Heart stents examined by FDA

Stents, tiny latticework like tubes that hold open clogged arteries have revolutionized the treatment of heart disease, enabling millions people to avoid bypass surgery.

But now the newest models, coated with drugs, are under the government microscope.

"Are you doing a drug eluting stent or a bare stent?"

Its estimated more than six million people have received drug-eluting stents, tube-like props coated with medicines as an extra measure to prevent arteries from clogging.

"Ok, we're going to stent boost"

Now the FDA is examining the safety of the coated stents amid growing research suggesting a risk of clotting one to three years after they are implanted.

"We did find a higher rate of stents clotting up with longer term follow-up with drug coated stents v bare metal stents," said Cleveland Clinic cardiologist and researcher Deepak Bhatt.

According to federal statistics, late stage clotting happens in three to four out of every thousand patients.

The Cleveland Clinic's Dr. Deepak Bhatt notes that while such findings raise a red flag they should not trigger panic.

"So the absolute risk to an individual patient is quite low, unless of course you happen to be that patient. So it's not an altogether trivial issue but should not be the cause for panic among either patients or their physicians, said Deepak.

A statement by the American Heart Association highlights research suggesting that poor patient compliance with follow-up drug therapy either blood thinners or long-term aspirin therapy plays a role. An FDA committee will review all the research and decide whether further study or new warnings are needed.

One big question the FDA will address is how long patients need to stay on blood thinning drugs after they get a drug-coated stint. Labels on the stints currently recommend six months.

But a study released this week out of Duke University found an increased risk of clots even in patients who stayed on blood thinning medicine for up to a year.

It's estimated that stents are implanted in 650,000 Americans a year. Since the first drug-coated stents gained FDA approval in 2003, they have gone on to capture 80 percent of the stent market.

The FDA said the risk of blood clotting applies to the drug-coated stents when used as labeled.

However, the agency acknowledges that more than 60 percent of the stents probably are implanted in types of patients not studied during the trials of the devices that led to their approval.

That off-label use often involves more complex cases; those patients may well benefit more from the drugs in the coated stents but also face greater clotting risk, complicating the issue.