Anticoagulants in STEMI

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Heparin

• Mechanism of Action:
  • Binds to antithrombin III, converts to an active form, and inhibits thrombin and factor Xa
• Dosing & Administration:
  • IV 50- to 70-U/kg then infusion based on reperfusion plan
• Adverse Effects:
  • Bleeding & thrombocytopenia
• Contraindications:
  • Severe thrombocytopenia & active bleeding
• Clinical Pearls & Practical Considerations:
  • Heparin has a short half-life and its effect can be rapidly reversed by protamine sulfate.
  • Heparin can also cause heparin-induced thrombocytopenia (HIT), an immune-mediated reaction that can lead to thrombosis. HIT can occur 5 to 10 days after initiation of heparin therapy.
  • Monitoring: aPTT, INR, CBC, platelet count

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LMWH

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Bivalirudin

• Mechanism of Action:
  • Binds to thrombin, preventing thrombin-mediated platelet activation and thrombus formation
• Dosing & Administration:
  • 0.75 mg/kg IV bolus followed by infusion of 1.75 mg/kg/hr
  • Reduce infusion to 1 mg/kg/h with estimated CrCl <30 mL/min
• Adverse Effects:
  • Bleeding, Hypotension, Nausea, & Anaphylaxis
• PK/PD
  • Plasma half-life of 30 minutes; metabolized by liver
• Clinical Pearls & Practical Considerations:
  • It is often used as an alternative to heparin plus GPIIb/IIIa inhibitors in patients with high bleeding risk.
  • May be preferred in those with high risk of bleeding
  • There is no specific reversal agent for bivalirudin

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Anticoagulant Drug Chart

Drug	Mechanism of Action	Dosage and Route of Administration	Onset of Action	Elimination Half-life	Adverse Effects
Heparin	Indirect thrombin	50-70 unit IV bolus, followed by continuous infusion	Immediate	1-2 hours	Bleeding, HIT, thrombocytopenia, hypersensitivity, hyperkalemia, osteoporosis
Enoxaparin	Indirect Factor Xa	1 mg/kg Subcutaneous	3-5 hours	4-7 hours	Bleeding, thrombocytopenia, HIT, hyperkalemia, hypersensitivity, osteoporosis
Bivalirudin	Direct thrombin	0.75 mg/kg IV bolus followed by infusion of 1.75 mg/kg/hr	Immediate	25 minutes	Bleeding, anemia, hypotension, thrombocytopenia, angina, dyspnea, allergic reaction
Fondaparinux	Indirect Factor Xa	Subcutaneous	3 hours	17-21 hours	Bleeding, thrombocytopenia, anemia, injection site reaction, hypersensitivity, caution in renal impairment

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AHA STEMI Guidelines- Anticoagulants Prior to PCI

Drug	Recommendation	LOE	COE
UFH	•With GP IIb/IIIa receptor antagonist planned: 50- to 70-U/kg IV bolus to achieve therapeutic ACT of 200 to 250 s. •GP IIb/IIIa receptor antagonist planned: 70- to 100-U/kg bolus to achieve therapeutic ACT is 250 to 300 s (HemoTec device) or 300 to 350 s (Hemochron device).	I	C
Bivalirudin	0.75-mg/kg IV bolus, then 1.75-mg/kg/h infusion with or without prior treatment with UFH. •An additional bolus of 0.3 mg/kg can be given if needed. •Reduce infusion to 1 mg/kg/h with estimated CrCl <30 mL/min	IIa	B
	Preferred over UFH with GP IIb/IIIa receptor antagonist in patients at high risk of bleeding	IIa	B
Fondaparinux	Not recommended as sole anticoagulant for primary PCI	III	Harm B