[img_inline align=”right” src=”http://padnws01.mcmaster.ca/images/yusuf_mehta.jpg” caption=”Salim Yusuf and Shamir Mehta (left to right).”]A landmark Canadian-led study involving researchers from 41 countries has found that a simple anti-blood-clotting drug significantly reduces death and repeat heart attacks, without increasing the risk of bleeding.

The OASIS-6 randomized trial, presented at the American College of Cardiology meeting in Atlanta, U.S. today, showed that in patients experiencing a major heart attack fondaparinux (ArixtraTM), a novel antithrombotic therapy, was effective at lowering death and repeat heart attacks without increasing the risk of bleeding. This effect is unique as, until now, all available antithrombotic drugs used for the treatments of heart attacks have increased bleeding.

Patients in the study were receiving aspirin, other antiplatelet drugs (such as clopidogrel) or clot dissolving (thrombolytic therapy) treatments. All benefited. However, some patients who also underwent angioplasty as initial treatment for their heart attacks did not.

The four-year study involving more than 12,000 patients showed that the risk of deaths and heart attacks were reduced by one-sixth. This means that treating 1,000 patients for eight days would prevent about 15 to 20 individuals from suffering a new heart attack or dying.

The study was presented today at the scientific sessions of the American College of Cardiology in Atlanta by Dr. Salim Yusuf and Dr. Shamir Mehta. The study will be posted online in the Journal of the American Medical Association this week.

Yusuf is a professor of medicine at the Michael G. DeGroote School of Medicine at McMaster University, director of the Population Health Research Institute and holds an endowed chair of the Heart and Stroke Foundation of Ontario. Mehta is an associate professor of medicine at the Michael G. DeGroote School of Medicine, a member of the Population Health Research Institute and a clinical scientist with the Canadian Institutes of Health Research.

“These results are close on the heels of the OASIS-5 study that demonstrated the benefits of fondaparinux compared to enoxaparin, which is commonly used in patients with non-ST elevation MI,” Yusuf said. These results were presented last September at the European Society of Cardiology in Stockholm and are published this week online in The New England Journal of Medicine.

“The results of the two trials together clearly establish fondaparinux as an attractive therapeutic option in a broad range of high risk patients with heart attacks or unstable angina,” said Yusuf.

“The lack of excess bleeding in these extensive studies is remarkable and unique among antithrombotic agents,” Mehta said. “We have finally found a treatment that saves lives but does not increase bleeding. This is important for all patients, but especially in the frail and the elderly.” Mehta noted that previous studies showed that fondaparinux was effective in preventing blood clots after major orthopedic surgery and now the OASIS-5 and OASIS-6 studies have established the superiority of fondaparinux as an effective anticlotting agent in multiple conditions.

The OASIS-5/MICHELANGELO study was supported by grants from Sanofi-Synthelabo, Organon, and GlaxoSmithKline. The OASIS network is led by researchers in the Population Health Research Institute at McMaster University and Hamilton Health Sciences and is an international collaboration of investigators who have completed some of the largest and most influential trials in heart disease that have contributed to enhanced patient care worldwide.