Yes, you can thrombolyse a patient taking acetrome (aspirin), but aspirin should be withheld for 24 hours after thrombolysis administration.
Prior aspirin use is NOT a contraindication to thrombolysis in acute ischemic stroke. The key distinction is timing: patients already taking aspirin can receive thrombolysis, but you must delay aspirin administration until 24 hours after thrombolytic therapy 1.
Algorithmic Approach
Pre-thrombolysis Assessment
- If patient is already on aspirin monotherapy: Proceed with thrombolysis without delay 1, 2
- If patient is on dual antiplatelet therapy (aspirin + clopidogrel): Exercise increased caution but thrombolysis is still possible—this combination carries higher symptomatic ICH risk (OR 2.11) but does not significantly worsen mortality or functional outcomes 2
Post-thrombolysis Aspirin Timing
- Standard protocol: Delay aspirin for 24 hours after IV alteplase 1
- Exception: May consider earlier administration if there are concomitant conditions where withholding aspirin poses substantial risk 1
- Emerging evidence: Recent data suggests aspirin at 18-21 hours post-thrombolysis may be safe, showing no increased bleeding events 3, though 24 hours remains the guideline standard
Evidence Quality and Nuances
The 2018 AHA/ASA guidelines (Class I, Level A evidence) explicitly state that aspirin administration is recommended 24-48 hours after stroke onset, with the 24-hour delay specifically for thrombolysis patients 1. This represents the highest quality guideline evidence available.
Critical distinction: The harmful interaction occurs when aspirin is given simultaneously with or immediately after thrombolysis—not when patients are already on aspirin before stroke onset. The MAST-I trial demonstrated that combining streptokinase plus aspirin increased early mortality (OR 2.1) and hemorrhagic complications (OR 2.2) 4. Similarly, the ARTIS trial showed aspirin given early after thrombolysis increased symptomatic ICH risk (OR 3.73) without early antithrombotic benefit 5.
However, the SITS-ISTR registry of 11,865 patients showed that pre-existing aspirin use increased symptomatic ICH only modestly (2.5% vs 1.1% by SITS-MOST criteria), and concluded that "antiplatelet treatment should not be considered a contraindication to thrombolysis" 2.
Common Pitfalls to Avoid
- Do NOT withhold thrombolysis simply because a patient takes daily aspirin—this is guideline-discordant care
- Do NOT give aspirin immediately after thrombolysis to "prevent reocclusion"—this increases hemorrhagic risk without proven benefit 5
- Do NOT substitute aspirin for thrombolysis in eligible patients (Class III: No Benefit) 1
- Exercise heightened vigilance with dual antiplatelet therapy (aspirin + clopidogrel), but this remains a relative rather than absolute contraindication 2
Risk Stratification
The absolute excess symptomatic ICH risk from pre-existing aspirin use is small (1.4% increase) compared to the substantial benefit of thrombolysis demonstrated in randomized trials 2. This favorable risk-benefit ratio supports proceeding with thrombolysis in aspirin users.