Guidelines and Performance Measures for the Management of Acute Coronary Syndrome

BACKGROUND: Acute coronary syndrome (ACS) is caused by reduced perfusion of the myocardium and characterized by chest pain. The primary goals of treatment for ACS are to restore blood flow through occluded coronary arteries and prevent recurrent coronary events. Antiplatelet and anticoagulant therapies play a crucial role in the treatment of ACS by interrupting the thrombotic process. OBJECTIVES: To characterize the pathophysiology of ACS and to describe the American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for reperfusion therapy in patients with ST-segment elevation myocardial infarction (STEMI); the use of antiplatelet and anticoagulant therapies for the treatment of STEMI, non-ST-segment elevation myocardial infarction (NSTEMI), and unstable angina (UA), including patients who undergo percutaneous coronary intervention (PCI); and long-term antiplatelet therapy after an ACS episode. SUMMARY: The preferred reperfusion strategy in patients with STEMI is PCI if it can be performed within 90 minutes after arrival at the hospital. Patients with NSTEMI or UA also may undergo PCI. Thrombolysis is an alternative method of reperfusion for patients with STEMI but not for patients with NSTEMI or UA. Dual antiplatelet therapy with aspirin and the thienopyridine clopidogrel is recommended by the ACC/AHA for 12 months in patients with STEMI, NSTEMI, or UA, including patients with coronary stents. Platelet glycoprotein (GP) IIb/IIIa inhibitors are routinely used during PCI in patients with STEMI and NSTEMI. These agents should be used in addition to aspirin and clopidogrel in patients with NSTEMI and elevated troponin levels who undergo coronary intervention. Unfractionated heparin (UFH) or the low-molecular-weight heparin enoxaparin may be used in patients with STEMI undergoing reperfusion with thrombolytic agents or PCI and patients with NSTEMI or UA. There are substantial data on enoxaparin in the ACS arena, but UFH is preferred for patients who undergo coronary intervention because of greater ease of therapeutic monitoring and reversal of anticoagulant effects if bleeding complications arise. The pentasaccharide fondaparinux may become an alternative to UFH and enoxaparin for patients with STEMI and some patients with NSTEMI or UA. Fondaparinux is preferred for patients with NSTEMI or UA who are at increased risk for bleeding when a conservative approach is chosen, but it is not recommended for patients when an early invasive approach is chosen because of the risk of catheter-related thrombi. The direct thrombin inhibitor bivalirudin may be used for anticoagulation in patients with NSTEMI who undergo early invasive procedures, and GP IIb/IIIa inhibitor use may be avoided in some patients; however, upstream antiplatelet therapy with clopidogrel is also needed if these patients undergo PCI. Patients undergoing coronary stenting must receive dual antiplatelet therapy. CONCLUSIONS: Antiplatelet and anticoagulant therapies for patients with ACS are complex. Evidence-based guidelines facilitate the therapeutic decision-making process for these therapies in patients with ACS.