Mixed Results for Anti-Clotting Drugs in Heart Attacks

One therapy works, while another doesn't, studies find

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By
HealthDay Reporter

WEDNESDAY, May 21, 2008 (HealthDay News) -- Emergency treatment with two different anti-clotting drugs doesn't help much when someone who suffers a heart attack can't get a quick artery-opening procedure, new research shows.

On a brighter note, a third anti-clotting agent does improve results of such a procedure after a heart attack, another study finds.

Both studies, reported in the May 22 issue of the New England Journal of Medicine, are important for the 1.2 million Americans who have heart attacks each year. They are supposed to get what used to be called angioplasty and now goes by the formal medical name of percutaneous coronary intervention (PCI), in which a balloon-tipped catheter is threaded into a blocked artery, preferably within three hours of the attack.

That goal is hard to achieve in many cases, often because a hospital equipped for PCI isn't close enough. So cardiologists have been testing the value of two drugs -- reteplase, which dissolves clots, and abciximab, which prevents their formation -- for people who don't get PCI within the recommended time frame.

However, a study of 2,452 people whose treatment started as late as six hours after a heart attack found no value from the drug treatment.

Some people were given abciximab and reteplase well before PCI, some were given early abciximab, and some were given abciximab just before PCI. The incidence of major problems and death was about the same for all three methods -- 9.8 percent, 10.5 percent and 10.7 percent, respectively.

"Combination therapy, when given up front, did not offer any benefit in the primary endpoints of the study," said Dr. Jane A. Leopold, an assistant professor of medicine at Harvard Medical School, who wrote an accompanying editorial. "In fact, it led to an increase in bleeding. This study tells us that by giving these drugs to patients up front, we are not helping them."

The report probably will affect medical practice, Leopold indicated. "A number of interventional cardiologists have been awaiting results of this trial, because it was a definitive study of combination-facilitated PCI," she said.

The study shows that "the effort to use powerful antiplatelet drugs to make the outcome better for patients who have heart attacks should be abandoned," said study author Dr. Stephen G. Ellis, a professor of medicine at the Cleveland Clinic. Platelets are the blood cells that clump together to form blood clots.

"There might be a very modest benefit for high-risk patients in terms of the size of the heart attack, but it seems to be offset by the increase in bleeding risk," Ellis said. "Based on present information, it is difficult to advocate it for any patients."

However, a second report in the same journal said a study established the value of using a newer kind of anti-clotting drug, bivalirudin, during PCI after a heart attack.

The study of 3,602 people given PCI within 12 hours of a heart attack found that using bivalirudin rather than the older, established anti-clotting therapy reduced the incidence of major complications and death.

The overall death rate in the following 30 days for those given bivalirudin was 2.1 percent, compared to 3.1 percent for those given the older anti-clotting treatment.

"I would expect this to become the standard of care," said study author Dr. Gregg W. Stone, a professor of medicine at Columbia University in New York City. "This is the first study of bivalirudin to show a reduction of mortality in a large randomized trial. Whenever you save lives, it is a major finding."

Bivalirudin is safer, because "it avoids all major bleeding complications, which are directly related to mortality," Stone said.

More information

Learn more about percutaneous coronary intervention from the American Heart Association.

SOURCES: Jane A. Leopold, M.D., assistant professor, medicine, Harvard Medical School, Boston; Stephen G. Ellis, M.D., professor, medicine, Cleveland Clinic; Gregg W. Stone, M.D., professor, medicine, Columbia University, New York City; May 22, 2008, New England Journal of Medicine

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