By Lisa Ellis
InteliHealth News Service

CHICAGO — Treatment with a second anti-clotting drug, in addition to aspirin, for up to a year after angioplasty reduces rates of death, heart attacks and strokes significantly more than aspirin alone, researchers said.

The report, which is being published in the Nov. 20, 2002, issue of the Journal of the American Medical Association, also was presented at the annual Scientific Sessions of the American Heart Association (AHA).

The study, which enrolled 2,116 patients at 99 centers in the United States and Canada, examined the effects of using clopidogrel (Plavix) for a longer term than the four weeks it typically is prescribed for patients after angioplasty.

The study was funded by a grant from the partnership of Bristol-Meyers Squibb Co. and Sanofi-Synthelabo, which manufacture and distribute the drug.

In angioplasty, a tiny balloon attached to a thin tube is threaded into an artery, and the balloon is inflated to open up the artery.

Blood clots are more likely immediately after the procedure, so clopidogrel often is prescribed for the first month. But people with coronary artery disease also have a long-term risk of developing clots, which can cause heart attacks or strokes.

For this reason, heart-disease patients are advised to take an aspirin tablet daily because it is an anticoagulant — it reduces the risk of blood clotting. The study presented here, called CREDO, is the first to look at whether there is a benefit in using a second anticoagulant, clopidogrel, for as long as a year.

One reason that clopidogrel is not used for longer periods may be the cost, which averages nearly $3 a day for a typical patient. Aspirin, on the other hand, is cheap and produces well-documented benefits. A June 2002 article in the New England Journal of Medicine concluded that wider use of clopidogrel will not be cost-effective unless the price comes down substantially.

In the CREDO study, patients were randomly assigned to one of two groups. The first group got a dose of clopidogrel before angioplasty and then continued taking it for a year afterward. The second group did not take clopidogrel before angioplasty. They were given clopidogrel for the first month and then a placebo pill afterward. Everyone received daily aspirin.

About 8.5 percent of the clopidogrel group died or had a stroke or heart attack during the follow-up period, compared with 11 percent of the aspirin-only group, said lead author Stephen R. Steinhubl, M.D., a University of North Carolina cardiologist. This is a risk reduction of 27 percent.

Researchers also were hoping to show that the pre-procedure dose of clopidogrel reduced death and complications in the first month. Although the rate was 18.5 percent lower for the group that got the advance dose, this difference was small enough that it could have been caused by chance.

One limitation of the study is that about 40 percent of the participants in both groups stopped taking their medicines, but the authors say that, if anything, this resulted in an underestimate of the potential benefits of clopidogrel.