To date, the benefit of intravenous thrombolysis is confined within 4.5 hours of onset for acute ischemic stroke (AIS) patients without advanced neuroimaging selection. Unpublished pilot EXIT-BT (EXtending the tIme window of Thrombolysis by ButylphThalide up to 6 Hours after onset) suggest the safety, feasibility and potential benefit of intravenous tenecteplase (TNK) in AIS within 4.5 to 6 hours of onset. The current study aims to investigate the efficacy and safety of TNK for AIS within 4.5 to 6 hours of onset.

Inclusion Criteria:

• Age ≥ 18 year
• Acute ischemic stroke confirmed by non-contrast computed tomography and use of CTA for assessment of LVO as determined by local investigators;
• The time from last known well to treatment: 4.5 - 6 hours;
• NIHSS ≥ 4 at randomization;
• First stroke onset or past stroke without obvious neurological deficit (mRS≤1);
• Uncertainty over the benefits and risks of thrombolysis by researcher;
• Signed informed consent.

Exclusion Criteria:

• Pre-stroke disability (mRS≥2);
• Planned intravenous thrombolysis based on WAKE-UP or EXTEND study criterion;
• Any contraindication to intravenous thrombolysis: Obvious head injury or stroke within 3 months; Subarachnoid or intracranial hemorrhage; History of intracranial hemorrhage; Intracranial tumor, arteriovenous malformation or aneurysm; Intracranial or spinal cord surgery within 3 months; Myocardial infarction within 3 months; Major surgery within 1 month; Gastrointestinal or urinary tract hemorrhage within the previous 30 days; Arterial puncture at a noncompressible site within the previous seven days; Active internal hemorrhage; Coagulation abnormalities: platelet count of <100000/mm3; Aortic arch dissection; Heparin therapy within 24 hours; Infective endocarditis; Oral warfarin is being taken and INR>1.6 or APTT abnormal; Systolic pressure ≥185 mmHg or diastolic pressure ≥110 mmHg; Blood glucose < 50 mg/dl (2.7mmol/L); Neurological deficit after epileptic seizures;
• Pregnancy;
• Allergy to test drugs;
• Comorbidity with other serious diseases;
• Participating in other clinical trials within 3 months;
• Patients not suitable for the study considered by researcher.