What is the role of enoxaparin (low molecular weight heparin) in the management of acute ischemic stroke?

Role of Enoxaparin in Ischemic Stroke

Enoxaparin's primary role in acute ischemic stroke is for venous thromboembolism (VTE) prophylaxis in high-risk patients, not for treatment of the stroke itself or prevention of stroke recurrence. 1

VTE Prophylaxis in Ischemic Stroke

Indications for Enoxaparin

• Patients at high risk for developing VTE:
  • Unable to move one or both lower limbs
  • Unable to mobilize independently
  • Previous history of venous thromboembolism
  • Dehydration
  • Comorbidities such as cancer 1

Timing and Dosing

• Start within 48 hours of stroke onset if no contraindications exist 1
• Standard prophylactic dose: 40 mg subcutaneously once daily 1, 2
• For patients with renal failure: Consider unfractionated heparin instead 1

Evidence of Efficacy

• The PREVAIL study demonstrated that enoxaparin 40 mg once daily was superior to unfractionated heparin (UFH) 5000 IU twice daily in preventing VTE:
  • 43% reduction in VTE risk with enoxaparin compared to UFH (10% vs 18%, p=0.0001)
  • Benefit consistent across stroke severity subgroups 2
  • Similar safety profile regarding intracranial hemorrhage (1% in both groups) 2

Duration of Therapy

• Typically administered for 10 days (range 6-14 days) 2
• For patients remaining immobile beyond 30 days, ongoing VTE prophylaxis should be considered 1

Alternative VTE Prevention Options

Intermittent Pneumatic Compression (IPC)

• Equally recommended as first-line option for VTE prophylaxis 1
• Should be applied within first 24 hours after admission
• Continue until patient becomes independently mobile, discharge, or 30 days (whichever comes first)
• Requires daily skin integrity assessment 1

Not Recommended

• Anti-embolism stockings alone are not recommended for post-stroke VTE prophylaxis 1

Important Caveats and Contraindications

Contraindications

• Systemic or intracranial hemorrhage 1
• Contraindicated during first 24 hours after intravenous thrombolysis (rtPA) 1

Safety Considerations

• While enoxaparin reduces VTE risk, it may slightly increase risk of extracranial hemorrhage compared to UFH 2
• A meta-analysis found that low-molecular-weight heparins may increase symptomatic intracerebral hemorrhage more than they reduce symptomatic pulmonary embolism 3

Neurological Outcomes

• PREVAIL subanalysis showed no difference in long-term neurological outcomes between enoxaparin and UFH groups 4
• Similar rates of stroke progression (5.1% vs 4.8%) and intracranial hemorrhage (2.3% vs 2.5%) between enoxaparin and UFH 4

Role in Stroke Treatment (Not Recommended)

Enoxaparin is not recommended for:

• Treatment of the acute ischemic stroke itself 1
• Prevention of early recurrent stroke 1
• Routine management of patients with ischemic stroke as an alternative to aspirin 1

Algorithm for VTE Prophylaxis in Ischemic Stroke

1. Assess VTE risk within 24 hours of admission
2. If high risk and no contraindications:
   • Choose either enoxaparin 40 mg SC daily OR intermittent pneumatic compression
   • For patients with renal failure: Use unfractionated heparin 5000 IU SC twice daily
3. Start prophylaxis within 48 hours of stroke onset
4. Continue for 10 days or until fully mobile
5. For patients immobile >30 days: Consider extended prophylaxis
6. Encourage early mobilization and adequate hydration for all patients

Remember that enoxaparin's evidence-based role in ischemic stroke is limited to VTE prophylaxis and not for treatment of the stroke itself or prevention of stroke recurrence.