The purpose of this study is to determine the efficacy and safety of plasma adsorption for patients of acute ischemic stroke who underwent endovascular thrombectomy due to large vessel occlusion of anterior circulation.

Large vessel occlusive (LVO) stroke has a higher mortality and disability rate than other types of acute ischemic stroke (AIS). Endovascular thrombectomy (EVT) is recommended as a standard treatment for AIS-LVO. However, even if the blood vessels are successfully recanalization, nearly one-third of the patients still die and nearly half remain disabled at 3 months. Inflammation plays a crucial role in the pathophysiological cascade of ischemic stroke and related forms of brain injury. Evidence from experimental stroke indicates that targeting cytokines may reduce infarct volume and promote functional recovery. Plasma adsorption (PA) has been applied in the treatment of severe inflammatory diseases, including pancreatitis and sepsis, as well as in the neurological autoimmune diseases, such as myasthenia gravis, multiple sclerosis, and autoimmune encephalitis. We hypothesize that PA can improve functional outcome of AIS-LVO who underwent EVT.

In this study, the experimental group receive EVT and PA, 1 time per day for 3 consecutive days. The control group receive EVT . Two groups will be followed up for 90 days to evaluate the efficacy and safety of PA for patients of AIS-LVO of anterior circulation, who achieve successful recanalization through EVT.

Inclusion Criteria:

1. Age 18-80 years, male or female.
2. Diagnosis of acute ischemic stroke within 12 hours of symptom onset, underwent endovascular thrombectomy (EVT) adhering to current guidelines for large vessel occlusion in the anterior circulation (confirmed by DSA as ICA,MCA-M1,MCA-M2,ACA-A1,ACA-A2 occlusion or tandem lesion) and achieve successful recanalization (mTICI grade 2b/3).
3. Baseline NIHSS after EVT ≥ 6 and ≤25 points.
4. Randomization and the first plasma adsorption can be initiated within 12 hours after EVT.
5. Pre-stroke mRS≤ 2 points.
6. Patient/legally family members have signed the Informed consent form.

Exclusion Criteria:

1. Imaging after EVT indicated malignant brain edema with midline shift or brain herniation and surgical treatment was planned.
2. Parenchymal hemorrhage type 1, or type 2 confirmed by CT.
3. Allergic to any ingredient of the plasma separator, the adsorption device, or the piping.
4. Contraindications to plasma adsorption, platelet count <60×10^9/L,white blood cell<4×10^9/L, uncontrolled hypertension with persistent systolic blood pressure ≥200 mmHg or diastolic blood pressure ≥110 mmHg, uncontrolled hypotension, systolic blood pressure <90 mmHg or diastolic blood pressure <60 mmHg.
5. Previous history of malignant tumors, autoimmune diseases or being treated with immunosuppressants, hormones, or tumor necrosis factor inhibitors.
6. Previous history of organic heart disease and NYHA Class III or IV.
7. Currently taking anticoagulant(dabigatran, rivaroxiban, warfarin, etc.), previous history of serious hematological system disorders, or abnormal coagulation function (international normalized ratio [INR], activated partial thromboplastin time [APTT], prothrombin time [PT] upper limit of the normal range).
8. Severe liver and kidney dysfunction or abnormal laboratory test results（serum aspartate aminotransferase or alanine aminotransferase >3 times the upper limit of normal, serum creatinine>265umol/l(>3mg/dl)）.
9. Pregnancy , lactation or life expectancy of less than 3 months or inability to complete the study for other reasons.
10. Unwilling to be followed up or poor compliance.
11. Current or past participation in other clinical research, or participation in this study within 3 months prior to admission.
12. Other conditions that the researchers think make the patient unsuitable for the study.