Efficacy and safety of endovascular treatment for acute ischemic stroke due to medium and distal vessel occlusion: a protocol for a systematic review and meta-analysis.

Introduction: Endovascular thrombectomy (EVT) improves outcomes in large-vessel occlusion (LVO) stroke and has recently shown benefit in dominant M2 occlusions. However, its role in medium vessel occlusions (MeVO) and distal vessel occlusions remains uncertain. This systematic review and meta-analysis evaluates the efficacy and safety of EVT plus usual care versus usual care alone in acute ischemic stroke due to MeVO or distal vessel occlusion. Methods: We will search four electronic databases (Ovid MEDLINE, Embase, CINAHL and Cochrane CENTRAL) from inception to May 2025 without language and other restrictions. Eligible studies will be randomized trials comparing EVT plus medical therapy versus medical therapy alone in adults with acute ischemic stroke due to MeVO or distal vessel occlusion. Paired reviewers will independently screen identified hits for eligibility, extract data from eligible studies, and assess risk of bias using the Risk Of Bias instrument for Use in SysTematic reviews-for Randomised Controlled Trials (ROBUST-RCT). Clinically important outcomes will include functional disability, mortality, neurological function and cognition, quality of life, recanalization, and adverse events. Certainty of evidence will be assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE). Random-effects meta-analyses will be conducted, with pre-defined subgroup analyses planned. Ethics and Dissemination: No ethics approval is required. Results will be disseminated via peer-reviewed publication and conference presentations to inform clinicians, guideline developers, and health system decision-makers.