To establish a predictive model and scoring system for predicting severe complications after thrombectomy. This scoring system can be used to identify high-risk patients after endovascular thrombectomy, guide the early use of adjunctive interventions, and provide reference for future clinical trials.

Acute ischemic stroke (AIS) accounts for about 80% of all strokes. The focus of AIS treatment is to restore reperfusion of ischemic territory as soon as possible, promote neurological recovery, reduce disability rate and improve long-term survival rate. In recent years, a series of randomized clinical trials have proved that endovascular thrombectomy (EVT) is safe and effective in the treatment of anterior circulation AIS. EVT has been recommend as the first-line treatment for anterior circulation large vessel occlusion (LVO) stroke by guidelines.

Symptomatic intracranial hemorrhage (sICH) and malignant cerebral edema (MCE) are the two most common severe neurological complications, leading to brain tissue hypoxia and neurological dysfunction. Currently, there is a lack of prediction system to identify patients at high risk for severe complications, who can most likely benefit from adjuvant treatment after thrombectomy to improve patient functional independence and survival rate.

Inclusion Criteria:

1. Symptoms and signs compatible with ischemia in the anterior circulation
2. Internal carotid artery occlusion or middle cerebral artery M1 and M2 segment occlusion confirmed by computed tomographic angiography (CTA)/ magnetic resonance angiography (MRA)/ digital subtraction angiography (DSA)
3. Premorbid mRS ≤1;
4. National Institutes of Health Stroke Score (NIHSS) ≥6 at admission;
5. Onset to puncture time ≤24h;
6. Treated with thrombectomy resulting in mTICI score ≥2b at end of the procedure.

Exclusion Criteria:

1. Intracranial hemorrhage, aneurysm, and arteriovenous malformation before endovascular thrombectomy;
2. Perioperative complications, including dissection and arterial perforation;
3. Anticipated life expectancy <3 months;
4. Critical baseline clinical, laboratory and imaging data are missing;
5. Lack of follow-up results within 72 hours and 90 days after thrombectomy;
6. Pregnant or lactating women;
7. Severe systemic diseases (e.g. advanced cancer), potentially interfering with prognosis;
8. Allergy to contrast media and nitinol;
9. Concurrent participation in a study that would interfere with the establishment of predictive models;
10. Unable to complete the assessment due to mental disorders cognitive or emotional disorders before onset.

At least 1500 patients with anterior circulation acute ischemic stroke due to large vessel occlusion and received endovascular thrombectomy.