When can aspirin (acetylsalicylic acid) be started after an intracerebral hemorrhage (ICH)?

When to Start Aspirin After Intracerebral Hemorrhage

Aspirin can be restarted in the days after ICH when there is a strong indication for antiplatelet therapy, though the optimal timing remains uncertain; avoidance for at least 4 weeks in patients without mechanical heart valves might decrease ICH recurrence risk, but earlier initiation may be considered when ischemic risk is high. 1

Primary Guideline Recommendations

The 2015 AHA/ASA guidelines provide the most direct guidance on this question:

• If aspirin monotherapy is indicated after ICH, it can probably be restarted in the days after ICH, although the optimal timing is uncertain (Class IIa; Level of Evidence B) 1

• Antiplatelet monotherapy after any ICH might be considered, particularly when there are strong indications for these agents (Class IIb; Level of Evidence B) 1

• For patients without mechanical heart valves, avoidance of oral anticoagulation for at least 4 weeks might decrease the risk of ICH recurrence (Class IIb; Level of Evidence B) 1

The 2023 World Stroke Organization synthesis confirms that aspirin administration is recommended within 24-48 hours after ischemic stroke onset, but for those treated with IV thrombolysis, aspirin is generally delayed until >24 hours 1. However, this applies to ischemic stroke, not ICH.

Key Decision-Making Algorithm

Step 1: Assess the Indication Strength

• Strong indications include: recent acute coronary syndrome, coronary stents (especially drug-eluting stents), high-risk coronary disease, or documented high thrombotic risk 1
• Weaker indications include: primary prevention, stable coronary disease without recent events 1

Step 2: Stratify ICH Recurrence Risk

Consider these risk factors for ICH recurrence when timing aspirin restart 1:

• Lobar location of the initial ICH (higher recurrence risk)
• Older age (higher recurrence risk)
• Presence and number of microbleeds on gradient echo MRI (higher recurrence risk)
• Apolipoprotein E ε2 or ε4 alleles if known (higher recurrence risk)

Step 3: Apply Timing Based on Risk-Benefit Balance

For patients with strong antiplatelet indications:

• Consider restarting aspirin within days to 1-2 weeks after ICH, particularly for non-lobar hemorrhages 1
• Recent high-quality evidence from China showed that starting aspirin on day 3 after surgery for ICH in high-risk patients reduced ischemic events (20% vs 31%) without increasing intracranial bleeding (1% vs 3%) 2

For patients with moderate indications:

• Consider waiting 4 weeks before restarting aspirin 1
• This timing balances the early high risk of rebleeding against later ischemic risk 1

For patients with lobar ICH:

• Exercise greater caution and consider waiting longer than 4 weeks or avoiding aspirin entirely 1
• Lobar location carries the highest recurrence risk 1

Critical Evidence and Nuances

Supporting Evidence for Early Restart

The 2024 E-start trial from China provides the most recent high-quality evidence: in 269 surgical ICH patients at high risk of ischemic events, starting aspirin 100mg on day 3 post-surgery versus day 30 resulted in:

• Fewer ischemic events: 20% vs 31% (OR 0.56, p=0.041) 2
• No increased bleeding: 1% vs 3% intracranial bleeding 2
• Most patients (63%) had supratentorial deep hemorrhages 2

Conflicting Evidence on Aspirin and ICH Risk

• A 2006 study found that regular aspirin use preceding ICH was an independent predictor of death (RR 2.5), likely due to hematoma enlargement 3
• However, a 2017 UK observational study of 199,079 patients found no increased risk of ICH with low-dose aspirin (RR 0.98) and actually decreased SAH risk with ≥1 year use 4
• This apparent contradiction reflects the difference between aspirin's role in causing versus restarting after ICH 3, 4

Common Pitfalls to Avoid

1. Don't assume all ICH patients should avoid aspirin indefinitely: The guidelines explicitly state antiplatelet monotherapy "might be considered, particularly when there are strong indications" 1

2. Don't treat all ICH locations equally: Lobar ICH has much higher recurrence risk than deep ICH; this should heavily influence timing decisions 1

3. Don't rely solely on medication history: Up to 42-52% of ICH patients with reduced platelet activity were not known to take antiplatelet agents 5, suggesting occult aspirin use or other factors affect platelet function

4. Don't confuse anticoagulation timing with antiplatelet timing: The 4-week recommendation specifically mentions oral anticoagulation; aspirin may be restarted earlier 1

5. Don't ignore mechanical heart valves: These patients require anticoagulation and cannot wait 4 weeks; early resumption may be necessary despite bleeding risk 1

Practical Implementation

For non-lobar ICH with strong antiplatelet indication:

• Restart aspirin 81-100mg daily at 3-7 days post-ICH if clinically stable 1, 2
• Ensure repeat imaging shows no hematoma expansion 1

For lobar ICH or moderate indication:

• Wait 4-6 weeks minimum before restarting 1
• Consider MRI with gradient echo to assess microbleeds before restart 1

For any ICH with mechanical heart valve:

• Individualize timing with cardiology consultation, as anticoagulation (not just aspirin) may be needed much earlier 1