How long after a subarachnoid hemorrhage can anticoagulation be restarted?

Timing of Anticoagulation Resumption After Subarachnoid Hemorrhage

There is limited evidence to guide the resumption of anticoagulation after subarachnoid hemorrhage (SAH), but it is generally recommended to wait at least 4 weeks after the event before restarting oral anticoagulation in patients without mechanical heart valves. 1

Assessment Before Restarting Anticoagulation

• A thorough neurological and neurosurgical evaluation is necessary to assess the risk of rebleeding versus the risk of thromboembolism 1
• Angiographic evaluation and treatment of any underlying aneurysm or arteriovenous malformation must be completed before considering anticoagulation resumption 1
• Brain imaging (CT or MRI) should be performed before reinitiating anticoagulation to confirm resolution of the hemorrhage 1

Timing Recommendations

• For patients with SAH and no remediable etiology (such as an aneurysm that has been secured), it may be prudent not to reinitiate oral anticoagulation at all due to the high risk of recurrence 1
• If anticoagulation is absolutely necessary:
  • Wait at least 4 weeks after SAH before restarting oral anticoagulation in patients without mechanical heart valves 1
  • For patients with mechanical heart valves, a shorter period of 1-2 weeks may be considered, though this carries higher risk 1, 2

Special Considerations

• For patients with atrial fibrillation after SAH:

  • Consider left atrial appendage occlusion (LAAO) as an alternative to anticoagulation, ideally within a clinical trial 1, 3
  • If oral anticoagulation is deemed necessary, NOACs may be preferred over vitamin K antagonists due to lower risk of intracranial hemorrhage, though specific comparative studies after SAH are pending 3

• For patients with mechanical heart valves:

  • Temporary interruption of anticoagulation for 1-2 weeks appears relatively safe for patients without previous evidence of systemic embolization 2
  • When restarting is necessary, consider using intravenous heparin initially rather than immediate oral anticoagulation 1

Risk Stratification

• Higher risk of recurrent bleeding is associated with:
  • Lobar location of initial hemorrhage 1
  • Older age 1
  • Presence of microbleeds on gradient echo MRI 1
  • Ongoing anticoagulation 1

Clinical Pitfalls and Caveats

• Avoid "bridging" with heparin when initiating NOACs, as this increases bleeding risk without additional benefit 1
• The decision to restart anticoagulation should weigh individual thromboembolic risk against hemorrhagic risk 3
• In patients with SAH, anticoagulation should not be resumed until any ruptured aneurysm is definitively secured 1
• For patients with very high thrombotic risk but contraindication to long-term anticoagulation after SAH, consider enrollment in clinical trials evaluating alternative approaches 1

The decision to restart anticoagulation after SAH remains challenging due to limited high-quality evidence. Current recommendations are largely based on expert opinion and observational data, highlighting the need for randomized controlled trials in this area.