Endovascular Thrombectomy for the Treatment of Large Ischemic Stroke: A Systematic Review and Meta-Analysis of Randomized Control Trials

Abstract

Background and objectives: Endovascular thrombectomy has previously been reserved for patients with small to medium acute ischemic strokes. Three recent randomized control trials have demonstrated functional benefit and risk profiles for thrombectomy in large-volume ischemic strokes. The primary objective of the meta-analysis was to determine the combined benefit of endovascular thrombectomy in patients with large-volume ischemic strokes and to determine the risk of adverse events after treatment.

Methods: We systematically searched Medical Literature Analysis and Retrieval System Online, Excerpta Medica Database, Scopus, the Cochrane Central Register, and Google Scholar for randomized trials published between January 1, 2010, and February 19, 2023. We included trials specifically comparing endovascular thrombectomy with medical therapy in adults with acute ischemic stroke with large-volume infarctions (defined by Alberta Stroke Program Early Computed Tomography Score 3-5 or a calculated infarct volume of >50 mL). Data were extracted based on prespecified variables on study methods and design, participant characteristics, analysis approach, and efficacy/safety outcomes. Results were combined using a restricted maximum-likelihood estimation random-effects model. Studies were assessed for potential bias and quality of evidence. The primary outcome was an overall ordinal shift across modified Rankin scale scores toward a better outcome at 90 days after either treatment arm.

Results: Three thousand forty-four studies were screened, and 29 underwent full-text review. Three randomized trials (N = 1011) were included in the analysis. The pooled random-effects model for the primary outcome favored endovascular thrombectomy over medical management, with a generalized odds ratio of 1.55 (95% CI 1.25-1.91, I 2 = 42.84%). There was a trend toward increased risk of symptomatic intracranial hemorrhage in the thrombectomy group, with a relative risk of 1.85 (95% CI 0.94-3.63, I 2 = 0.00%).

Conclusion: In patients with large-volume ischemic strokes, endovascular thrombectomy has a clear functional benefit and does not confer increased risk of significant complications compared with medical management alone.

FIGURE 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram for study screening and inclusion/exclusion.

FIGURE 2.

Forest plots for combined results using a restricted maximum-likelihood estimation random-effects model for primary, secondary, and safety outcomes. HC, hemicraniectomy; mRS, modified Ranking scale; REML, restricted maximum likelihood.

FIGURE 3.

Forest plot of combined results in subgroup analysis using a restricted maximum-likelihood estimation random-effects model. ASPECTS, Albert Stroke Program Early Computed Tomography Score; ICA, internal carotid artery; MCA, middle cerebral artery; REML, restricted maximum likelihood.