TAVR | The field of cardiology continues to sail farther on the seas of medical care – and in ever-smaller craft. University of Colorado Hospital is part of the armada and will likely launch its first tiny vessel next month.
The hospital is a site for the PARTNER II (Placement of AoRTic TraNscathetER) clinical trial, which will test a new ultra-thin delivery system bearing a heart valve replacement that journeys via catheter through a small incision under the left breast.
The trial compares the safety and efficacy of a second generation of medical devices used for minimally invasive transaortic valve replacement (TAVR) procedures to traditional open-heart surgery. Like its predecessor, Edwards Lifesciences’ FDA-approved Sapien valve, the new, chromium cobalt-encased XT valve is crimped and sits at the tip of the flexible catheter next to a balloon.
Cardiothoracic surgeons make an incision, then work with a team of interventional cardiologists and imaging specialists, supported by cardiac anesthesiologists and nursing staff, to guide the catheter to the heart.
With the new valve positioned, the clinicians inflate the balloon and implant the valve. The team snakes the catheter back through the artery, removes it and closes the incision.
In PARTNER II, the XT valve rides a catheter that is more than a millimeter thinner than the one used to deliver the Sapien valve. Instead of having to go through the femoral artery, therefore, cardiothoracic surgeons can make a smaller, transapical incision in the breastbone, nearer to the heart.
A millimeter or so might not seem like much to the layman, but it can make a huge difference in the OR, where a narrow femoral artery can prevent the procedure from starting, said John Carroll, MD, director of interventional and vascular cardiology at UCH.
“That [millimeter] may be all we need to do the procedure,” Carroll said. With the original Sapien, “We couldn’t treat one in five patients because the femoral artery wasn’t big enough.”
PARTNER II not only extends clinical research into TAVR, it also expands the pool of patients eligible for the minimally invasive surgery, Carroll said.
The first PARTNER trial included only patients deemed too high risk to undergo open-heart surgery at all and patients who were operable but high risk, he said. PARTNER II will compare the transapical valve implantation procedure to open-heart surgery in patients at moderate risk, Carroll said. A second arm will use the new procedure to treat patients with surgically implanted valves that have degenerated. Clinicians will use the procedure to implant the new valve inside the old one.
Patients will be randomized, with two patients getting the TAVR procedure for every one getting open-heart surgery.
As a condition for reimbursement from the Centers for Medicare and Medicaid Services, each participating PARTNER II site must also submit data on the procedures it performs to the TVT Registry, a warehouse created by the Society of Thoracic Surgeons and the American College of Cardiology to track the outcomes of TAVR procedures. Carroll and Frederick Grover, MD, professor of Cardiothoracic Surgery at CU, are on the TVT steering committee.
“The idea is the data will provide an objective assessment of a center’s performance [with TAVR],” Carroll said.
Lorna Prutzman, RN, MSN, executive director of the hospital’s Cardiac & Vascular Center, said she expects to begin actively recruiting patients for PARTNER II in September. She said the hospital will begin running ads on National Public Radio beginning in October and will post information about the procedure on its public Web site (http://www.uch.edu/conditions/heart-circulation-conditions/valve-clinic/).
“We’ll also meet with community physicians and offer lectures on valve disease,” she said. She anticipates meetings next month with the hospital’s University of Colorado Health partner, Poudre Valley Health System (PVHS), to establish referral patterns and a course of care for PVHS patients who may be eligible for the PARTNER II trial.
In fact, with the closest trial sites to UCH being Salt Lake City; Kansas City and St. Louis, Mo.; and Lincoln, Neb., the hospital will be looking for eligible patients throughout the Rocky Mountain region, Prutzman said.
“We’ll cast a wide net,” she said.
A team of providers from the hospital’s multispecialty Valve Clinic will recruit patients on the basis of their interest in the trial and qualifying vessel-imaging studies. A national committee will then evaluate the candidates and select patients for the trial, Carroll said.
Although the hospital was not a trial site for PARTNER I, it has performed procedures on 21 patients who would have qualified for that trial, Carroll said. Two had femoral arteries that were too small for TAVR, he said, and received balloon valvuloplasties instead. All others received TAVR, with one major complication – a death within 30 days.
“That’s lower mortality than the trial,” Carroll said, “and we’ve had no strokes. We’re off to an excellent start.”
The hope is that the new device on trial in PARTNER II will decrease recovery times and complications resulting from “an older, larger technology,” as Carroll called the Sapien. Cardiothoracic surgeon David Fullerton, MD, and colleague Joseph Cleveland, MD, he said, have done well opening the femoral artery and in a couple of cases found alternate routes to spots higher on the femoral through the iliac artery or a space behind the peritoneum, which lines the abdomen.
Still, the simpler access route for the XT could reduce risk, Carroll said. With the new system, “There is no surgical cutdown of the femoral artery required in these very ill patients,” he said.