Thrombolysis After Recent Aspirin Administration
No, thrombolysis is NOT absolutely contraindicated in this scenario, but it significantly increases bleeding risk and requires careful consideration. However, based on the strongest guideline evidence, aspirin given 1.5 hours before planned thrombolysis creates a clinically concerning situation that warrants serious reconsideration of IV thrombolysis in favor of mechanical thrombectomy. 1, 2
Primary Guideline Recommendations
The American Heart Association/American Stroke Association clearly states that aspirin should not be administered within 24 hours before or concurrently with thrombolytic therapy, as this significantly increases the risk of symptomatic intracranial hemorrhage. 1 The Canadian Stroke Best Practice guidelines similarly emphasize that in clinical trials for tPA, antithrombotic drugs (including aspirin) were avoided until after the 24-hour post-thrombolysis scan had excluded intracranial hemorrhage. 3
Critical Clinical Decision Algorithm
If aspirin 300mg was given 1.5 hours before planned thrombolysis:
- Strongly consider withholding IV thrombolysis due to the significantly elevated bleeding risk 1
- Prioritize mechanical thrombectomy as the preferred alternative, as aspirin 300mg given as standard acute stroke treatment is NOT a contraindication for mechanical thrombectomy 1, 2
- This reflects different risk-benefit considerations between IV thrombolysis and endovascular therapy 2
Evidence on Bleeding Risk
The data on aspirin pretreatment and thrombolysis shows conflicting findings:
- Older research (2003) found no increased risk: A prospective study of 300 stroke patients showed ASA pretreatment did not increase symptomatic bleeding after rt-PA (p = 0.15), even with subsequent anticoagulation 4
- More recent registry data (2010) shows increased hemorrhage rates: In 11,865 patients from SITS-ISTR, those on any antiplatelet had higher symptomatic ICH rates (2.5% vs 1.1% in AP-naive patients per SITS-MOST criteria) 5
- Combination therapy carries highest risk: ASA plus clopidogrel showed 13.4% SICH rate per ECASS II criteria and was independently associated with increased SICH risk (OR 2.11,95% CI 1.29-3.45) 5
Important Caveats
The absolute excess of symptomatic ICH with aspirin pretreatment is relatively small (approximately 1.4% increase), which must be weighed against the substantial mortality benefit of thrombolysis (18-50% reduction). 5, 3 However, the American Stroke Association's explicit recommendation to avoid concurrent aspirin administration takes precedence over older observational data. 1
Historical context matters: Earlier AHA guidelines from 2003 reported an unacceptably high incidence of early mortality and intracranial hemorrhage when combining aspirin with thrombolytic agents. 2
Practical Management
If you proceed with thrombolysis despite recent aspirin:
- Document the clinical decision-making and informed consent clearly 5
- Monitor extremely closely for neurological deterioration in the first 24 hours 3
- Obtain brain imaging at 24 hours to exclude intracranial hemorrhage before any additional antiplatelet therapy 3, 1
- Avoid any additional antiplatelet agents until hemorrhage is excluded 3
The safest approach is mechanical thrombectomy when feasible, as aspirin is not a contraindication for this intervention. 1, 2