The authors have undertaken a systematic review and meta-analysis to investigate the efficacy and safety of endovascular treatment (EVT) for acute ischemic stroke due to medium vessel occlusion (MeVO). ^{Reference Mustafa, Panigrahi and Haldar1} The study analyzed two randomized controlled trials (RCTs) (DISTAL and ESCAPE-MeVO) involving 1073 patients and compared EVT with best medical treatment (BMT). EVT did not lead to better 90-day functional outcomes compared to BMT. EVT was associated with a significantly higher risk of symptomatic intracerebral hemorrhage (SICH) and serious adverse events (SAEs) compared to BMT. The analysis included rigorous trial sequential analysis. Limitations include the limited number of RCTs available, the lack of patient-level data and the limited representation of certain specific occlusion subtypes. The authors excluded the DUSK (retrospective analysis) and the DISCOUNT studies, the latter which was terminated prematurely because of futility and safety concerns after partial recruitment. ^{Reference Clarençon, Durand-Zaleski and Premat2}

These studies highlight the unique challenges in treating MeVO and distal vessel occlusions (DVO) with thrombectomy. Recanalization rates were lower, and SAEs were higher due to the technical difficulties. Workflow times were longer, highlighting delays in randomization and consent. Poorer collateral circulation and general anesthesia make time very critical. These patients also received thrombolytics at a higher rate than those in real-world registries. This factor may have further limited the effectiveness of EVT, increased the risk of SICH and provided a relative advantage to the BMT arm. Limited patients with dominant M2 occlusions were included, as prior non-randomized data have demonstrated the safety and benefit of EVT in this subgroup. Many were preferentially treated outside of trial settings, thereby limiting their enrollment in recent RCTs. Also, stent retrievers were used as the first-line treatment. They carry an increased risk of complications for deployment and removal in smaller, more tortuous arteries.

Current evidence does not support the routine use of EVT for MeVO over standard BMT. However, the methodological limitations highlighted should be taken into account, and the results need to be interpreted with caution. Several EVT trials for MeVOs are also ongoing. ^3–5

Specific high-risk populations, such as older patients with less severe deficits and higher baseline disability, may be better treated with BMT. Aggressive endovascular therapies could be offered to young patients with severe deficits and involvement of eloquent distal vessels. Future RCTs and combined patient-level data analysis are expected to clarify the role of EVT in MeVO, particularly as new devices and better patient selection criteria are developed.