There’s new evidence the latest generation of coronary stents--those that are coated with drugs--may in fact be associated with an increased risk of blood clots in the heart arteries they’re designed to keep open.

Coronary stents have been an incredible advance in cardiology. The latest type, those that are coated with drugs, help keep the arteries clear by preventing scar tissue from developing.

But now comes new worries over a delayed side effect: a blockage of these stents by clot formation. It has doctors wondering how to best address the problem.

“Well I had a feeling that my, like I had burning in my chest, I thought I had a respiratory infection, but that burning sensation what really angina.” Like millions of Americans, Abe Haiman has blockages in his heart arteries. But this week, he had a stent placed. They’re used along with the procedure angioplasty, where a balloon-tipped catheter is placed into a blocked coronary artery.

The balloon is inflated, pushing the clot aside.

A stent at the tip of the catheter is deployed at the site, and left in place to act as a strut to keep the artery from closing back off—a problem called restenosis.

It used to be that stents were simply bare metal, but over time these were associated with scar tissue development, blocking off the artery once again. Then came drug coated stents, which hit the market in 2003. They are now the standard of care.

These prevent the scar tissue from developing.

“And as a result, drug-eluting stents have brought down the likelihood of reoccurrence from maybe one in three to more like one in ten patients, are much more likely to have long term freedom from any reoccurring angina or heart attack after drug-eluting stents,” says Dr. Gregg Stone, a stent expert and researcher at Columbia University Medical Center.

But now, the latest research presented at a major cardiology meeting shows new evidence of increased blood clot risk in the long term.

“What we showed was that drug-eluting stents in one out of two hundred people may have a higher likely hood of getting blood clots inside the stent and this is sort of a late phenomenon that can happen one year, two years, three years after the procedure. The important thing to realize about that though is that it is a relatively small number one out of two hundred,” says Dr. Stone.

Many cardiologists are not convinced the risk is significant, and that the benefits far outweight any downside.

Others say this can’t be simply dismissed. Some doctors are going back to using bare metal stents.

“This is one side effect that we have to keep our eye on and it can usually be controlled and prevented with the proper kind of antiplatelet medicine,” says Dr. Stone.

Many are using those blood-thinning drugs for a longer period of time. The problem with drugs used to prevent clots like aspirin and plavix, which also acts on the platelets, the sticky cells, is that they have serious side effects, including bleeding.
But no one knows when is the right time to stop the blood thinning medicine.

Abe is counting on his stents.

“I have two coronary arteries that were clogged and that are now open,” says Abe. And he’s hoping they stay that way.

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