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Endovascular Therapy for Acute Ischemic Stroke | Journal Scan
Study Questions:
What is the benefit of endovascular therapy (EVT) for acute ischemic stroke?
Methods:
This study was a systematic review and meta-analysis. Databases were searched between January 1, 1995 through May 15, 2015, to identify randomized controlled trials that compared EVT plus intravenous (IV) tissue-plasminogen activator (tPA) (if eligible) with IV tPA alone or standard therapy (if not IV tPA eligible). Trials that used urokinase were excluded. The authors systematically abstracted data from the trials, including the number of patients with a good functional outcome at 90 days (defined as a modified Rankin score of 0-2), all-cause mortality, and symptomatic intracerebral hemorrhage (sICH). Data from the studies were combined using random-effects models. A meta-regression analysis was also performed to evaluate the effects of age, sex, stroke severity, IV tPA use, onset to randomization time, and various EVT measures on outcome.
Results:
Eight trials were included in the analysis. When compared with IV tPA, EVT improved the rate of good functional outcome (42.4% vs. 31.7%; odds ratio [OR], 1.73; 95% confidence interval [CI], 1.18-2.53; number needed to treat [NNT], 9.3). There was a nonsignificant trend toward lower mortality in the EVT group when compared with the control group (16.2% vs. 17.3%; OR, 0.89; 95% CI, 0.68-1.15). There was no difference in the rate of sICH between the groups. When the analysis was limited to the five most recent trials that used contemporary EVT techniques, the odds of a good outcome with EVT improved when compared with IV tPA (46.1% vs. 26.2%; OR, 2.42; 95% CI, 1.91-3.08; NNT, 5.0). Meta-regression found that recanalization (p = 0.039) and use of a stent retriever device (p = 0.003) were associated with a good functional outcome. Time to randomization was not associated with a good outcome, although these data were inconsistently reported.
Conclusions:
This meta-analysis of contemporary EVT trials for acute ischemic stroke showed that, when compared with IV tPA, EVT was associated with greater odds of a good functional outcome and a trend toward lower mortality, without an increase in sICH.
Perspective:
While there has been tremendous enthusiasm for EVT for acute ischemic stroke until recently, this enthusiasm outpaced the evidence. Recent trials, using modern thrombectomy devices (e.g., stent retrievers) and imaging to identify patients likely to benefit, showed that EVT improves outcomes when compared with IV tPA alone. This study analyzed these recent trials, along with older trials using first-generation thrombectomy devices that did not show benefit for EVT, and found that EVT improves functional outcome. Somewhat surprisingly, time was not associated with improved outcome in the meta-regression; however, this was captured as time to randomization and not consistently reported. Other work has suggested that time to recanalization is a particularly important metric, but this was not captured in the study. Given the benefits of EVT, this work supports the idea that stroke patients should be cared for in a system of care that allows for rapid triage of stroke patients with large vessel occlusions to centers that can perform these procedures.
Keywords: Cerebral Hemorrhage, Endovascular Procedures, Meta-Analysis, Plasminogen, Random Allocation, Regression Analysis, Stents, Stroke, Treatment Outcome, Thrombectomy, Tissue Plasminogen Activator, Triage, Urokinase-Type Plasminogen Activator, Vascular Diseases
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