Endovascular Thrombectomy for Acute Ischemic Stroke Due to Distal Medium Vessel Occlusion: A Systematic Review and Meta-Analysis.

Background

While endovascular thrombectomy (EVT) is the standard treatment for large vessel occlusion, its role in distal medium vessel occlusion (DMVO) remains uncertain. This systematic review and meta-analysis aim to evaluate the efficacy and safety of EVT in patients with acute ischemic stroke (AIS) due to DMVO.

Methods

We systematically searched PubMed, Medline, Embase, Web of Science, and Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov from inception up to February, 2025 reporting the efficacy and safety of EVT for DMVO, compared with best medical management (BMM). Study risk of bias was assessed using the Newcastle Ottawa Scale (NOS) for observational studies and the Cochrane Risk of Bias tool 2 (RoB 2) for randomized controlled studies. Random-effects meta-analyses were performed to pool data. Outcomes of interest included the proportion of excellent functional outcomes (mRS 0-1 at 90 days), the proportion of favorable functional outcome (mRS 0-2 at 90 days), 90-day mortality, and symptomatic intracranial hemorrhage (sICH). We used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach to evaluate the certainty of the evidence. The study protocol was registered on PROSPERO (CRD420250656493).

Results

A total of thirty-seven studies with 12742 patients were included in our meta-analysis. Overall, no significant differences were observed between the EVT and BMM group regarding excellent functional outcome (OR: 1.02, 95% CI: 0.86-1.21) and favorable functional outcome (OR: 1.02, 95% CI: 0.87-1.19). However, the EVT group demonstrated significantly higher odds of mortality (OR: 1.28, 95% CI: 1.07-1.54) and sICH (OR: 1.44, 95% CI: 1.04-1.98) compared with the BMM group. Subgroup analyses indicated EVT was associated with a higher proportion of favorable functional outcome (OR: 1.52, 95% CI: 1.07-2.16) in patients with M2 occlusion (GRADE = Very low). In addition, EVT was associated with lower proportion of favorable functional outcome (OR: 0.61, 95% CI: 0.37-0.98) in patients with ACA occlusion (GRADE = Low). EVT achieved higher proportion of excellent functional outcome (OR: 1.20, 95% CI: 1.02-1.40) (GRADE = Low), but higher risk of mortality (OR: 1.65, 95% CI: 1.17-2.31) and sICH (OR: 2.53, 95% CI: 1.48-4.33) in patients with PCA occlusion (GRADE = Low, GRADE = Moderate, respectively).

Conclusions

Our meta-analysis revealed that, for the broad population of DMVO-AIS, EVT is not associated with improved 90-day functional outcomes and may increase mortality and sICH risks. However, subgroup analyses suggest that effects are not uniform and may be favorable for selected patients, particularly those with M2 occlusions. Notably, these aggregate findings are limited by observational studies with inherent selection bias, so the generalizability may be affected.