E-154 A prospective pilot study to assess the safety of endovascular therapy for acute large vessel occlusion with low NIHSS

Introduction Endovascular therapy (EVT) for emergent large vessel occlusion (ELVO) is now the standard of care for disabling strokes. However, there is no sufficient prospective data looking at EVT for ELVO with mild ischemic stroke. Retrospective data suggests that many patients may do poorly without intervention. We present the design and our initial data from our single center study. Methods Our ongoing pilot single arm prospective study (Mild acute Ischemic STroke With lArge VEssel occlusion – MISTWAVE), approved by our institutional IRB, investigates the safety of EVT in patients with ELVO and initial NIHSS of ≤5. Inclusion criteria include anterior circulation or basilar artery ELVO ±IV t-PA before intervention. The initial study protocol aimed for presentation within 12 hours of onset, which later was extended to 24 hours. We exclude patients with ASPECTS score ≤6 on pre-intervention imaging, bleeding diathesis, prior intracranial hemorrhage, or current anticoagulant use. Our primary endpoints are symptomatic cerebral hemorrhage within 24 hours, and/or change in NIHSS by ≥4 points compared to enrollment NIHSS, within 72 hours or during hospitalization. Secondary endpoints are angiographic recanalization grade, disability assessment at 30 and 90 days, and final infarct volume on imaging. Results We screened 28, but we were able to enroll only 3 patients who were treated per study protocol. One additional patient received treatment outside study protocol, and was not included in this analysis. Main reasons for exclusion otherwise were: outside treatment window, worsening NIHSS to more than 5, tandem or extracranial carotid occlusion, and inability to sign consent. The initial NIHSS ranged from 3 to 5. They all underwent successful mechanical thrombectomy for M1 MCA occlusion with TICI 2B recanalization grade. None of the patients suffered symptomatic cerebral hemorrhage, or other periprocedural complications. They were all discharged home with mild or no residual deficits. At early follow up (14, 17 and 40 days), all 3 patients had NIHSS 0, and modified Rankin score 1. Conclusion This is one of the first prospective studies assessing the safety of EVT in patients with low NIHSS and ELVO. Our early results are very limited, but encouraging with excellent radiographic and clinical outcomes, and no significant complications. Our goal is to continue enrollment and utilize the results for a larger multi-center trial. Disclosures G. Toth: None. R. Cerejo: None. J. Tsai: None. K. Uchino: None. S. Hussain: None.