Thrombolysis in Warfarin-Treated Patients
Thrombolysis can be administered to patients on warfarin only if the INR is ≤1.7 at the time of treatment. This is the established threshold that balances the risk of symptomatic intracerebral hemorrhage against the potential benefit of reperfusion therapy 1.
Key Decision Points
When Thrombolysis IS Permitted
Patients on warfarin with INR ≤1.7 may receive intravenous tissue plasminogen activator (tPA) for acute ischemic stroke according to American guidelines 2, 1.
Large registry data from 45,074 patients demonstrates that warfarin treatment with INR ≤1.7 does not increase the risk of symptomatic intracerebral hemorrhage (adjusted OR 1.23,95% CI 0.72-2.11), mortality, or worsen functional outcomes at 3 months compared to non-warfarin patients 1.
The INR must be verified at ≤1.7 before administering thrombolysis—this is a hard cutoff, not a guideline suggestion 2, 1.
When Thrombolysis IS Contraindicated
Thrombolysis is absolutely contraindicated if the patient reports taking warfarin but no reliable information is available about recent INR values or timing of last dose 2.
European guidelines are more restrictive and preclude tPA use in anticoagulated patients altogether, regardless of INR 2, 1.
If INR is >1.7, thrombolysis cannot be given due to unacceptable hemorrhagic risk 2, 1.
Management of Warfarin-Related Hemorrhage After Thrombolysis
If intracerebral hemorrhage occurs following tPA administration in a warfarin patient:
Immediately infuse 6-8 units of platelets plus cryoprecipitate containing factor VIII to rapidly correct the systemic fibrinolytic state created by tPA 3.
Administer intravenous vitamin K to reverse warfarin effect 3.
Consider 4-factor prothrombin complex concentrate (PCC) 25-50 U/kg IV plus vitamin K 5-10 mg by slow IV infusion for life-threatening bleeding, targeting INR <1.5 4.
Critical Caveats
The 30-day mortality rate for ICH after fibrinolysis exceeds 60%, as these hemorrhages tend to be massive and multifocal 3. This underscores why the INR ≤1.7 threshold must be strictly observed.
Patients on warfarin who meet the INR criterion tend to be older, have more comorbidities, and present with more severe strokes compared to non-anticoagulated patients, but when INR ≤1.7, thrombolysis outcomes remain equivalent 1.
Do not delay thrombolysis to reverse a subtherapeutic INR (≤1.7)—these patients can proceed directly to treatment within the appropriate time window 1.
For novel oral anticoagulants (NOACs), the situation differs entirely: it is not known whether patients receiving dabigatran, rivaroxaban, or apixaban can be treated safely with thrombolytic agents for acute ischemic stroke, and current evidence suggests thrombolysis is contraindicated if NOAC intake is reported without clear information on timing 3, 2.