This study aims to evaluate the efficacy of Y-6 sublingual tablets in improving microcirculation dysfunction and reducing thrombo-inflammation in patients who had AIS caused by LVO and received reperfusion therapy. Moreover, we expect to evaluate the safety of using Y-6 sublingual tablet in such study population.

This study rationale is based on the following scheme: in patients with acute ischemic stroke caused by LVO, receiving reperfusion therapy may cause futile recanalization and thus lead to microcirculation dysfunction and thrombo-inflammation as consequences. Cilostazol has antiplatelet effects and BBB protection and Dexborneol has anti-inflammatory effects; therefore, the multi-component tablet may exert neuroprotective effects in terms of improving microcirculation dysfunction and reducing thrombo-inflammation in patients with AIS after reperfusion therapy.

The primary purpose of this study is to investigate the proportion of modified-Rankin scale (mRS) score recovered to 0~1 score at 90±7 days after randomization.

The follow-up duration is 3 months, and the visit schedule is as follows: Subjects enrolled based on randomization procedures will receive visits at screening/baseline period, 24 ± 2 hours, 7 ± 2 days, 28 + 3 days and 90 ± 7 days after randomization, and in case of any events.

Inclusion Criteria:

• 35 years old ≤ Age ≤ 80 years old;
• Patients with acute ischemic stroke diagnosed within 24 hours of onset (time from onset to start of endovascular treatment);
• Patients with first stroke or mRS score 0-1 prior to this onset ;
• Patients with acute intracranial large vessel occlusion (LVO) confirmed by imaging examination, including occlusion of intracranial segments of internal carotid arteries, T-shaped bifurcation, MCA M1 and/or M2 segments and ACA A1 and/or A2 segments;
• ASPECTS score ≥ 6 when screening;
• 6<NIHSS score ≤ 25 after this onset;
• Patients who had the indications for mechanical thrombectomy and were scheduled for endovascular treatment;
• Patients or his/her legal representatives were able to understand and sign the informed consent.

Exclusion Criteria:

• Severe disorder of consciousness: NIHSS 1a consciousness level ≥2 points;
• Patients with definite history of intracranial hemorrhage, including parenchymal hemorrhage, intraventricular hemorrhage, subarachnoid hemorrhage, subdural/external hematoma, etc. when screening;
• Patients with previously diagnosed intracranial tumor, arteriovenous malformation, or aneurysm when screening;
• Patients with bilateral LVO at anterior circulation or LVO at posterior circulation when screening;
• Patients with LVO of unknown or rare etiology, e.g., due to dissection, vasculitis, etc. when screening;
• Patients who have received treatment with tirofiban, warfarin, novel oral anticoagulants, argatroban, snake venom, defibrase, lumbrokinase or other defibrase therapy after onset, or platelet count <100×10^9/L;
• Patients with severe hepatic insufficiency or renal insufficiency and received dialysis for various reasons when screening (severe hepatic insufficiency was defined as ALT > 3 × ULN or AST >3 × ULN; severe renal insufficiency was defined as serum creatinine >3.0 mg/dl (265.2 μmol/L) or creatinine clearance < 30 ml/min);
• Patients with previously diagnosed hemorrhagic tendency (including but not limited to): with hereditary hemorrhagic disorders, such as hemophilia, when screening;
• Patients with refractory hypertension that is difficult to be controlled by medication (systolic blood pressure > 180 mmHg or diastolic blood pressure > 110 mmHg);
• Patients with history of major head trauma or stroke within 1 month prior to randomization;
• Patients who have received intracranial or spinal surgery within 3 months prior to randomization;
• Patients with history of major surgery or serious physical trauma within 1 month prior to randomization;
• Patients with previously diagnosed hemorrhagic retinopathy;
• Male subjects (or their mates) or female subjects who had planned to have a child during the whole study period and within 3 months after the end of the study period or were unwilling to use one or more non-drug contraceptive methods (e.g., complete abstinence, condoms, ligation, etc.) during the study period;
• Patients with contraindications to known contrast agents or other contrast agents; patients who are allergic to Cilostazol or Dexborneol;
• Patients who plan to receive other surgical or intervention therapy within 3 months, which might require discontinuation of the study drugs;
• Patients with life expectancy of less than 3 months due to advanced stage of comorbidity;
• Patients who have received treatment of investigational drugs or devices within previous 3 months;
• Other investigator-evaluated conditions which may influence the compliance of patients or where it is not suitable for patients to participate in this trial.