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Stents are used to keep coronary arteries open after a procedure called angioplasty. Some stents contain medicine that is released over time. It was thought that these stents would be more effective than plain metal ones, but early studies showed patients who had medicated stents were more llikely to have a heart attack than patients who got plain stents. Now there's a new generation of stents that release medication and a new study about their performance.

A heart stent is a mesh tube made of metal that, when inserted into an artery, keeps it open.

Stents can be metal only or they can contain medicine released once the stent is in place.

These are called drug-eluting stents. And the medication they release helps the artery remain open so blood can easily flow through it.

But studies show that even with drug-eluting stents, some patients still have heart attacks. And earlier studies concluded that drug-eluting stents could actually increase the risk.

Dr. Stephan Windecker heads the interventional cardiology program at Bern University Hospital in Switzerland. He organized a study on a new generation of drug-eluting stents and compared them to the plain metal variety.

“There were concerns that, actually, these drug-eluting stents may lead to adverse events such as occlusion [closing] of the artery with blood clots," said Windecker.

Dr. Windecker and other researchers studied more than 1,000 heart patients who were having an emergency heart procedure. About half received a bare-metal stent while the rest received the latest medicated stent. The medicine was on a biodegradable substance.

“That is a polymer which degrades into water and carbon dioxide during a period of six to nine months after the drug has been released and renders the stent surface more closely to a bare-metal stent," he said.

A year later, the researchers found those who got the drug-eluting stent had fewer heart problems than those who received the bare-metal variety.

“The occurrence of new heart attacks within that treated segment was slower with the biodegradable polymer as compared to the bare-metal stent, and it reduces the incidences of serious cardiovascular events by more than 50 percent," said Windecker.

Dr. Windecker says these newest drug-eluting stents made with polymers that dissolve are better than other medicated stents made with polymers that don't dissolve.

Ideally, a layer of cells that lines the artery will grow over the stent, making it, in a sense, part of the body.

The study was published in the Journal of the American Medical Association.

heart stent: 心臟支架

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（來(lái)源：VOA 編輯：Julie）