When are antiplatelets (anti-platelet agents) started in the setting of blood blister subarachnoid hemorrhage treated with endovascular flow diversion?

Timing of Antiplatelet Therapy in Blood Blister Subarachnoid Hemorrhage Treated with Flow Diversion

For blood blister subarachnoid hemorrhage treated with endovascular flow diversion, antiplatelet therapy should be initiated immediately prior to or during the procedure, with a single antiplatelet agent being the preferred approach to balance thromboembolic and rebleeding risks.

Antiplatelet Regimen Options

Single Antiplatelet Therapy (SAPT) Approach

• Periprocedural administration of weight-adapted eptifibatide IV with heparin during the procedure 1
• Transition to oral prasugrel or ticagrelor as monotherapy 6-24 hours after the procedure 1, 2
• Continue single antiplatelet therapy for approximately one year 2

Dual Antiplatelet Therapy (DAPT) Considerations

• Traditional flow diversion typically requires DAPT, which increases hemorrhagic risk in SAH patients
• DAPT is generally initiated after discussion with family and prior to device placement (average 3.1 days after presentation) 3
• Some centers have successfully used single antiplatelet regimens with newer phosphoryl-bonded flow-diverter stents, showing promising results 1

Timing Considerations

Early Treatment Approach

• Treatment within 48 hours of SAH onset shows favorable outcomes 2
• Some centers report successful treatment within 24 hours of symptom onset 1
• Early treatment (within 2 days) using single antiplatelet therapy has demonstrated safety and efficacy with complete aneurysm occlusion in follow-up studies 2

Factors Affecting Timing Decision

• Patient's clinical grade (better outcomes in good-grade patients) 3
• Presence of hydrocephalus requiring external ventricular drain (EVD) placement (higher risk for bleeding complications) 3
• Type of flow diverter device (newer anti-thrombogenic devices may allow for single antiplatelet therapy) 1

Special Considerations

Hydrocephalus Management

• Patients requiring EVD placement for hydrocephalus may have higher risk for bleeding complications and poor outcomes when antiplatelet therapy is initiated 3
• Consider timing of EVD placement relative to antiplatelet initiation

Rebleeding Risk

• Studies show minimal rebleeding risk with single device flow diversion strategy 3
• One fatal rerupture was reported in a series of 9 patients using single antiplatelet therapy 1

Device Selection

• Newer phosphoryl-bonded flow-diverter stents may allow for safer use of single antiplatelet therapy 1
• Most patients can be successfully treated with a single flow-diverter device 3

Practical Protocol

1. For ruptured blood blister aneurysms requiring flow diversion:

   • Treat within 48 hours of SAH onset when possible
   • Use weight-adapted eptifibatide IV and heparin during the procedure
   • Transition to oral prasugrel or ticagrelor as monotherapy 6-24 hours post-procedure
   • Continue single antiplatelet therapy for one year

2. For patients requiring EVD placement:

   • Consider higher bleeding risk when initiating antiplatelet therapy
   • If possible, place EVD before initiating antiplatelet therapy

3. Device selection:

   • Consider newer anti-thrombogenic flow diverters that may be compatible with single antiplatelet therapy
   • Single device strategy is usually sufficient

This approach has demonstrated favorable outcomes with complete aneurysm occlusion rates of 83-100% in follow-up studies and good clinical outcomes in the majority of patients 1, 2.