Clinical trials bring disappearing stents one step closer for patients facing amputation
A new concept could help restore hope for patients at risk of losing their legs due to blockages in the arteries and prevent extra surgeries down the road.
University Hospitals Harrington Heart & Vascular Institute is part of a trial studying bioabsorbable stents for use in patients' legs below the knees. These stents, which Dr. Mehdi Shishehbor describes as scaffolds, restore blood flow, heal wounds and can even prevent amputation.
Traditional stents are made from nickel and titanium. When a balloon is inserted into a blockage, the blockage is pushed to the walls of the artery, Shishehbor explained. But as soon as the balloon is removed, the blockage recoils and returns. That's where a stent serves its purpose as a scaffold to reduce shrinkage.
Similar to bypass surgery to fix blockages in the heart, stents can be inserted in the legs. The difference is the length. While heart blockages are millimeters in length, Shishehbor said leg blockages can be 30 to 40 centimeters. Traditional metal stents, which remain in the body forever, can fracture or cause scar tissue.
Shishehbor, who has been a contributing principal investigator for the study and trial, noted the significance the stents could have on patients with Chronic Limb-Threatening Ischemia, a severe stage of peripheral artery disease. The majority of these patients are diabetic with blockages in their arteries putting them at risk of losing a limb.
"We have always had an interest, is it possible that we can put on a scaffold, like a stent, that has medication on it accurately to deal with the blockage? But over time, that stent would basically vanish, will dissolve and go away so that if the patient comes back a year and a half, two years, five years, 10 years, you are basically back to the normal artery that we had found before putting a stent," Shishehbor explained.
The new stent under trial is made from polyethylene glycol, meaning they'll dissolve over a period of months when they're no longer needed to provide structure, Shishehbor said. He added this could be a game-changer because it offers doctors another tool to open up patients' arteries in a safe way that saves time in the long run because patients won't have to return for additional procedures or complications like fractures.
"The beauty of this technology is that we can offer the drug and the scaffold, but then we have the benefit of the stent going away and not having to worry about having long stents in these small arteries below the knee for life," Shishehbor said.
The concept of bioabsorbable stents isn't new. The idea began about 20 years ago and a previous concept even received U.S. Food and Drug Administration approval in 2016, but it was scrapped due to cost and overall effectiveness, according to Shishehbor. The concept for the new stents began about four years ago and trials started two years ago.
The next step is FDA approval, which Shishehbor said can take six months. Highlights from the study were shared at the Transcatheter Cardiovascular Therapeutics conference in San Francisco on Wednesday, and Shishehbor hopes the positive results will bring the stents one step closer to patient use.
"That's the Holy Grail," Shishehbor said. "That's the most important aspect of why we do research — to get the technologies at the hands of patients and physicians so they can treat these patients and prevent amputations."