What is the dose of low molecular weight heparin (LMWH) for Non-ST-Elevation Myocardial Infarction (NSTEMI) and ST-Elevation Myocardial Infarction (STEMI)?

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Last updated: June 22, 2025View editorial policy

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From the Guidelines

For NSTEMI and STEMI, the recommended dose of low molecular weight heparin (LMWH) is typically enoxaparin 1 mg/kg subcutaneously every 12 hours, as supported by the most recent guidelines 1.

Key Considerations

  • In patients with STEMI undergoing primary percutaneous coronary intervention (PCI), an initial intravenous bolus of 0.5 mg/kg may be given, as indicated in the guidelines 1.
  • Dose adjustment is necessary for patients with renal impairment (creatinine clearance <30 mL/min), typically reducing to 1 mg/kg once daily, to minimize the risk of bleeding complications 1.
  • For elderly patients (≥75 years) with STEMI, the initial IV bolus is often omitted, and the subcutaneous dose reduced to 0.75 mg/kg every 12 hours, to reduce the risk of bleeding 1.

Treatment Duration and Monitoring

  • Treatment duration generally continues throughout hospitalization, typically 2-8 days, until revascularization or clinical stabilization, as recommended by the guidelines 1.
  • Regular monitoring of hemoglobin, platelet count, and renal function is important during treatment to assess for bleeding complications, as emphasized in the studies 1.

Other LMWH Options

  • Other LMWH options include dalteparin (120 IU/kg every 12 hours, maximum 10,000 IU per dose) and fondaparinux (2.5 mg subcutaneously once daily), though enoxaparin is most commonly used, as noted in the guidelines 1.
  • LMWH works by inhibiting factor Xa and thrombin, preventing clot extension and recurrent ischemic events, as explained in the studies 1.

From the Research

Dose of Low Molecular Weight Heparin (LMWH) for NSTEMI and STEMI

  • The dose of enoxaparin for patients with STEMI is an initial 30 mg intravenous bolus, followed by 1 mg/kg subcutaneously within 15 minutes and then every 12 hours for up to 8 days, with the first two subcutaneous dosages not to exceed 100 mg 2, 3.
  • For patients with NSTEMI, the dose of enoxaparin is 1 mg/kg subcutaneously every 12 hours for 2-8 days 4, 5.
  • The dose of fondaparinux for patients with ACS, including those with STEMI and NSTEMI, is 2.5 mg/day subcutaneously for up to 8 days 6.
  • Reduced-dose enoxaparin, with a median of 3 doses at a mean dose of 0.51 mg/kg, has been used in patients with NSTEMI, with the final dose administered 10.8 hours before PCI 4.
  • For patients aged 75 years or older, the dose of enoxaparin is reduced to 0.75 mg/kg every 12 hours, and for patients with an estimated creatinine clearance of less than 30 mL/min, the dose is reduced to 1 mg/kg every 24 hours 2, 3.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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