The term “acute coronary syndrome” (ACS) refers to the constellation of symptoms manifesting as a result of acute myocardial ischemia. ACS encompasses unstable angina, NSTEMI and STEMI. The guidelines described and discussed here are limited to unstable angina/NSTEMI. Anticoagulant therapy for ACS includes unfractionated heparin, low-molecular heparin (enoxaparin), hirudin, fondaparinux (an indirect inhibitor of factor Xa) and bivalirudin (a direct anti-IIa anticoagulant). The 2007 updated ACC/AHA guidelines give unfractionated heparin/ enoxaparin a I-A recommendation, whether in early invasive strategy or selectively invasive strategy-managed patients. The guidelines recommend fondaparinux at a I-B level, with particular emphasis on choosing it for patients at increased risk for bleeding (female, elder, anemic and diminished renal function), but needs an additional anticoagulant with antithrombin activity at percutaneous coronary intervention (PCI). Bivalirudin can be used in the patient undergoing an early invasive strategy (I-B), and when given with a clopidogrel loading dose at least 6 hours before catheterization without GP IIb/IIIa inhibitor(IIa-B).
Antiplatelet therapy for ACS includes aspirin, clopidognel and GP IIb/IIIa inhibitor. Dual antiplatelet therapy (aspirin and clopidogrel) should be given as soon as possible after even potential ACS is recognized except coronary artery bypass graft is planned within 5-7 days. Small-molecule GP IIb/IIIa inhibitor therapy is reversible and offers ischemic protection when platelets are already activated but is also associated with bleeding risk, although this can be minimized with proper dosing based on weight and estimated creatinine clearance. |
