Florida invloved in testing of dissolving stent could revolutionize treatment of hear disease
Irene Maher, SCRIPPS HOWARD NEWS SERIVCE
3:54 PM, Jan 8, 2014
About six months ago, David Petrantoni's heart started fluttering.
"It felt like it would race a little bit, then be normal. Then it would do it again," said the Tarpon Springs, Fla., home builder. "That went on every once in a while for a couple months."
Because he'd been treated for a blockage in his heart five years earlier, Petrantoni, 54, knew he should take the fluttering seriously, so he went to the doctor. After several inconclusive tests, he went in for a catheterization to pinpoint the cause of his symptoms. That's when doctors found a vessel 85 to 90 percent blocked.
This time, instead of treating the blockage with a standard metal stent, Petrantoni was offered a new, experimental device. Unlike his first stent, this one is made of a material that will eventually disappear. Yet it should leave patients with an open, normally functioning artery, with no telltale signs of trouble or treatment.
The device, called the Absorb Bioresorbable Vascular Scaffold, is the first of its kind. It's being tested at more than 180 medical centers across the country.
"Studies show that these (Absorb) treated arteries heal as though there was never a problem, as if there was never a blockage. The stent dissolves so you won't pick it up on imaging later," said Dr. Patrick Cambier, Petrantoni's interventional cardiologist and a co-principal investigator in the Absorb III clinical trial at Morton Plant Hospital in Clearwater.
Because the device is being studied, patients like Petrantoni who agree to try it don't actually know yet if they've received Absorb or a traditional stent. That's a key research tool to be certain that results are not skewed by a patient's belief about what his treatment entailed.
Arteries in the heart become narrow or blocked by deposits of fat and cholesterol circulating in the blood. It's potentially dangerous because a blockage can reduce or completely block blood flow to the heart, causing symptoms such as chest pain, shortness of breath with exertion and the fluttering that Petrantoni experienced. It can also lead to a heart attack.
To open a narrow or blocked vessel, doctors place a thin wire fixed with a tiny balloon into the blockage and inflate the balloon, pushing the cholesterol deposits against the walls of the vessel. Then a drug-coated metal mesh tube, called a stent, is deployed to support the now-open vessel and release medication to help prevent formation of another blockage.
Traditional stents are meant to be permanent, even though they are needed for just a short time. "After about six months the healing is done and the stent has done its job, with one problem," said Cambier. "We're leaving behind hardware, a foreign metal object, in this moving, flexible, coronary artery, even though the artery is healed and there's good blood flow."
Because traditional stents are stiff, they can't respond to the natural action of arteries, which expand and contract depending on the body's need for increased blood flow during exertion.
Absorb is known as a scaffold, not a stent, because it is temporary. It's made of polylactide, found in other medical applications such as dissolving sutures used to close wounds. Like traditional stents, Absorb is coated with a drug that helps prevent re-narrowing, or restenosis, of the artery for about two months.
It starts dissolving in six months and is gone completely by 24 months. "Having the ability to treat an artery with severe disease and then have that artery return to normal, so it becomes like it was decades before the atherosclerosis developed, that is very appealing. I'm optimistic about this device," said Dr. Bernardo Stein, an interventional cardiologist and co-principal investigator on the Morton Plant study who was also involved in Petrantoni's case. "It's already being used in Europe and Asia. It's just not approved here yet. But there's a great deal of interest."
Morton Plant has had more than 20 patients sign up to participate in the trial since August. The trial is called single blinded because, while patients don't know what type of device they receive, the physician who places it does know, since they look very different, Stein said.
"You can't see the (Absorb) when it's placed because it isn't made of metal,'' he said. "So you don't see anything, only very small markers at the ends of the device, tiny dots, which show you its location."
Petrantoni had his stent procedure in August and went home the same day. Though a little sore, he went to a boat show the next day and resumed job-related computer work a few days after that.
"Technology is amazing," he said. He does think a little about the uncertainty of being in a medical trial, but simply hopes that whichever device he received continues to do the job.
"I feel good. I'm jogging. I'm exercising. I'm back on the job site building homes," he said.
( Contact Irene Maher at firstname.lastname@example.org. Distributed by Scripps Howard News Service).
(Distributed by Scripps Howard News Service, www.shns.com)