Rationale: Randomized evidence for endovascular thrombectomy(EVT) safety and efficacy in patients with large core strokes is lacking.

Aims: To demonstrate EVT efficacy and safety in patients with large core on non-contrast CT or perfusion imaging(CT/MR) and determine if there is heterogeneity of treatment effect in large cores based on the imaging modality.

Design: SELECT2 is a prospective, randomized, multi-center, assessor-blinded controlled trial with adaptive enrichment design, enrolling up to 560 patients.

Procedure: Patients who meet the clinical criteria and have anterior circulation large vessel occlusions with large core on either NCCT(ASPECTS 3-5) or perfusion imaging(CTP[rCBF<30%] and/or MRI[ADC <620]≥50cc) will be randomized in a 1:1 ratio to undergo EVT or medical management(MM) only up to 24 hours of last known well.

Study Outcomes: The distribution of 90-day mRS scores is the primary outcome. Functional independence(mRS=0-2) rate is a secondary outcome. Other secondary outcomes include safety(symptomatic ICH, neurological worsening, mortality) and imaging outcomes.

Analysis: A normal approximation of the Wilcoxon-Mann-Whitney test(the generalized likelihood ratio test) to assess the primary outcome. Functional independence rates, safety and imaging outcomes will also be compared.

Discussion: The SELECT2 trial will evaluate EVT safety and efficacy in large cores on either CT or perfusion imaging and may provide randomized evidence to extend EVT eligibility to larger population.

Registration: ClinicalTrials.gov–NCT03876457

理由：缺乏关于血管内血栓切除术 (EVT) 对大核心卒中患者的安全性和有效性的随机证据。

目的：通过非增强 CT 或灌注成像（CT/MR）证明 EVT 在大核心患者中的疗效和安全性，并根据成像方式确定大核心治疗效果是否存在异质性。

设计：SELECT2 是一项前瞻性、随机、多中心、评估者盲的对照试验，采用适应性富集设计，最多可招募 560 名患者。

程序：符合临床标准并在NCCT（ASPECTS 3-5）或灌注成像（CTP[rCBF<30%]和/或MRI[ADC<620]≥ 50cc) 将以 1:1 的比例随机接受 EVT 或医疗管理 (MM)，仅在最后一次已知的 24 小时内进行。

研究结果：90 天 mRS 评分的分布是主要结果。功能独立（mRS=0-2）率是次要结果。其他次要结果包括安全性（症状性 ICH、神经系统恶化、死亡率）和影像学结果。

分析：用于评估主要结果的 Wilcoxon-Mann-Whitney 检验（广义似然比检验）的正态近似值。还将比较功能独立率、安全性和成像结果。

讨论：SELECT2 试验将在 CT 或灌注成像上评估大核心的 EVT 安全性和有效性，并可能提供随机证据以将 EVT 资格扩展到更大的人群。

注册：ClinicalTrials.gov–NCT03876457