Drug-Coated Stents Have Dark Side

Nov. 6, 2006 -- There's a dark side to drug-coated stents.

Drugs in the devices keep arteries from reclogging after balloon angioplasty -- a big problem with earlier, bare-metal stents. Introduced just three years ago, drug-coated, or drug-eluting, stents became all the rage among cardiologists.

But in rare cases, they seem to cause sudden cardiac death or severe heart attack a year or more after they're implanted.

Concern heightened with reports at last September's meeting of the World Congress of Cardiology in Barcelona, Spain. Despite reassurances that the risks are small, data presented at an October meeting of heart specialists in Washington, D.C., confirms there is a problem.

"There is a possible dark side to drug-eluting stents," Deepak L. Bhatt, MD, associate director of The Cleveland Clinic's heart center, tells WebMD. "The risk has been exaggerated -- but there is something there. People are not dropping in droves due to drug-eluting stents, but you can't say there is no cause for concern."

"It is a real concern," agrees Richard Milani, MD, head of preventive cardiology at New Orleans' Ochsner Clinic. "There are more questions than we have answers. We don't know how often this really happens. We don't really know who the people most at risk are," he tells WebMD.

How great is the risk? The data aren't in yet.

But in an analysis of clinical-trial data, Bhatt and colleagues found that over the course of a couple of years, patients who get drug-coated stents have 0.5% more risk of dangerous blood clots than those who get bare-metal stents.

"The absolute risk to an individual patient is less than one in 200," Bhatt says. But "with a million stents going in each year in the U.S. and twice that number worldwide, this is not trivial."

2 Steps Forward, 1 Step Back

For a person with a blocked artery, doctors have two basic treatments.

One is bypass surgery -- taking a blood vessel from somewhere else in the body and using it to bypass the blockage.

The other solution is to insert a catheter into the artery, inflate a balloon that reopens the blockage, and place a stent (or wire-mesh cylinder) in the blood vessel to hold it open while it heals.

As the artery heals, new cells grow over the inside of the stent, essentially making it part of the blood vessel.

Unfortunately, the body tends to see the stent as a foreign object. Sometimes, scar tissue forms inside the stent, once again blocking the artery.

New drug-eluting stents are coated with a polymer that slowly releases a powerful drug. This drug keeps scar tissue from forming.

Unfortunately, it also slows the healing process. That's a problem -- because until the blood vessel heals inside of the stent, there's a risk of deadly blood clots.