Effect of Clot Burden Score on Safety and Efficacy of Intravenous Alteplase Prior to Mechanical Thrombectomy in Acute Ischemic Stroke: A Subgroup Analysis of a Randomized Phase 3 Trial ======================================================================================================================================================================================== * Zifu Li * Yu Zhou * Xiaoxi Zhang * Lei Zhang * Yongwei Zhang * Pengfei Xing * Yongxin Zhang * Qinghai Huang * Qiang Li * Qiao Zuo * Xiaofei Ye * Jianmin Liu * Pengfei Yang * on behalf of DIRECT-MT Investigators