World's largest study on acute coronary syndromes

Sep 5 2005

A Canadian-led study involving researchers from 41 countries has demonstrated in the world's largest study of acute coronary syndromes (ACS) that a new anti-thrombotic therapy is safer and as effective as the traditional therapy used in preventing heart attacks, death and ischemia in people with serious heart conditions.

The OASIS-5/MICHELANGELO study, presented at the European Society of Cardiology meeting in Stockholm, Sweden, showed that fondaparinux, a new anti-thrombotic therapy, was as effective as enoxaparin in preventing heart attacks, death and ischemia (reduction in blood supply to the tissues) at nine days after an event but demonstrated a dramatic reduction in major bleeding. The study indicated patients had a lower mortality rate at the one-month mark after an acute coronary event. This finding remained consistent throughout the following six months of follow-up.

These favourable effects resulted in a clear net benefit in favour of fondaparinux throughout the study, said Dr. Salim Yusuf, principal investigator and chair of the international study.

"The study findings demonstrate that fondaparinux is likely the anti-thrombotic drug of choice in patients with acute coronary syndromes who are already receiving aspirin and clopidogrel," said Dr. Yusuf, professor of medicine in the Michael G. DeGroote School of Medicine at McMaster University and director of the Population Health Research Institute, McMaster University and Hamilton Health Sciences in Hamilton, Ontario, Canada. "This is the first study in ACS patients that demonstrates that effective prevention of thrombotic events can be combined with a safer drug profile."

The OASIS-5/MICHELANGELO study was a multi-centre, randomized, double-blind, placebo-controlled trial involving more than 20,000 patients and was conducted at 576 sites in 41 countries. The primary objective was to evaluate the efficacy and safety of fondaparinux, a synthetic drug that acts specifically during the earlier part of the clotting cascade, with enoxaparin, a low molecular weight heparin that is commonly used as an anti-thrombotic therapy.

Previous studies have indicated that patients who experience a major bleed in acute coronary syndromes exhibit a much higher risk of death during the immediate weeks following the event. Anti-thrombotic therapies used in the last two decades have substantially decreased the risk of a heart attack but have also been associated with a significant increase in bleeding risks. Therefore, therapies that maintain the benefits of currently available anti-thrombotic therapies, but have less bleeding, are of great clinical importance, Dr. Yusuf said.

Dr. Shamir R. Mehta, project director of the international study, associate professor of medicine in the Michael G. DeGroote School of Medicine at McMaster University and an interventional cardiologist at Hamilton Health Sciences, remarked: "The fact that the benefits and safety of fondaparinux are observed on top of other effective treatments, such as aspirin, clopidogrel, GP IIb/IIIa inhibitors and revascularization procedures, emphasizes its value in a broad spectrum of patients with acute coronary syndromes."

Dr. Mehta added: "One of the most important findings of the trial was that fondaparinux was associated with a lower overall mortality at six months compared with enoxaparin. This is good news for patients in that doctors now have a therapy that will not only saves lives but is also substantially safer than current treatments."

Professor Keith Fox, professor of cardiology at the University of Edinburgh and co-chair of the study's operation committee, added: "This study demonstrates that improving the safety of therapy leads to enhanced long-term survival for patients."

Dr. Yusuf noted that previous studies showed that fondaparinux was superior in preventing deep venous thrombosis when compared to enoxaparin. "The current findings extend the beneficial results from the venous side to high-risk individuals with atherothrombosis," he added.

The OASIS-5/MICHELANGELO study was supported by grants from Sanofi-Synthelabo, Organon, and Glaxo-Smith Kline. The OASIS network is led by researchers in the Population Health Research Institute, 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.

The Canadian Cardiovascular Collaboration Office is located at the Population Health Research Institute, McMaster University and Hamilton Health Sciences and is one of Canada's leading research institutions. The experts at this institution are recognized internationally for their leading edge research, innovation, and excellence in cardiovascular sciences and thrombosis.