A coronary stent that slowly dissolves over time — vanishing in the fashion of biodegradable sutures and absorbable bone screws — has won the approval of federal regulators for use in patients with cardiovascular disease.
Conventional stenting has already changed the treatment of cardiovascular disease worldwide over the past two decades and in this country has led to the expansion of hospital cardiology departments and the specialty of interventional cardiology.
Medical device regulators at the U.S. Food and Drug Administration approved the dissolving stent, technically known as the Absorb GT1 Bioresorbable Vascular Scaffold System, last week.
More than 500,000 conventional stents are implanted annually, according to statistics from the National Heart, Lung and Blood Institute. Whether conventional or biodegradable, stents prop open blood vessels to restore blood flow, providing relief from blockages caused by biological goo — plaque that has collected over years.
The newly approved device was widely studied on Long Island and elsewhere in the metropolitan area as part of a clinical trial process aimed at determining its effectiveness and safety.
“The advances in stents have been dramatic,” said Dr. Thomas Pappas, director of the cardiac catheterization laboratory at St. Francis Hospital in Roslyn. Metal stents have evolved from bare metal devices two decades ago to metal scaffolds in more recent years that are coated in medication to prevent reclogging.
With bare metal stents, scar tissue was known to form within the device, leading to re-narrowing, a condition called restenosis, Dr. Bram Zuckerman, director of cardiovascular devices at the FDA, said last week.
So-called drug-eluting metal stents relieved restenosis but patients lost some flexibility in vessels with metallic stents, small cylindrical mesh-like devices that become permanent implants. The new ones are somewhat bulkier but vanish from the implant site within two to three years, Pappas said.
Both types are deployed in a vessel during coronary angioplasty, a minimally invasive procedure during which an opening is made in a blood vessel of the groin, arm or neck to allow passage of a fine, flexible tube called a catheter. That tube has the stent on the tip of a deflated balloon, which the cardiologist guides to the site of blockage. The balloon is inflated to deploy the stent. The catheter and balloon are removed.
Pappas said the absorbable device is not the be-all and end-all of stenting.
“I think it will have a role,” Pappas said. “But I don’t think it will replace the metallic ones, which have really transformed how we treat coronary artery disease.”
Dr. Luis Gruberg, who led clinical studies of the device at Stony Brook University Hospital, said the newly approved stent can’t be used in all types of blockages.
“From our experience with the stent, it is not applicable in every situation. It can’t be implanted in small arteries or those that are hard to reach,” said Gruberg, a professor of medicine and director of interventional cardiology research.
“This is the first generation of these stents, so as time goes by, I am sure that we will have better ones,” Gruberg said.
But the new stent’s absorbable quality, Gruberg added, allows a vessel the possibility to reclaim some of its flexibility once the device is gone.
Pappas sees other possibilities: “This may be a good option for people who need multiple stents and with this type of platform, patients can avoid the layers and layers of metal.”