Currently, early reperfusion is considered as the most effective therapy for the treatment of acute ischemic stroke (AIS). Over the past 20 years, intravenous tissue plasminogen activator (IV tPA) has been demonstrated to be the only effective therapy for AIS. More recently, several large randomized clinical trials have concluded the superiority of endovascular mechanical thrombectomy for AIS. Furthermore, with the development of materials and techniques, the occluded artery can be recanalized with high percentage (60%-90%), and the rate of recanalization is still being improved. A great number of AIS patients are now eligible for revascularization therapy and there should be a good prognosis of AIS after recanalizing the occluded artery using mechanical thrombectomy. However, things are never as simple as wished to be. The rate of patients with functional independence is less than 50% and over 15% patients died at 3 months post thrombectomy. The discrepancy between the functional outcome and recanalization rates encourage researchers to explore strategies that further improving the functional outcome of AIS patients.

Remote ischemic conditioning has been demonstrated to reduce cerebral infarct size in mouse model of focal cerebral ischemia. And clinical researches demonstrated the protective effects of remote ischemic conditioning in AIS patient treated with IV tPA,. However, whether remote ischemic conditioning is safe and effective in protecting patients with large-vessel ischemic stroke and undergoing endovascular treatment is still unknown.

In the present study, the investigators will assess the safety and feasibility of remote ischemic condition paired with endovascular treatment for AIS. A single arm of AIS patients treated with endovascular therapy will be recruited, and remote ischemic conditioning will be applied prior to reperfusion therapy and in combination with post reperfusion therapy.

Inclusion Criteria:

1. Acute ischemic stroke where patient is ineligible for intravenous thrombolytic treatment or the treatment is contraindicated, or where patient has received intravenous thrombolytic therapy without recanalization;
2. No remarkable pre-stroke functional disability (mRS ≤ 1);
3. Age ≥18 and ≤ 80;
4. Patient treatable within six hours of symptom onset;
5. Informed consent obtained from patient or acceptable patient's surrogate

Exclusion Criteria:

1. Identified hemorrhagic diathesis, coagulation factor deficiency, or oral anticoagulant therapy with INR > 3.0;
2. Baseline platelet count < 30*109/L;
3. Baseline blood glucose of < 2.7mmol/L or >22.2mmol/L;
4. Renal insufficiency with creatinine ≥ 265 umol/L;
5. Severe, sustained hypertension (SBP > 185 mmHg or DBP > 110 mmHg);
6. Woman of childbearing potential who is known to be pregnant or lactating;
7. Subject participating in a study involving other drug or device trial study;
8. Patients with a pre-existing neurological or psychiatric disease that would confound the neurological or functional evaluations;
9. Unlikely to be available for 90-day follow-up;
10. Contraindication for remote ischemic conditioning: severe soft tissue injury, fracture, or peripheral vascular disease in the upper limbs;
11. Hypodensity on CT or restricted diffusion amounting to an ASPECTS score of <7 on noncontrast CT;
12. CT or MRI evidence of hemorrhage;
13. Significant mass effect with midline shift on CT or MRI scans;
14. Subjects with artery occlusions in multiple vascular territories;
15. Evidence of intracranial tumor.