Bio stents are more likely to cause heart attacks than metal stents
Many cardiac patients use a so-called stent due to their illness. These “vascular supports” ensure mechanical stabilization of the vascular wall. Biodegradable stents have also been used for some years. But researchers from Switzerland have now found that this increases the risk of heart attack.
Stabilization of the vascular wall
With narrowed blood vessels and hardening of the arteries in the heart, the insertion of stents is part of the standard therapy. Such a “vascular support” is also often used for people with coronary artery disease or stroke patients. A few years ago, however, an investigation showed that some of these medical implants could increase the risk of another stroke. And now scientists from Switzerland are reporting that bio-stents increase the risk of heart attack.
Ideal stent for the treatment of constricted coronary arteries
Since the first successful use of a balloon catheter in 1977, researchers worldwide have been looking for the ideal stent for the treatment of constricted coronary arteries.
There was great hope for a polymer stent made of lactic acid, which was approved in 2011 and will completely dissolve within three to four years.
"The stents used so far help the patient well, but they remain in the vessel for the rest of their lives," explained the director of the cardiological university clinic at the St. Josef Hospital in Bochum, Prof. Dr. Andreas Mügge in a press release years ago.
“We are pleased to be able to treat narrowed vessels that are ill in the future without leaving long-term residues. We give the vessel the opportunity to regenerate itself, ”says the doctor about the stents that dissolve.
However, current studies now show that the biodegradable stent does not keep its promise, but actually increases the risk of further heart attacks in the medium term. Cardiologists from the University Clinic for Cardiology at Inselspital Bern have now found out why.
Product has been withdrawn from the market worldwide
According to a message from the researchers, it was originally hoped that the bio-stent would cause irritation of the vascular wall less frequently, since no foreign body remains in the vessel with the implant. The vessel should regenerate itself.
However, recent studies on the stent now show that bio-stents lead to significantly more complications - especially more than a year after implantation.
As a result, the manufacturer removed the product from the market worldwide a few weeks ago.
Fragments of the stent can fall into the bloodstream
It was initially unclear why complications occurred. Researchers at the Inselspital, led by cardiologist Prof. Lorenz Räber, have now discovered the cause.
In collaboration with universities in Europe and Asia, the cardiologists at the Bern University Hospital examined 36 patients who had suffered late bio-stent closures, i.e. over a year after implantation.
The cause only became apparent by means of optical coherence tomography, an imaging process that delivers almost microscopic images from inside the blocked vessel:
"We were surprised by the results," says Lorenz Räber. "Even though the stents were correctly implanted, we saw the stent structure breaking into the inside of the vessel." The stent actually does what it was designed for: it breaks up into individual fragments.
“But if these fragments have not yet fully grown into the vessel wall, they can fall into the bloodstream as part of the dissolution process. There, this leads to a dangerous clot formation and thus to a heart attack. "
Blood thinners essential
“As a direct consequence of these results, we recommend our patients with such stents to continue diluting their blood with two platelet inhibitors. Over three to four years instead of normally one year, ”explains Räber.
"This is how we protect the bio-stent carriers from unexpected vascular occlusions."
The findings of the study, which was published in the "Journal of the American College of Cardiology", are also important, according to the scientists, in order to improve subsequent models.
Thinner stent struts and faster resolution would be important improvements to solve the current problems. (ad)