Treating narrowed or blocked heart arteries has evolved over the past 40 years. This week, the FDA approved the latest step in that evolution — a stent that dissolves away, leaving nothing behind.
Stents are devices that prop open an artery after an angioplasty restores blood flow through a narrowed or blocked artery. Stents have traditionally been tiny cages made of metal that remain forever in the artery. In contrast, the newest one on the market, the Absorb GT1 made by Abbott Vascular, gradually fades away.
This stent’s scaffold is built from a polymer called polylactic acid. The body breaks it down to carbon dioxide and water. After three to four years, it completely disappears.
Why does this matter? Foreign material in the body, like a metal stent, can trigger inflammation. That can lead to problems like the development of an artery-blocking blood clot or the formation of artery-clogging plaque. Eliminating foreign material takes that out of the equation.
An absorbable scaffold lets the artery return to its natural state, instead of being held in place by a stiff piece of metal. That section of the artery can then return to its natural curvature, and can dilate and constrict naturally.
Absorbable scaffolds may have a future use in children with narrowed or blocked blood vessels. A metal stent cages the growth of its part of the artery; an absorbable stent lets it grow naturally over time.
For some people, the new stent offers peace of mind. My patients often ask, “How long will I have this stent?” and worry about it being in the body until they die. Now I can tell them there is an option that will dissolve after a few years.
I see the Absorb GT1 as a new device, not as just another stent. It requires a different technique to deploy it and behaves differently during that process. And, of course, it disappears.
In the trial on which the FDA based its approval, the Absorb GT1 was compared head-to-head against the best-in-class metallic stent. The GT1 wasn’t any better than the traditional stent. It didn’t reduce the rate of heart attack or blood clot formation (thrombosis) or any other potentially harmful event. But it wasn’t worse either, except perhaps in people with very small arteries.
That trial lasted only a year. So it is possible that a few years from now we will see additional benefits from stent absorption. It is equally possible that we could learn about new risks.
The Absorb GT1 is the first of a new wave of absorbable stents. My colleagues and I have been working for more than a decade on a stent made of magnesium that the body breaks down and absorbs within a year. It was recently approved for use in Europe. Several other companies are developing different designs and materials for absorbable stents.
Research on these materials isn’t limited to their use in stents. Bioabsorbable materials are being developed to deliver drugs, create surgical meshes, repair joints, and more.
This new device isn’t for everyone who needs a stent. And it should be rolled out carefully — physicians must use it according to the established guidelines.
That said, I am keen to see what this unique device, and others like it, will play in day-to-day clinical practice.
Ron Waksman, MD, is director of cardiovascular research and education at the MedStar Heart & Vascular Institute at MedStar Washington Hospital Center and professor of cardiology at Georgetown University. He has been a consultant to Abbott Vascular and Biotronik, and was a principal site investigator for the ABSORB III trial.