What is the recommended dose and duration of Enoxaparin (low molecular weight heparin) for the management of Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Enoxaparin Dosing and Duration for NSTEMI

For NSTEMI, administer enoxaparin 1 mg/kg subcutaneously every 12 hours, continued for the duration of hospitalization or until PCI is performed. 1

Standard Dosing Regimen

• Dose: 1 mg/kg subcutaneously every 12 hours 1
• Optional IV loading dose: An initial 30 mg intravenous bolus has been used in selected patients, though this is not universally required for NSTEMI 1
• Duration: Continue throughout hospitalization or until PCI is performed 1

Critical Dose Adjustments

Renal Impairment

• For creatinine clearance <30 mL/min: Reduce dose to 1 mg/kg subcutaneously once daily (not every 12 hours) 1
• Calculate creatinine clearance in all patients before initiating enoxaparin, as renal impairment is common in older patients and significantly affects dosing 1
• Consider switching to UFH as an alternative in severe renal dysfunction 1

Management at Time of PCI

The timing of the last enoxaparin dose relative to PCI determines additional anticoagulation needs:

• If PCI occurs within 8 hours of last subcutaneous dose: Generally adequate anticoagulation exists; no additional enoxaparin needed 1
• If PCI occurs 8-12 hours after last dose: Administer additional 0.3 mg/kg IV enoxaparin at time of PCI 1
• If PCI occurs >12 hours after last dose: Treat as de novo anticoagulation with full-dose regimen 1

Critical Safety Considerations

Avoid "Stacking" Anticoagulants

• Never administer UFH to patients already on enoxaparin during PCI—this "stacking" significantly increases bleeding risk 1
• The SYNERGY trial demonstrated increased bleeding complications when patients on upstream enoxaparin received additional UFH at PCI 1

Bleeding Risk Profile

• Enoxaparin demonstrates superior efficacy compared to UFH in reducing recurrent ischemic events in NSTEMI 1
• The ESSENCE trial showed sustained benefit at 1 year with reduced recurrent ischemia and need for invasive procedures 1
• While some studies showed slightly increased TIMI major bleeding with enoxaparin versus UFH, this was often related to improper "stacking" of anticoagulants 1

Evidence Quality

This recommendation carries Level of Evidence A from the 2014 ACC/AHA guidelines for NSTEMI management 1. The guidelines give enoxaparin a Class I recommendation, meaning it is definitively indicated for all NSTEMI patients requiring anticoagulation, regardless of whether an early invasive or ischemia-guided strategy is planned 1.

Common Pitfalls to Avoid

• Failing to dose-adjust for renal function: Always calculate creatinine clearance before initiating therapy 1
• Adding UFH during PCI: This increases bleeding without improving outcomes 1
• Confusing NSTEMI dosing with STEMI dosing: STEMI protocols may include mandatory IV bolus and different timing; NSTEMI does not require the IV bolus 2
• Continuing enoxaparin beyond hospitalization without clear indication: Duration is until discharge or PCI, not indefinite 1