For patients with acute ischemic stroke caused by large vessel occlusion, endovascular thrombectomy has been demonstrated to be the most effective therapy, as approximately 90% of the occluded vessels can be recanalized. However, less than 50% of patients could achieve functional independence, and over 15% died 90 days after stroke. Although the mismatch of successful recanalization with poor prognosis can be attributed to many factors, the infarct core formed during thrombectomy and reperfusion injury after thrombectomy may be among the most important and effective neuroprotective strategies urgently needed.

Remote ischemic conditioning (RIC) is a noninvasive strategy in which one or more cycles of brief and transient limb ischemia confer protection against prolonged and severe ischemia in distant organs. In the transient focal cerebral ischemia-reperfusion model, the application of remote ischemic conditioning before reperfusion or both before and after reperfusion reduces reperfusion injuries and the final infarct size. Because patients with acute ischemic stroke who are treated with endovascular thrombectomy can achieve a high rate of recanalization after focal ischemia, this patient population is akin to the model of transient focal cerebral ischemia-reperfusion. Furthermore, a pilot study has determined the safety and feasibility of remote ischemic conditioning in patients undergoing endovascular thrombectomy. However, whether remote ischemic conditioning could provide clinical benefits to patients with acute ischemic stroke who are treated with endovascular thrombectomy urgently needs investigations.

This study aims to investigate the safety and efficacy of remote ischemic conditioning in improving functional outcomes of patients with acute ischemic stroke treated with endovascular thrombectomy and explore the effect of treatment duration on the treatment outcome of remote ischemic conditioning.

Inclusion Criteria:

1. Age≥18 years；
2. Acute ischemic stroke due to large vessel occlusion in the anterior circulation that is not suitable for intravenous thrombolytic therapy, or has contraindications to intravenous thrombolytic therapy, or treated with intravenous thrombolytic therapy without recanalization;
3. Large vessel occlusion confirmed by computed tomography angiography (CTA) or magnetic resonance angiography (MRA), including the occlusion of the intracranial segment of the internal carotid artery (ICA) and M1 segment of the middle cerebral artery (MCA), is the cause of symptoms, and mechanical thrombectomy is planned within 24 hours from the time last known well;
4. Baseline score of the National Institutes of Health Stroke Scale (NIHSS) ≥ 6 points;
5. Patients or family members signed a written informed consent form.

Exclusion Criteria:

1. Imaging examination revealed the presence of multiple vascular supply areas of cerebral infarction (such as the simultaneous presence of infarction in both anterior and posterior circulation);
2. Absence of femoral artery pulsation, extremely difficult intravascular access, or extremely tortuous large vessels, which are expected to result in the inability to undergo timely endovascular treatment;
3. Difficult-to-control hypertension: continuous monitoring upon admission shows systolic blood pressure ≥180mmHg, or diastolic blood pressure ≥100mmHg;
4. Coma or lethargy patients (consciousness level score ≥2 in NIHSS);
5. Unable to obtain an accurate baseline NIHSS score;
6. Pre-stroke modified Rankin Scale (mRS) score >1;
7. Baseline ASPECTS score ≤5;
8. Presence of bleeding tendency, deficiency of coagulation factors, or oral anticoagulant therapy with INR > 3.0;
9. Baseline blood glucose <2.7mmol/L or >22.2mmol/L;
10. Baseline platelet count < 30*10^9/L;
11. Severe known renal impairment defined as requiring dialysis (hemodialysis or peritoneal dialysis), or if known creatinine clearance rate <30mL/min;
12. Cranial CT or MRI shows intracranial hemorrhage;
13. Cranial CT or MRI shows midline deviation and significant occupying effect;
14. Clinical history, previous imaging examinations, or clinical judgment suggesting intracranial tumors, arteriovenous malformations, or intracranial arterial dissection;
15. History of head injury in the past 3 months;
16. History of life-threatening allergy to contrast agents, nickel, titanium metal, or their alloys;
17. Pregnancy, if women of childbearing age have a positive urinary or serum β-human chorionic gonadotropin (β-hCG) test or are breastfeeding；
18. The life expectancy of patients is less than 6 months, and they cannot be evaluated within 3 months;
19. Limb deformity, soft tissue injury, or other conditions that affect the implementation of distant ischemia adaptation therapy;
20. Participating in other ongoing clinical trials;
21. Other conditions that the investigators believe are not suitable for participation in this study.