Endovascular Thrombectomy With and Without Intravenous Thrombolysis in Extended Time Window

The primary hypothesis being tested in this trial is that ischemic stroke patients in large vessel occlusion of anterior circulation at 4.5 - 9 hours post onset of stroke will have improved clinical outcomes when given endovascular thrombectomy with intravenous thrombolysis compared with that of given direct endovascular thrombectomy alone.

Inclusion Criteria:Patient/Legally Authorized Representative has signed the Informed Consent formAge ≥ 18Clinical signs consistent with an acute ischemic strokeNeurological deficit with a NIHSS of ≥ 6 (deficits judged to be clearly disabling at presentation)Patient is eligible for intravenous thrombolysisPatient is eligible for endovascular treatmentRandomization no later than 8 hours 45 minutes after stroke symptom onset and initiation of IV t-PA must be started within 9 hours of stroke symptoms onset (for stroke with unknown time of onset, the midpoint of the time last known to be well and symptom recognition time)ICA or MCA-M1 occlusion (carotid occlusions can be cervical or intracranial; with or without tandem MCA lesions) by MRA or CTA (including the reconstructed CTA derived from CTP). And target Mismatch Profile on CT perfusion or MRI (ischemic core volume is < 70 ml, mismatch ratio is >/= 1.8 and mismatch volume is >/= 15 ml)Core-infarct volume of Alberta Stroke Program Early CT Score (ASPECTS) ≥ 6 based on baseline CT or MR imaging (MRI) (a region has to have diffusion abnormality in 20% or more of its volume to be considered MR-ASPECTS positive)Exclusion Criteria:Acute intracranial hemorrhageAny contraindication for IV t-PAPre-treatment with IV t-PAPregnancy or lactating women. A negative pregnancy test before randomization is required for all women with child-bearing potential.Known (serious) sensitivity to radiographic contrast agents, nickel, titanium metals, or their alloysKnown current participation in a clinical trial (investigational drug or medical device)Renal insufficiency as defined by a serum creatinine > 2.0 mg/dl (or 176.8 µmol/l) or glomerular filtration rate (GFR) < 30 mL/min or requirement for hemodialysis or peritoneal dialysisSevere comorbid condition with life expectancy less than 90 days at baselineKnown advanced dementia or significant pre-stroke disability (mRS score of ≥2)Foreseeable difficulties in follow-up due to geographic reasons (e.g. patients living abroad)Comorbid disease or condition that would confound the neurological and functional evaluations or compromise survival or ability to complete follow-up assessmentsSubject currently uses or has a recent history of illicit drug(s) or abuses alcohol (defined as regular or daily consumption of more than four alcoholic drinks per day).Known history of arterial tortuosity, pre-existing stent, other arterial disease and/or known disease at the femoral access site that would prevent the device from reaching the target vessel and/or preclude safe recovery after MTRadiological confirmed evidence of mass effect or intracranial tumor (except small meningioma)Radiological confirmed evidence of cerebral vasculitisCTA or MRA evidence of carotid artery dissectionEvidence of additional distal intracranial vessel occlusion in another territory (i.e. A2 segment of anterior cerebral artery or M3, M4 segment of MCA) on initial NCCT/MRI or CTA/MRA