Stent Implantation Versus Balloon Dilation for Acute Anterior Circulation Tandem Occlusion (START)

General inclusion criteria Age 18-85 years old; Acute ischemic stroke and the onset time within 24h; Pre-stroke mRS 0-1; NIHSS score of 6-30 before randomization; Completed randomization within 24h after stroke onset； Subjects are able to sign an informed consent in person or by the legal representative Imaging Inclusion Criteria: Satisfy one of the following criteria:①Within 6 hours of onset, imaging confirmed occlusion of the acute anterior circulation internal carotid artery or the M1 / M2 segment of the middle cerebral artery；②Within 6-16 hours of onset, imaging confirmed acute occlusion of anterior circulation internal carotid artery or M1 / M2 segment of middle cerebral artery followed by DAWN or DEFUSE-3 criteria；③In patients with 16 to 24 hours of onset, imaging confirmed intracranial occlusion of the acute anterior circulation internal carotid artery or M1 / M2 segment of the middle cerebral artery followed by DAWN criteria. Extracranial segment stenosis ≥70% or occlusion in tandem lesions. ASPECT score ≥ 6 points. eTICI≥2b_50 after middle cerebral artery thrombectomy and extracranial balloon dilatation in 10min. General Exclusion Criteria: Participating in other clinical trials; 2.It is planned to carry out selective internal carotid artery stent implantation within 3 months; 3.Intracranial hemorrhage, subarachnoid hemorrhage within 3 months; previous brain tumor (with space-occupying effect). 4.Parenchymal organ surgery or biopsy were performed last 1 month; Any active or recent bleeding (gastrointestinal, urinary, etc.); Parenchymal organ surgery and biopsy were performed last 1 month 5.Difficult to control hypertension: systolic blood pressure> 185mmHg and/ or diastolic blood pressure> 110mmHg. 6.Severe active bleeding or known significant bleeding tendency: platelet count <100X109/L; heparin within 48 hours before surgery, and APTT≥35s; oral warfarin, and INR> 1.7; direct thrombin or factor Xa inhibitors, such as apixaban tablets, rivaroxaban tablets and dabigatran (patients with no history of abnormal coagulation or suspected abnormal coagulation function do not need laboratory results of INR or APTT before enrollment）. 7.Severe heart, liver, kidney, and other organ insufficiencies (glomerular filtration rate <30 ml/min or blood creatinine> 220μmol/L(2.5mg/dl)). 8.Patients occurred acute ischemic cerebral infarction within 48 hours after percutaneous coronary or cerebrovascular intervention or major surgery (if more than 48h, patients may be enrolled). 9. The patient has a history of cerebral vasculitis with clear evidence; 10. Patients with pre-onset neurological or psychiatric disorders that affect the assessment of their condition 11.Women who are known to be pregnant or lactating. 12.Known severe allergy to contrast agents (except for mild rash allergy) 13.Expected survival time less than 1 year (such as combined malignancy, severe cardiopulmonary disease, etc.) 14.Patients unable to complete the follow up (e. g., no fixed residence, overseas patients, etc.). Imaging exclusion criterias: Imaging confirmed the posterior circulatory lesions. Midline displacement of the brain or brain herniation, ventricular occupancy New onset bilateral acute stroke or multiple intracranial macrovascular occlusions. Patients with vascular variants that are difficult to treat with endovascular therapy as displayed by CTA/MRA; The ipsilateral middle cerebral artery and anterior cerebral occlusion were combined.