This means that Edwards' valve will likely have the edge among physicians in the U.S., before others can win approval.

Crimped on a Balloon

The minimally invasive technique "clearly has a very big advantage: being able to insert a valve without opening up the chest, in a beating heart, without the use of heart/lung bypass," Dr. Makkar says.

Explaining the workings of the valve, Dr. Makkar says that the Edwards SAPIEN valve is a frame; mounted inside the frame is a tissue valve that is crimped on a balloon. "You take this balloon, thread it through the artery in the groin and work your way into the heart. We position this valve at the site of the old valve and blow up the balloon, which pushes the old valve out to the side and the new valve instantly takes over all functioning."

Dr. Makkar adds that those patients who are too frail for this approach, called the femoral approach, can be treated with a balloon that is inserted through the chest. This is called the transapical approach. Edwards has a transapical valve that goes through the bottom (apex) of the heart and then is deployed.

"As time goes by, catheter-based implants will be used on a widespread basis," Dr. Makkar says. "And the technique may have cost advantages. The fact that patients heal faster means hospital stays are shortened." (The technique is performed as a partnership by an interventional cardiologist and heart surgeon.)

Bench-testing for Product Lifespan

At present, Dr. Makkar's team is bench-testing the valves to see how long they'll last. One of the major determinants of lifespan is how the leaflets--the doorways that push blood out of the heart but prevent regurgitation--are processed and repaired.

"The hope is that they would last as long as tissue valves. The metal and plastic valves last forever but you need to take a blood thinner if you're using a metal valve," he says.

Dr. Makkar estimates there about 750,000 people in the U.S. who suffer from aortic stenosis and says that 2 percent to 4 percent of Americans older than 65 have some degree of this disease. Only severe cases need to be replaced, Dr. Makkar says. There are about 25,000 Americans who fit into the "severe" category. This population is due to increase, as millions of boomers reach 65 every year.

Read more about SAPIEN and watch a video:
https://www.dotmed.com/news/story/7862/

*A Note of Correction: A previous version of this report incorrectly stated that the non-surgical portion of the PARTNER trial has just begun. In fact, both arms of the trial, surgical and non-surgical, have been underway since 2007. In device trials patients receive therapy as they are enrolled, unlike drug trials in which the entire cohort of subjects is enrolled and then treated.