Studies show enoxaparin an effective alternative to heparin for acute coronary syndromes


Two new major studies suggest that anticoagulant therapy with enoxaparin is an effective alternative to heparin therapy for patients with acute coronary syndromes (ACS), according to articles in the July 7 issue of The Journal of the American Medical Association (JAMA).

In the first study, investigators with the Superior Yield of the New Strategy of Enoxaparin, Revascularization and Glycoprotein IIb/IIIa inhibitors (SYNERGY) trial compared the outcomes of patients treated with enoxaparin vs. unfractionated heparin. Although previous trials have demonstrated the superiority of enoxaparin compared with unfractionated heparin for patients with non–ST-elevation (a certain pattern on the electrocardiogram) ACS receiving medical therapy as their primary treatment strategy, the value of enoxaparin as the principal anticoagulant regimen for ACS has been debated.

The SYNERGY trial was a randomized, multicenter, international trial conducted between August 2001 and December 2003. A total of 10,027 high-risk patients with non–ST-elevation ACS to be treated with an intended early invasive strategy were recruited. Participants received either subcutaneous enoxaparin (n=4,993) or intravenous unfractionated heparin (n=4,985), administered immediately after enrollment and continued until the patient required no further anticoagulation, as judged by the treating physician. The primary efficacy outcome was the composite clinical end point of death or nonfatal myocardial infarction (MI, heart attack) during the first 30 days after randomization. The primary safety outcome was major bleeding or stroke.

The researchers found that the primary end point of death or nonfatal MI by 30 days occurred in 14.0 percent of patients assigned to enoxaparin and 14.5 percent of patients assigned to unfractionated heparin. Enoxaparin was not superior to unfractionated heparin but fulfilled the noninferiority criteria. "No differences in ischemic events reported by the physician during percutaneous coronary intervention [PCI, i.e., a stent] were observed between enoxaparin and unfractionated heparin, including similar rates of abrupt closure, threatened abrupt closure, unsuccessful PCI, or emergency coronary artery bypass graft [CABG] surgery. Bleeding was modestly increased in patients assigned to enoxaparin …," the researchers write.

"In high-risk patients with an intended early invasive treatment strategy, enoxaparin and unfractionated heparin are safe and effective alternatives as the antithrombin regimen. Enoxaparin has the advantages of convenience (fixed dosing without need for monitoring or intravenous infusion) and a trend toward a lower rate of nonfatal MI with a modest excess of bleeding. As a first-line agent in the absence of changing antithrombin therapy during treatment, enoxaparin appears to be superior without an increased bleeding risk," the authors write.

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Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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