In a recent New England Journal of Medicine (NEJM) editorial, Debabrata Mukherjee, MD, chief of cardiovascular medicine and chair of the Department of Internal Medicine at Texas Tech University Health Sciences Center El Paso, commented on bioresorbable stents, an alternative to the traditional stents used in patients with cardiac conditions. In his editorial, Mukherjee encouraged cardiologists to continue using conventional drug-eluting stents instead of the newer bioresorbable option.
Conventional stents have had their drawbacks for years. Made of stiff metal, the round, tubular structure is inserted into a narrowed artery to open up the pathway and improve blood flow. The drug-eluting stent is a step above this bare-metal structure; it’s a device coated in an anti–tissue-growth medication that is slowly released into the bloodstream upon insertion, preventing the recurrence of blockages.
“If you think about it, stents are pieces of metal that are permanently placed into the heart, and people were not born with metal in their hearts; it’s not normal, and it may sometimes cause problems,” Mukherjee explains. “Just by being there, the stent will affect the blood-vessel lining.”
Blood clots and scar tissue are more likely to form where a stent has been placed. There is also a possibility that the stent will fail and that the artery will become blocked again at the same location––an effect known as restenosis.
“That’s why bioresorbable stents were invented,” Mukherjee says. “The premise is that you want to put in a stent that will go away completely after a few years, fixing the problem of potential side effects.”
The first bioresorbable stent was approved by the FDA in July 2016. Marketed by Abbott as the Absorb GT1 Bioresorbable Vascular Scaffold System, the device dissolves in the body three years after implant, helping the artery heal more naturally. But this popular device may not live up to expectations, according to Mukherjee.
In a clinical study published in March in NEJM, the Absorb system was associated with an increased risk of device thrombosis—a dangerous adverse effect in which a blood clot forms on the stent itself. While thrombosis occurred in eight patients treated with a drug-eluting stent, clots were observed in 31 patients receiving an Absorb implant.
In his review of that study, Mukherjee wrote: “Because the current generation of metallic drug-eluting stents is associated with excellent outcomes, there is little rationale to use bioresorbable vascular scaffolds at this time.”
“Bioresorbable stents cost more than the typical metallic stent, and they take longer for cardiologists to insert,” he added. “They are also no more effective, and less safe. As a physician, why am I going to use something that costs more if it can cause risk or harm to my patients?”
He noted that while long-term anticlotting medications may reduce the thrombus formation associated with Absorb stents, the potential for bleeding is likely not worth the risk.
Mukherjee acknowledged that bioresorbable stents are a good idea in theory, and hoped that the next generation of the devices will have improved results. He recommended that manufacturers focus on creating stents with faster reabsorption rates, thinner struts, and improved strength.
Source: Medical Xpress; April 6, 2017.