New Blood Thinner May Reduce Bleeding Risks

Sept. 5, 2005 (Stockholm, Sweden) -- A newer, more selective blood thinner is safer, cheaper, and just as effective as the standard treatment used during a heart attack or to treat an impending one, according to a new study.

When a heart attack occurs, the coronary arteries are blocked and heart muscle is deprived of oxygen.

Clot busters dissolve a clot in a coronary artery and restore blood flow. Blood thinners don't dissolve clots but prevent new clots from forming. They are given to help prevent further damage to dying heart muscles and to help restore their function. However, bleeding can be a complication of blood thinners.

The newer drug, known as Arixtra, could reduce by 80% the risk of dying due to serious bleeding, the major risk of blood thinners, says researcher Salim Yusuf, MD, chief of cardiology at McMaster University in Hamilton, Ontario.

The study pitted Arixtra against the traditional blood thinner Lovenox in 20,000 people with what doctors call acute coronary syndrome -- chest pain caused by a blocked heart artery that can cause a heart attack.

For every 1,000 people given Arixtra instead of Lovenox, 10 deaths or heart attacks, four strokes, and 25 major bleeds will be prevented, Yusuf tells WebMD.

"These are the people who, if not treated effectively, will die or suffer life-altering consequences," says American Heart Association spokesman Timothy Gardner, MD. Gardner is a heart surgeon at the University of Pennsylvania in Philadelphia who was not involved with the research.

The findings were presented at the annual meeting of the European Society of Cardiology.

Researchers showed that the two blood thinners were equally effective at preventing heart attacks and deaths in the first 10 days after treatment.

But only 2% of those treated with Arixtra had major bleeding complications compared with 4% of those treated with Lovenox. That meant fewer transfusions to replace blood loss.

Thirty days after the treatment, there were 17% fewer deaths in those treated with Arixtra than in the other treatment group.

Arixtra Works Earlier in Clotting Cascade

One of the reasons the newer medication may have the edge is its novel mode of action, the researchers say.

Clots are formed through a cascade of events. Arixtra appears to work at an earlier step in the formation of a clot.

Arixtra inhibits a protein critical to clot formation. In contrast, Lovenox works by combining with a protein in blood to prevent other proteins from working together to form a clot.

Gardner says the newer drug "could have a tremendous impact" on the treatment of people with acute coronary syndrome.

"It's a new type of drug in that it affects the clotting cascade earlier and doesn't have the side effects" of the older medication, he tells WebMD. Nevertheless, he says further studies are needed to confirm the results before he would make the switch.