Endovascular Therapy Versus Best Medical Treatment for Acute Large Vessel Occlusion Stroke With Low NIHSS

• Endovascular therapy (Procedure): Drug: Best medical management All the patients enrolled received standard guideline-directed medical therapy including: monitor vital signs, management of blood pressure, glucose and lipids, antithrombotic (antiplatelet or anticoagulant therapy determined by treating physician) therapy if appropriate. Procedure: Endovascular therapy In the procedure, the methods including mechanical thrombectomy, aspiration thrombectomy, intra-arterial thrombolysis, angioplasty and stenting can be used according to the local interventionalists' choice. Mechanical thrombectomy or aspiration thrombectomy will be recommended as the primary treatment.
• Best medical management (Drug): All the patients enrolled received standard guideline-directed medical therapy including: monitor vital signs, management of blood pressure, glucose and lipids, antithrombotic (antiplatelet or anticoagulant therapy determined by treating physician) therapy if appropriate.

Primary outcomes

• 90-day excellent clinical outcome [90±7 days after randomization]: modified Rankin scale score: 0-1; , 0 \[no disablility\] to 6 \[death\]

Secondary outcomes

• Rate of symptomatic intracranial hemorrhage (sICH) per Heidelberg standard [within 48 hours after randomization]: Heidelberg standard was defined as new intracranial hemorrhage detected by brain imaging associated with any of the item below: 4 points total NIHSS at the time of diagnosis compared to immediately before worsening. 2 point in one NIHSS category. Leading to intubation/hemicraniectomy/ventricular drainage placement or other major medical/surgical intervention. Absence of alternative explanation for deterioration.
• All-cause mortality rate [90±7 days after randomization]: All-cause mortality rate
• Good clinical outcome [90±7 days after randomization]: modified Rankin Scale score: 0-2; 0 \[no disablility\] to 6 \[death\]
• 90-day ordinal modified Rankin Scale score shift [90±7 days after randomization]: ordinal modified Rankin Scale score shift; 0 \[no disablility\] to 6 \[death\]
• Rates of early neurological deterioration [at 24 hours, 72 hours, and 7 days/discharge]: early neurological deterioration during hospitalization
• EuroQol Group 5- Dimension 5-Level (EQ-5D-5L) questionaire score [90±7 days after randomization]: Score range from -0.39 to 1.00, with higher scores indicating better quality of life

Other outcomes

• incidence of adverse events [within 7 days after randomization]: Any ICH post-randomization; vessel perforation; embolus migration in a new territory; rescue endovascular treatment; acute coronary syndrome, venous thrombosis or embolus events; brain herniation, and pneumonia, respiratory failure, circulatory failure, stress ulcers, renal failure, etc.

Sex: All, ages: 18 Years to any

1. Aged 18 years or older;
2. The time from onset of acute ischemic stroke to randomization is within 24 hours. Onset time is defined as the patient's Last Known Well (LKW);
3. Low NIHSS score (2-5 points), with at least one of the following items:

   1. Altered mental status (lethargy or worse);
   2. Facial palsy (facial weakness score ≥ 1 point);
   3. Motor dysfunction (limb weakness score ≥ 1 point);
   4. Aphasia (language disturbance score ≥ 1 point);
   5. Hemispatial neglect (neglect score ≥ 1 point);
4. Intracranial internal carotid artery, proximal M1 or M2 segment of middle cerebral artery occlusion confirmed by cerebral CTA/MRA/DSA before randomization, which is identified as the culprit vessel for stroke;
5. All patients receive CTP/MR perfusion imaging, with a volume of perfusion delay (Tmax>6 s) ≥ 50 mL;
6. Written informed consent is obtained from the patient or legal surrogate, with agreement for long-term follow-up.