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Anti-Clotting Drugs May Improve Heart Attack Care

Arixtra and Lovenox extend survival, lower post-attack events, studies show

TUESDAY, March 14, 2006 (HealthDay News) -- Two anti-clotting drugs improved survival and reduced the risk of cardiovascular trouble when given in the hours after a heart attack.

Those findings appear in reports presented Tuesday at the American College of Cardiology annual meeting, in Atlanta.

The reports, by two different teams of researchers, set up a potential duel over which of these two drugs -- Arixtra or Lovenox -- does the most good with the least incidence of excess bleeding.

The new data is "good news for patients who have heart attacks and doctors who take care of patients who have heart attacks," said researcher Dr. Elliott M. Antman, professor of medicine at Brigham and Women's Hospital in Boston and Harvard Medical School. He headed up one of the studies, focused on Lovenox.

Up till now, it has been standard practice to give patients aspirin, a clot-dissolving drug and the anti-clotting drug heparin in the hours and days after a heart attack, Antman noted.

In his team's trial, the drug Lovenox (enoxaparin) -- usually prescribed to prevent deep-vein clotting -- was substituted for heparin for half of the more than 20,000 heart-attack patients in the study.

According to Antman, Lovenox "reduced the chance of dying or having a second heart attack, which is highly significant. There was a 33 percent reduction in the chance of a second heart attack in the first 48 hours."

To put it another way, he said, "for every thousand patients who receive this clot-busting treatment, there will be 15 fewer nonfatal heart attacks, seven less bypass surgeries, six fewer deaths and four more nonfatal major bleeds."

Antman said this "small, statistically significant increase in severe bleeding episodes" was a price worth paying, since there was no increase in fatalities caused by those episodes.

The study results will also be published in the April 6 issue of the New England Journal of Medicine.

Antman's assessment was challenged by researchers investigating a rival anti-clotting drug, Arixtra (fondaparinux). They presented the results of two trials -- one comparing Arixtra to standard therapy, and a second head-to-head comparison of Arixtra vs. Lovenox.

The results, from a group led by physicians at McMaster University in Canada, will appear in the April 5 issue of the Journal of the American Medical Association, but are being released Tuesday to coincide with their publication at the Atlanta conference.

The trial involved more than 12,000 heart-attack patients treated at 447 hospitals around the world.

The Canadian-led team found an overall 14 percent reduction of death or second heart attack one month after heart attack for patients given Arixtra compared to those given standard care.

The results "confirm the value and safety" of the drug "in a broad group of patients with acute coronary syndrome," the researchers wrote.

But Antman said the results should be approached cautiously, because some of the patients in that trial were given a placebo, an inactive substance, rather than heparin. Proof of Arixtra's effectiveness requires a direct comparison with heparin treatment, he said.

Dr. James Velianou, associate professor of medicine at McMaster and a member of the research team, said the patients in the study were given "the standard of care at the time the study was done."

The Arixtra group also challenged Lovenox head-on in a paper that will also appear in the April 6 New England Journal of Medicine.

That paper compared the results of treatment with the two drugs in a trial of more than 20,000 patients who did not have the kind of heart attack of those in the two other studies, but had severe coronary problems.

The results, in terms of major problems -- including death, a heart attack or major artery blockage within nine days -- were similar for both drugs: 5.8 percent for Arixtra, 5.7 percent for Lovenox. But otherwise, the head-to-head study favored Arixtra: The number of severe bleeding episodes was substantially lower in the Arixtra group -- 2.2 percent versus 4.1 percent for Lovenox -- and Arixtra treatment "was associated with a significantly reduced number of deaths at 30 days."

The reduction in bleeding episodes is important, because "bleeding leads to extra problems," Velianou said. "People who bleed less tend to die less."

In a commentary in the Journal of the American Medical Association, Dr. Robert C. Califf, of Duke Clinical Research Institute, said the McMaster results "are sure to lead to an outburst of competitive pronouncements by companies and by leaders in the clinical community about the question of which regimen is truly best."

The answer, Califf said, probably will come from a combination of further clinical trials and lessons learned from experience with the treatments.

"We don't have that answer yet because that study hasn't been done," Velainou said.

More information

For more on the warning signs and treatment of heart attack, head to the American Heart Association.

SOURCES: Elliott M. Antman, professor, medicine, Harvard Medical School and Brigham and Women's Hospital, Boston; James Velianou, associate professor, medicine, McMaster University, Hamilton, Canada; March 13, 2006, American College of Cardiology annual meeting, Atlanta; April 5, 2006, Journal of the American Medical Association; April 6, 2006, New England Journal of Medicine
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