Anticoagulation in Acute Coronary Syndrome

Rationale for Adding Anticoagulation to DAPT

The American Heart Association recommends anticoagulation for all ACS patients in addition to antiplatelet therapy, regardless of whether they are already on aspirin and clopidogrel, to reduce ischemic events 1, 3
The combination of antiplatelet agents (aspirin + clopidogrel) and heparin targets complementary mechanisms of thrombosis, reducing ischemic events 1
Premature discontinuation of anticoagulation is associated with a transient rebound increase in thrombin activity and reactivation of ischemic events, with the greatest risk for reinfarction occurring 4-8 hours after stopping anticoagulation 1
Historical data showed that aspirin plus heparin reduced MI or death compared to aspirin alone, although this was not statistically significant in older trials 1

The European Society of Cardiology recommends selecting anticoagulation based on both ischemic and bleeding risks, and according to the efficacy-safety profile of the chosen agent 3
Unfractionated heparin (UFH) is recommended as a standard option, with a loading dose of 60 IU/kg (maximum 4000 IU), followed by infusion of 12 IU/kg/h (maximum 1000 IU/h), adjusted to maintain aPTT 60-80 seconds 1, 4
Low-Molecular-Weight Heparin (Enoxaparin) is a reasonable alternative to UFH, with a dose of 1 mg/kg subcutaneous every 12 hours (reduce to 1 mg/kg daily if CrCl <30 mL/min) 1
Fondaparinux is a reasonable option for conservative management, but should not be used to support PCI due to increased risk of catheter thrombosis, with a dose of 2.5 mg subcutaneous daily (contraindicated if CrCl <30 mL/min) 1, 4
Bivalirudin may be considered as an alternative to UFH, particularly in patients with increased bleeding risk or renal insufficiency, with a dose of 0.75 mg/kg bolus, 1.75 mg/kg/h IV infusion during PCI 1, 2, 5

The American College of Cardiology recommends continuing parenteral anticoagulation until revascularization (PCI or CABG) is performed 1, 4
Parenteral anticoagulation should be discontinued immediately after the invasive procedure unless there is a compelling reason to continue 3, 4

The European Heart Journal recommends avoiding crossover between UFH and LMWH, as this increases bleeding risk without improving efficacy 3
Bleeding risk increases with concomitant fibrinolytic agents or GP IIb/IIIa inhibitors—adjust dosing accordingly 4
For patients with high bleeding risk, fondaparinux or bivalirudin are reasonable choices over UFH 5
Reduce enoxaparin to 1 mg/kg daily if CrCl <30 mL/min; fondaparinux is contraindicated at this level 1, 4