2007 Guideline Update for Unstable Angina/Non–ST-Segment Elevation Myocardial Infarction: Focus on Antiplatelet and Anticoagulant Therapies

Abstract

Objective: To summarize key changes in the 2007 American College of Cardiology/American Heart Association (ACC/AHA) guideline recommendations for pharmacologic therapy as they relate to antiplatelets and anticoagulants, and to evaluate the evidence from several landmark trials that was used to support the guideline updates for these agents. Data Sources: Literature was accessed through MEDLINE (1950–January 2008) using the search terms acute coronary syndromes, unstable angina (UA), non–ST-segment elevation myocardial infarction (NSTEMI), antiplatelet, and anticoagulant. All papers were cross-referenced to identify additional studies, Study Selection and Data Extraction: ACC/AHA guidelines, relevant original research articles, and review articles were evaluated. Studies with more than 1000 patients were the focus of the review. Data Synthesis: UA and NSTEMI are the most common presentations of acute coronary syndrome. The recently updated ACC/AHA guidelines for management of this condition were based on significant advances in pharmacotherapy including expanded use of drug-eluting stents, pretreatment with Clopidogrel, and newer anticoagulants such as bivalirudin and fondaparinux. Landmark trials have been published that describe advances in the use of antiplatelets and anticoagulants. According to the guidelines, unfractionated heparin (UFH) and enoxaparin are preferred options for both invasive and conservative management. Enoxaparin was noninferior to UFH for invasive management in the SYNERGY trial, although it was associated with a higher incidence of bleeding. Other alternatives for an invasive strategy per the guidelines include bivalirudin and fondaparinux. Bivalirudin (alone or with glycoprotein [GPJ llb/llla inhibitor) was compared with heparin plus GP llb/llla inhibitor in the ACUfTY trial of patients undergoing early invasive management. The bivalirudin groups were noninferior to standard of care, although bivalirudin alone was associated with less bleeding. Fondaparinux was found to be noninferior to enoxaparin and was associated with fewer bleeding events in the OASIS-5 study of patients who were not treated with an early invasive approach. Accordingly, the guidelines list fondaparinux as an alternative for a conservative strategy or in patients at increased risk of bleeding. Conclusions: Clinicians should be familiar with the updated 2007 ACC/AHA guidelines and the clinical trial evidence that serves as the basis for these recommendations. It is paramount for institutions to outline a preferred and consistent treatment approach. These decisions should Involve a review of established efficacy, bleeding risk, need for anticoagulant reversal, costs, and clinician familiarity with different treatment regimens.