Biodegradable stents increase heart attack risk

Bio-stents are more likely to cause more heart attacks than metal stents

Many heart patients are using a so-called stent because of their illness. These "vascular supports" provide mechanical stabilization of the vessel wall. Biodegradable stents have also been used for several years. But researchers from Switzerland have now found that this increases the risk of heart attack.

Stabilization of the vessel wall

The use of stents is standard in narrowed blood vessels and arteriosclerosis in the heart. Also, people with coronary heart disease or stroke patients is often used such a "vascular support". However, a few years ago, an investigation has shown that some of these medical implants can increase the risk of another stroke. And now scientists from Switzerland report that organic stents increase the heart attack risk.

Biodegradable stents were considered ideal for treating narrowed coronary arteries. However, researchers have now found that these bio-stents increase the risk of heart attack. (Image: hriana / fotolia.com)

Ideal stent for the treatment of narrowed coronary vessels

Since the first successful use of a balloon catheter in 1977, researchers worldwide have been searching for the ideal stent for the treatment of narrowed coronary vessels.

Great hopes lay on a 2011-approved polymer stent made of lactic acid, which will dissolve completely within three to four years.

"The stents used to date help the patient well, but also remain in the vessel for the rest of life," said the director of the cardiology department of the St. Josef Hospital in Bochum, Prof. Dr. med. Andreas Mügge years ago in a press release.

"We are pleased to be able to treat contracted constricted vessels in the future in this way without leaving behind long-term residues. This gives the vessel the opportunity to regenerate itself, "the doctor told the stents that dissolve themselves.

However, recent studies show that the biodegradable stent does not live up to its promise, but even increases the risk of further heart attacks in the medium term. Cardiologists at the University Hospital of Cardiology at Inselspital Bern have now discovered why this is so.

Product was taken off the market worldwide

According to a statement by the researchers, it was originally hoped that irritation of the vessel wall would be less likely to occur due to the bio-stent, since no foreign body remains in the vessel with the implant. The vessel should regenerate itself.

However, recent stent studies have shown that bio-stents lead to significantly more complications - especially more than a year after implantation.

As a result, the manufacturer took the product from the market a few weeks ago worldwide.

Fragments of the stent may fall into the bloodstream

Why complications occurred was initially unclear. Now, researchers at the Inselspital have been led by cardiologist Prof. Dr. med. Lorenz Räber discovers the cause.

The cardiologists at the Bern University Hospital, in collaboration with universities in Europe and Asia, had examined 36 patients who had suffered late bio-stent occlusions, ie more than one year after implantation.

It was only by means of optical coherence tomography, an imaging technique that provided almost microscopic images from the inside of the blocked vessel, that the cause became apparent:

"The findings surprised us," says Lorenz Räber. "Although the stents were implanted correctly, we saw intrusions of the stent framework inside the vessel." Actually, the stent does what it was designed for: it dissolves into fragments.

"However, 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 thinner essential

"As a direct consequence of these results, we recommend our patients with such stents to continue the blood thinning with two platelet inhibitors. Over a period of three to four years instead of one year, "explains Räber.

"That's how we protect the organic stent carrier from unexpected vascular occlusions."

The findings of the study, published in the Journal of the American College of Cardiology, are also important, according to the scientists, to improve successor models.

Thinner stent struts and a faster resolution would be important improvements to solve the current problems. (Ad)