Aspirin 300mg One Hour Before Thrombolysis is a Contraindication
Aspirin should NOT be administered within 24 hours before or concurrently with thrombolytic therapy for acute ischemic stroke, as this significantly increases the risk of symptomatic intracranial hemorrhage. 1
Critical Timing Requirements
The American Heart Association/American Stroke Association establishes clear guidelines that aspirin must be delayed until 24 hours after IV alteplase administration to minimize bleeding complications. 1 This represents a mandatory contraindication when aspirin has been given within this timeframe.
Evidence-Based Rationale
Historical data from 2003 demonstrated an unacceptably high incidence of early mortality and intracranial hemorrhage when combining aspirin with thrombolytic agents. 1
The American Stroke Association specifically notes that administering aspirin concurrently with or immediately after thrombolysis significantly increases symptomatic intracranial hemorrhage risk and should be avoided for at least 24 hours post-thrombolysis. 1
Even without thrombolysis, aspirin causes a 0.1% absolute increase in intracranial hemorrhage risk in acute stroke patients, as demonstrated in the International Stroke Trial and Chinese Acute Stroke Trial. 1
Clinical Algorithm for This Scenario
If aspirin 300mg was given 1 hour before planned thrombolysis:
- Thrombolysis should be withheld due to the significantly elevated bleeding risk 1
- Consider mechanical thrombectomy as an alternative, as aspirin 300mg given as standard acute stroke treatment (160-300mg within 24-48 hours) is NOT a contraindication for mechanical thrombectomy 1, 2
- The risk-benefit profile differs substantially between IV thrombolysis and mechanical thrombectomy regarding recent aspirin exposure 1
Standard Post-Thrombolysis Protocol (When Done Correctly)
When thrombolysis is administered to aspirin-naive patients:
- Hold all antiplatelet agents until 24 hours post-thrombolysis 1
- Perform brain imaging at 24 hours to exclude intracranial hemorrhage 1, 3
- After confirming no hemorrhage, initiate aspirin 160-325mg for secondary prevention 1, 3
Context for Cardiac Thrombolysis
The situation differs for STEMI management, where aspirin administration at the time of fibrinolysis is mandatory 4. This reflects the different bleeding risk profiles between cardiac and cerebral thrombolysis, where intracranial hemorrhage carries catastrophic consequences.
Important Caveat
Research demonstrates that aspirin combined with thrombolytic therapy provides additive benefits in myocardial infarction without excessive bleeding rates 5, 6, but these findings do not apply to stroke thrombolysis where the consequences of intracranial bleeding are far more severe.