Warfarin treatment and thrombolysis in acute stroke

IV thrombolysis is the only approved therapy for acute ischemic stroke. Clinical benefit for approximately 1 in 7 treated patients results when administered within 4.5 hours of stroke onset.1,2 The widespread use of IV thrombolysis is, however, hindered by symptomatic intracranial hemorrhage (sICH), which affects 2%–8% of patients (depending on the definition of sICH employed). While several factors clearly enhance the risk for sICH (such as age, NIH Stroke Scale score, and onset to treatment time), current data on the safety of IV thrombolysis in warfarin-treated stroke patients with subtherapeutic international normalized ratio (INR) are contradictory.3–5 In the United States, warfarin-treated stroke patients are eligible for IV thrombolysis if their pretreatment INR is ≤1.7 and if they present within 3 hours from stroke onset.6 In Europe, current treatment with anticoagulants is an absolute contraindication to IV thrombolysis according to the European Medicines Agency (EMA); this discrepancy has propagated the off-label use of IV thrombolysis in Europe among patients who would otherwise be considered eligible for treatment.