The safety and effectiveness of fondaparinux for heart attacks

The results of a large international cardiovascular trial will shed light on whether the addition of a new drug that prevents blood clotting, or thrombosis, can improve the treatment of the most serious form of heart attacks.

The research was presented at the American College of Cardiology's 55th Annual Scientific Session and the inaugural Innovation in Intervention: i2 Summit 2006 in Atlanta, Ga.

"In people with heart attacks, we don't yet know whether antithrombotic agents add to the benefit of existing therapies," said Salim Yusuf, M.D., a professor of medicine and director of the Population Health Research Institute at McMaster University, Hamilton, Ontario, Canada. "The OASIS-6 trial will answer that question."

The OASIS-6 trial evaluated the safety and effectiveness of fondaparinux. This antithrombotic drug inhibits factor Xa, a blood protein that intensifies blood clot formation by activating a complex coagulation cascade and generating thrombin. Fondaparinux has previously proved effective in patients with blood clots in the veins of the leg and in patients with acute coronary syndrome.

"Fondaparinux prevents amplification of the coagulation system. By blocking one factor Xa molecule, you can block the production of 50 thrombin molecules," Dr. Yusuf said.

More than 12,000 patients participated in the OASIS-6 study. All had ST elevation myocardial infarction (STEMI), a serious form of heart attack that derives its name from the elevation of the "ST segment" on the electrocardiogram. In some cases, the primary treatment for heart attack was clot-busting medication and in other cases, it was catheter-based therapy.

Investigators randomly assigned patients to add-on therapy with fondaparinux or placebo, adjusting the dose and treatment plan to take into account other blood thinning medications the patient's physician routinely used, such as glycoprotein IIb/IIIa inhibitors or unfractionated heparin. The trial will determine whether fondaparinux reduced the risk of death or repeat MI within 30 days, while avoiding excessive bleeding complications.

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