Staying on Plavix Cuts Stent Risk

Dec. 5, 2006 -- The blood thinner Plavix may reduce the rare but deadly risks of drug-coated stents, but major questions remain, according to new research.

Stents are tiny mesh tubes used to prop open an artery after a balloon angioplasty opens a clog.

Bare-metal stents sometimes clog. Newer, drug-coated (or drug-eluting) stents don't clog nearly as often. But they take much longer to heal -- increasing the risk of a deadly blood clot.

That's why patients who get the newer stents get blood-thinning treatment with a combination of Plavix and aspirin. New data show that when treatment stops, problems start.

In one of the new studies, Swiss researchers Matthias Pfisterer, MD, and colleagues find that when patients stop taking Plavix, they have a small but serious risk of blood clots leading to death or heart attack.

"These side effects of drug-eluting stents are not frequent, but if they come, they may be heart attack or death," Pfisterer tells WebMD. But, he adds, "Patients should not be afraid of this treatment -- the risk has been exaggerated."

Stent Benefit, Stent Risk

Pfisterer and colleagues calculate the risk this way: If 100 patients get drug-coated stents, five will avoid major cardiac events within six months.

But if they stop Plavix treatment at this time, three patients will suffer heart attacks or death in months seven to 18.

On the other hand, for every year they stay on Plavix/aspirin treatment, two out of 100 patients will suffer drug-related bleeding problems.

Even so, the blood-thinning treatment may be worth it, a second study -- from Duke University -- shows.

Eric L. Eisenstein, Robert M. Califf, MD, and colleagues followed 4,666 patients who got bare-metal or drug-coated stents.

They found that extending Plavix/aspirin treatment cuts the risk of heart attack and death associated with the drug-coated stents.

The data "suggest that all patients with drug-eluting stents should continue to take [Plavix] for at least 12 months after [stent implantation], and possibly indefinitely," Eisenstein and colleagues conclude.

That's also the opinion of Carolyn M. Clancy, MD, director of the U.S. Agency for Healthcare Research.

"This study suggests that patients and their physicians should consider extending the period of use of this therapy while monitoring its effects very carefully," Clancy says in a news release.

The Eisenstein study appears in the Dec. 5 issue of The Journal of the American Medical Association.

The Pfisterer study appears in the Dec. 19 issue of the Journal of the American College of Cardiology.

Urgent Need for More Data

The Swiss study's data come from a reanalysis of a 746-patient clinical trial.

That trial was designed to compare drug-coated stents with bare-metal ones -- not to look at late-occurring side effects like clogged arteries. So Pfisterer warns the data can't be considered definitive.