Background: Contact aspiration thrombectomy (CAT) using a large-bore aspiration catheter is increasingly performed as one of the major endovascular thrombectomy (EVT) methods around the world. Contact aspiration thrombectomy has been shown to be safe and effective for removal of clots in a recent randomized controlled trial which compared contact aspiration thrombectomy and stent retriever thrombectomy as a first line thrombectomy. Aim of the study: To evaluate contact aspiration thrombectomy clinical outcomes at 90 days as compared to best medical management alone in subjects experiencing an acute ischemic stroke due to proximal anterior circulation large vessel occlusion when treatment is initiated within 24 h after last time seen well.