What is the appropriate use of enoxaparin (low molecular weight heparin) in patients with posterior circulation stroke?

Enoxaparin in Posterior Circulation Stroke

Enoxaparin is not recommended for routine treatment of posterior circulation stroke but should be used primarily for venous thromboembolism (VTE) prophylaxis in immobilized patients, starting 24-48 hours after stroke onset. 1

Role in Acute Ischemic Stroke Treatment

• Current guidelines do not support the use of enoxaparin or other low molecular weight heparins (LMWHs) as primary treatment for posterior circulation stroke, as early anticoagulation has not demonstrated improved outcomes in terms of mortality or stroke recurrence 1
• Early administration of enoxaparin in acute ischemic stroke, including posterior circulation stroke, is associated with increased risk of bleeding complications without clear evidence of benefit 1
• The only subgroup that showed potential benefit from anticoagulation was patients with large-artery atherosclerosis (>50% stenosis), but this was not specific to posterior circulation 1

VTE Prophylaxis in Stroke Patients

• Enoxaparin is recommended primarily for VTE prophylaxis in immobilized stroke patients 1, 2
• The standard prophylactic dose is 40 mg subcutaneously once daily 2, 3
• Enoxaparin has demonstrated superior efficacy compared to unfractionated heparin (UFH) for VTE prevention in the PREVAIL study (10% vs 18% VTE incidence; relative risk 0.57) 2
• Timing: VTE prophylaxis with enoxaparin should be initiated 24-48 hours after stroke onset to balance bleeding risk with VTE prevention 4, 3

Duration of Treatment

• Enoxaparin should be continued until the patient becomes independently mobile 3
• For patients remaining immobile for longer than 30 days, ongoing VTE prophylaxis with enoxaparin is recommended 3
• The typical duration in clinical trials was approximately 10 days (range 6-14 days) 2

Special Considerations

• Anticoagulants including enoxaparin are contraindicated during the first 24 hours after treatment with intravenous rtPA 1
• For patients with renal impairment (CrCl <30 mL/min), dose adjustment or alternative anticoagulation with unfractionated heparin may be necessary 3, 5
• For very high-risk patients or those weighing >150 kg, dosage adjustments may be required 3, 5

Combination Approach

• Early mobilization should be encouraged alongside pharmacological prophylaxis 4, 3
• For patients at very high risk of VTE, a combination of mechanical prophylaxis (intermittent pneumatic compression) and pharmacological prophylaxis with enoxaparin may provide optimal protection 4, 3
• The use of anti-embolism stockings alone is not recommended for post-stroke VTE prophylaxis 4

Safety Considerations

• Monitor for bleeding complications, particularly in patients with severe stroke 1
• In the PREVAIL study, the frequency of symptomatic intracranial hemorrhage was similar between enoxaparin and UFH groups (1% for both) 2
• Major extracranial bleeding was slightly higher with enoxaparin compared to UFH (1% vs 0%) 2

In summary, while enoxaparin has not demonstrated efficacy as a primary treatment for posterior circulation stroke, it plays an important role in VTE prevention for immobilized stroke patients. The decision to use enoxaparin should balance the risk of VTE against potential bleeding complications.