Endovascular Thrombectomy for Acute Ischemic Stroke: A Meta-analysis

Abstract

IMPORTANCE: Endovascular intervention for acute ischemic stroke improves revascularization. But trials examining endovascular therapy yielded variable functional outcomes, and the effect of endovascular intervention among subgroups needs better definition. OBJECTIVE: To examine the association between endovascular mechanical thrombectomy and clinical outcomes among patients with acute ischemic stroke. DATA SOURCES: We systematically searched MEDLINE, EMBASE, CINAHL, Google Scholar, and the Cochrane Library without language restriction through August 2015. STUDY SELECTION: Eligible studies were randomized clinical trials of endovascular therapy with mechanical thrombectomy vs standard medical care, which includes the use of intravenous tissue plasminogen activator (tPA). DATA EXTRACTION AND SYNTHESIS: Independent reviewers evaluated the quality of studies and abstracted the data. We calculated odds ratios (ORs) and 95% CIs for all outcomes using random-effects meta-analyses and performed subgroup and sensitivity analyses to examine whether certain imaging, patient, treatment, or study characteristics were associated with improved functional outcome. The strength of the evidence was examined for all outcomes using the GRADE method. MAIN OUTCOMES AND MEASURES: Ordinal improvement across modified Rankin scale (mRS) scores at 90 days, functional independence (mRS score, 0-2), angiographic revascularization at 24 hours, symptomatic intracranial hemorrhage within 90 days, and all-cause mortality at 90 days. RESULTS: Data were included from 8 trials involving 2423 patients (mean [SD] age, 67.4 [14.4] years; 1131 [46.7%] women), including 1313 who underwent endovascular thrombectomy and 1110 who received standard medical care with tPA. In a meta-analysis of these trials, endovascular therapy was associated with a significant proportional treatment benefit across mRS scores (OR, 1.56; 95% CI, 1.14-2.13; P = .005). Functional independence at 90 days (mRS score, 0-2) occurred among 557 of 1293 patients (44.6%; 95% CI, 36.6%-52.8%) in the endovascular therapy group vs 351 of 1094 patients (31.8%; 95% CI, 24.6%-40.0%) in the standard medical care group (risk difference, 12%; 95% CI, 3.8%-20.3%; OR, 1.71; 95% CI, 1.18-2.49; P = .005). Compared with standard medical care, endovascular thrombectomy was associated with significantly higher rates of angiographic revascularization at 24 hours (75.8% vs 34.1%; OR, 6.49; 95% CI, 4.79-8.79; P < .001) but no significant difference in rates of symptomatic intracranial hemorrhage within 90 days (70 events [5.7%] vs 53 events [5.1%]; OR, 1.12; 95% CI, 0.77-1.63; P = .56) or all-cause mortality at 90 days (218 deaths [15.8%] vs 201 deaths [17.8%]; OR, 0.87; 95% CI, 0.68-1.12; P = .27). CONCLUSIONS AND RELEVANCE: Among patients with acute ischemic stroke, endovascular therapy with mechanical thrombectomy vs standard medical care with tPA was associated with improved functional outcomes and higher rates of angiographic revascularization, but no significant difference in symptomatic intracranial hemorrhage or all-cause mortality at 90 days.