From: Reuters
Published February 6, 2008 08:34 AM

Stopping Plavix may carry early clotting risk

By Julie Steenhuysen

CHICAGO (Reuters) - Patients given the blood-clot preventer Plavix after a heart attack or after receiving a stent have a far higher risk of heart attack or death in the three months after they stop taking the drug, U.S. researchers said on Tuesday.

They found a cluster of heart problems occurring within 90 days of stopping the drug in people whose heart disease was treated either with drugs or a stent to prop open their arteries.

"It was almost a twofold increased risk in that initial period compared to later follow-up periods," said Dr. P. Michael Ho of the Denver VA Medical Center, whose study appears in the Journal of the American Medical Association.


People who have acute coronary syndrome -- an umbrella term for heart problems caused by reduced blood flow to the heart -- routinely get a prescription for Plavix, one of the world's best-selling medicines sold by Bristol-Myers Squibb Co and Sanofi-Aventis.

Known generically as clopidogrel, Plavix prevents blood clots that can cause heart attacks and strokes. It works by preventing disc-shaped elements of the blood called platelets from sticking together.

Some studies have suggested there may be a "rebound effect" of extra blood clots in the period right after people have stopped taking other anti-platelet drugs, including aspirin. Ho and colleagues wanted to see if this might be happening in patients taking Plavix.

His team studied 3,137 veterans with acute coronary syndrome who had been discharged with a prescription for Plavix after they had been treated either with a stent to open a blocked artery or with a combination of medicines designed to manage their heart disease.

They tracked the number of heart attacks and deaths in the three months, six months and nine months after people stopped taking Plavix.

Roughly 60 percent of subsequent heart attacks and deaths occurred within the first 3 months after patients stopped taking Plavix, regardless of how their initial heart episode was treated.

Ho said the overall risk was low. Of the 3,137 patients, 268 in the medically treated group and 124 in the stent group had a heart attack or died in that first three months after stopping the drug.

Ho said the finding supports the hypothesis of a "rebound period" of blood clots forming shortly after stopping treatment, but other studies would need to confirm this.

And he said this rebound effect might help explain why some studies have shown a higher incidence of blood clotting long after people with clogged arteries have been treated with a stent, a tiny wire mesh tube that props open arteries.

Ultimately, Ho said the findings do not offset the benefits of Plavix use. But if this rebound effect is found in other studies, doctors may need to reconsider how long patients take the drug and how they are monitored when they stop.

"If there is a rebound effect, we need to figure out how to prevent this from happening as we take patients off the medication," Ho said in a telephone interview.

(Editing by Maggie Fox)

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