When to Avoid Prophylactic Anticoagulation in Acute Stroke
Prophylactic anticoagulation should be avoided in acute stroke patients with evidence of intracranial hemorrhage, recent hemorrhagic transformation, or large ischemic infarcts with high risk of hemorrhagic conversion. 1
General Principles for Anticoagulation in Acute Stroke
- For patients with acute ischemic stroke, early aspirin therapy (160-325 mg) within 48 hours of symptom onset is recommended over therapeutic parenteral anticoagulation 1, 2
- In patients with restricted mobility after ischemic stroke, prophylactic-dose subcutaneous heparin (LMWH or UFH) or intermittent pneumatic compression devices are suggested to prevent venous thromboembolism 1
- LMWH is preferred over UFH for thromboprophylaxis in patients with ischemic stroke and restricted mobility 1
Specific Contraindications to Prophylactic Anticoagulation
Absolute Contraindications:
- Active intracranial hemorrhage or primary hemorrhagic stroke 1, 3
- Severe hemorrhagic transformation of ischemic stroke (HI2, PH1, PH2 in the Heidelberg classification) 3
- Evidence of significant hemorrhage on neuroimaging 1
Relative Contraindications/Situations Requiring Delay:
- Recent thrombolytic therapy (tPA) - anticoagulation should be delayed for at least 24 hours after thrombolysis and only initiated after follow-up imaging confirms absence of hemorrhagic transformation 3, 2
- Large ischemic infarcts with high risk of hemorrhagic conversion 1, 4
- Multiple cerebral microbleeds on MRI 4
- Uncontrolled hypertension 1
- Patients on dual antiplatelet therapy (increased bleeding risk) 5
Timing Considerations
- For primary intracerebral hemorrhage, prophylactic anticoagulation should be delayed until days 2-4 after onset, and only if follow-up imaging shows no expansion of hemorrhage 1, 6
- In patients with minor hemorrhagic transformation (HI1), antiplatelet therapy may be initiated within 24-48 hours after confirming no progression of bleeding 3
- For more severe hemorrhagic transformations, anticoagulation should be delayed for 7-10 days 3
- In patients with large ischemic strokes, anticoagulation should be delayed until the risk of hemorrhagic transformation decreases (typically 5-7 days) 1, 4
Alternative Approaches When Anticoagulation is Contraindicated
- Intermittent pneumatic compression devices should be applied as early as possible, ideally within 24 hours of admission 3, 7
- Early mobilization (between 24-48 hours after stroke onset) should be encouraged when clinically appropriate 3
- Adequate hydration should be maintained 3
- Elastic compression stockings alone are not recommended for VTE prophylaxis 1, 3
Special Considerations
- For patients with high thromboembolic risk (mechanical heart valves, intracardiac thrombi), the decision to initiate anticoagulation must carefully balance bleeding versus thrombotic risks 1, 8
- In patients with non-atrial fibrillation indications for anticoagulation (e.g., venous thromboembolism, arterial thrombus), early anticoagulation may be considered if the ischemic stroke is small and there is no evidence of hemorrhage on imaging 8
- For patients with acute ischemic stroke who are "out of window" for thrombolysis, the same principles apply regarding prophylactic anticoagulation - it should be avoided in those with large infarcts or evidence of hemorrhagic transformation 1