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Fondaparinux: Benefits in STEMI and NSTEMI

Fondaparinux showed benefits over other antithrombotic regimens in acute coronary syndrome patients, except those who underwent primary PCI.

Fondaparinux (Arixtra), a synthetic factor Xa inhibitor, has outperformed the low-molecular-weight heparin enoxaparin in preventing venous thromboembolism after orthopedic surgery (Journal Watch Cardiology Aug 9 2002). In two new manufacturer-funded, multinational, randomized controlled trials, researchers tested fondaparinux in patients with coronary thrombosis.

In the OASIS-5 trial, 20,078 patients (mean age, 67) with unstable angina or non–ST-segment-elevation MI (UA/NSTEMI) were randomly assigned to receive single-dose fondaparinux (2.5 mg daily) or enoxaparin (1 mg/kg twice daily). Mean treatment duration was 6 days. At 9 days, incidence of the primary outcome — death, MI, or refractory ischemia — was similar with fondaparinux (5.8%) and enoxaparin (5.7%), but the incidence of major bleeding was significantly lower with fondaparinux (2.2% vs. 4.1%). Fondaparinux recipients also had significantly lower mortality rates at 30 days (2.9% vs. 3.5%) and at 6 months (5.8% vs. 6.5%).

In the OASIS-6 trial, 12,092 patients (mean age, 62) with ST-segment-elevation MI (STEMI) were randomized to receive fondaparinux (2.5 mg daily) or usual care for up to 8 days. Usual care was unfractionated heparin (UFH) for up to 48 hours followed by placebo, or just placebo when UFH was not indicated. Of the entire cohort, 45% received fibrinolysis (usually streptokinase), 29% primary PCI, and 24% no reperfusion therapy. The incidence of death or reinfarction at 30 days was significantly lower with fondaparinux than with usual care (9.7% vs. 11.2%), with significant benefits also at 9 days and at final follow-up (3–6 months). Fondaparinux recipients also had significantly lower mortality rates throughout the study and a trend toward less major bleeding. Notably, the benefits of fondaparinux did not extend specifically to patients who underwent primary PCI, and the drug was associated with significantly more catheter thromboses in this subgroup (1.2% vs. 0%).

Comment: These large randomized trials show an advantage of a simple fondaparinux regimen over other antithrombotic regimens in acute coronary syndrome patients, with or without STEMI, among subjects not intended for primary PCI. Fondaparinux is safe and relatively inexpensive, does not require routine monitoring, and is likely to be favored in settings without routine mechanical coronary reperfusion. However, fondaparinux is not yet FDA-approved for treating patients with coronary thrombosis.

— Beat J. Meyer, MD

Published in Journal Watch Cardiology April 6, 2006

Citation(s):

The Fifth Organization to Assess Strategies in Acute Ischemic Syndromes Investigators. Comparison of fondaparinux and enoxaparin in acute coronary syndromes. N Engl J Med 2006 Apr 6; 354:1464-76.

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• Medline abstract (Free)

The OASIS-6 Trial Group. Effects of fondaparinux on mortality and reinfarction in patients with acute ST-segment elevation myocardial infarction: The OASIS-6 Randomized Trial. JAMA 2006 Apr 5; 295:1519-30.

• Original article (Subscription may be required)
• Medline abstract (Free)

Califf RM. Fondaparinux in ST-segment elevation myocardial infarction: The drug, the strategy, the environment, or all of the above. JAMA 2006 Apr 5; 295:1579-80.

• Original article (Subscription may be required)
• Medline abstract (Free)