Benefits and Risks of Anticoagulation in Acute Coronary Syndrome

BACKGROUND: Both antiplatelets and anticoagulants are necessary in the management of acute coronary syndrome (ACS), although the exact proportion of antithrombotic effect that each drug and class should ideally provide remains a matter of ongoing study. AREA OF UNCERTAINTY: Defining the best combination between the antiplatelet agents and oral anticoagulants (OACs) can be challenging. The choice is particularly important for special categories of patients with ACS who have an indication of a long-term OAC. DATA SOURCES: A literature search regarding benefits and risks of anticoagulation in ACS was conducted through MEDLINE and EMBASE (past 20 years until September 2018). THERAPEUTIC ADVANCES: Many patients with ACS have an indication for long-term OACs. Those receiving dual antiplatelet therapy and anticoagulants are considered to be at a high bleeding risk. The addition of a vitamin K antagonist (VKA) imposes a target international normalized ratio of 2.0-3.0. When non-VKA oral anticoagulants are used, the lowest effective tested dose for stroke prevention should be applied. For most patients, triple therapy in the form of an OAC plus dual antiplatelet therapy [aspirin and P2Y12 inhibitors (usually clopidogrel)] should be considered for 3-6 months. Later, dual therapy (OAC plus aspirin or clopidogrel) should be considered for an additional 6 months. After 1 year, it is recommended that only the OAC is maintained. In cases of very high bleeding risk, triple therapy can be reduced to 1 month after ACS, continuing on dual therapy up to 1 year, and thereafter only anticoagulation. In general, the bleeding risk seems to be lower with non-VKA oral anticoagulants than VKA plus antiplatelet combination. CONCLUSIONS: Many risk factors for ischemic events and bleeding overlap. The clinician's challenges include monitoring patients' adherence and global assessment of the antithrombotic effect that incorporates antiplatelet and anticoagulant effects.