Reperfusion in the brain: is time important? The DAWN and DEFUSE-3 trials.

(Opening paragraph) Reperfusion therapy using intravenous thrombolysis and mechanical thrombectomy are the only approved treatments for acute ischaemic stroke, but must be administered in a narrow therapeutic window of up to 4.5 and 6 h, respectively. A further meta-analysis by the HERMES (Highly Effective Reperfusion evaluated in Multiple Endovascular Stroke Trials) collaboration has suggested that mechanical thrombectomy may be beneficial up to 7.3 h after stroke onset. However, the results of the DAWN (DWI or CTP Assessment with Clinical Mismatch in the Triage of Wake-Up and Late Presenting Strokes Undergoing Neurointervention with Trevo) and the DEFUSE 3 (Endovascular Therapy Following Imaging Evaluation for Ischaemic Stroke)7 trials may extend this window up to 24 h in carefully selected patients.