Aspirin Restart Guidelines After Subdural Hematoma

Immediate Management and Risk Stratification

• All antiplatelet agents, including aspirin, must be discontinued immediately upon diagnosis of subdural hematoma to prevent hematoma expansion, as recommended by the American Heart Association 2, 3, 4, 1
• The acute period of highest risk for hematoma expansion is the first 1-2 weeks after hemorrhage, according to the American Stroke Association 2, 3, 1
• Obtain baseline brain imaging (CT or MRI) to document the hemorrhage extent, as suggested by the American College of Radiology 1
• Mechanical heart valves are associated with the highest thrombotic risk, and aspirin can be restarted at 7-10 days, as recommended by the American College of Cardiology 2, 1
• Atrial fibrillation with CHADS2 score ≥4 is a high-risk condition for thromboembolism, and aspirin restart should be considered at 7-10 days, according to the American Heart Association 1
• Recent acute coronary syndrome or coronary stent placement (especially within 6 months) is a high-risk condition for thromboembolism, and aspirin restart should be considered at 7-10 days, as recommended by the European Society of Cardiology 5, 6
• History of prior stroke or TIA while off antiplatelet therapy is a high-risk condition for thromboembolism, and aspirin restart should be considered at 7-10 days, according to the American Stroke Association 2
• Lobar location of subdural hematoma suggests possible cerebral amyloid angiopathy with higher rebleeding risk, and aspirin restart should be delayed or avoided, as recommended by the American Academy of Neurology 2, 3, 1
• Multiple microbleeds on MRI indicate underlying microangiopathy, and aspirin restart should be delayed or avoided, according to the American Stroke Association 2, 1
• Elderly patients with lobar hemorrhage are at particularly high risk for amyloid angiopathy, and aspirin restart should be delayed or avoided, as recommended by the American Geriatrics Society 1

Timing Algorithm

• Restart aspirin at 7-10 days after the original hemorrhage for very high thromboembolism risk patients, such as those with mechanical heart valves or high CHADS2 score atrial fibrillation, as recommended by the American College of Cardiology 1
• Obtain repeat brain imaging before restarting to confirm hemorrhage stability, as suggested by the American College of Radiology 1
• Wait at least 1-2 weeks before restarting aspirin for standard risk patients, according to the American Stroke Association 2, 3, 4, 1
• Confirm hemorrhage stability with repeat CT or MRI before restarting, as recommended by the American College of Radiology 1
• Wait 3-4 weeks or longer before considering restart for high hemorrhage risk patients, such as those with lobar hemorrhage or multiple microbleeds, according to the American Academy of Neurology 2, 3

Special Considerations

• Aspirin may be continued if the hemorrhagic transformation is asymptomatic and minimal, depending on the underlying indication, as recommended by the American Stroke Association 3, 4, 1
• This represents a different pathophysiology than primary subdural hematoma, according to the American Stroke Association 3, 4

Critical Pitfalls to Avoid

• Never delay obtaining repeat imaging before restart, as clinical assessment alone is insufficient, as recommended by the American College of Radiology 1
• Do not restart both antiplatelet agents simultaneously if patient was on dual therapy, as the thrombotic risk can be managed with aspirin alone initially, according to the European Society of Cardiology 6
• Do not use higher aspirin doses, as standard low-dose aspirin (81 mg) is appropriate when restarting, as recommended by the International Stroke Society 7