In a meta-analysis of randomized clinical trials for the treatment of acute ischemic stroke, an endovascular intervention (such as use of a very small catheter to remove a blood clot) compared to standard medical care (administration of a clot dissolving agent) was associated with improved functional outcomes and higher rates of functional independence at 90 days, but no significant difference in symptomatic intracranial hemorrhage (bleeding in the brain) or all-cause mortality, according to a study in the November 3 issue of JAMA.
The current standard therapy for acute ischemic stroke is intravenous administration of tissue plasminogen activator (tPA). Although intravenous tPA improves survival and functional outcomes when administered as early as possible after onset of ischemic stroke, its use is limited by the narrow therapeutic time window (<4.5 hours), and by several contraindications. As few as 10 percent of patients presenting with ischemic stroke can be eligible for treatment with intravenous tPA. The limitations of its use have led to interest in endovascular therapy for acute ischemic stroke. Endovascular intervention improves blood flow but clinical studies examining this therapy have yielded variable results, warranting further examination, according to background information in the article.
Saleh A. Almenawer, M.D., of McMaster University, Hamilton, Ontario, Canada, and colleagues conducted a meta-analysis that included data from 8 trials involving 2,423 patients with acute ischemic stroke (average age, 67 years; 47 percent women), including 1,313 who underwent endovascular thrombectomy and 1,110 who received standard medical care with tPA. For this analysis, endovascular therapy was defined as the intra-arterial use of a microcatheter or other device for mechanical thrombectomy (clot removal), with or without the use of a chemical thrombolytic (clot busting) agent.
The researchers found that endovascular therapy was associated with a significant treatment benefit across measures of functional outcomes. Functional independence at 90 days occurred among 45 percent of the patients in the endovascular therapy group vs 32 percent of the patients in the standard medical care group. Compared with standard medical care, endovascular thrombectomy was associated with significantly higher rates of angiographic revascularization at 24 hours but no significant difference in rates of symptomatic intracranial hemorrhage (5.7 percent vs 5.1 percent) or all-cause mortality at 90 days (218 deaths [16 percent] vs 201 deaths [18 percent]).
"This meta-analysis synthesizes evidence from multicenter randomized clinical trials, and may help inform the design and execution of future studies examining the efficacy of endovascular therapy for acute ischemic stroke. Additional trials are needed to systematically study the relationship of patient-, disease-, and treatment-related variables with outcomes following mechanical thrombectomy, and to identify the ideal patient to undergo endovascular therapy."
Editorial: Thrombectomy for Acute Ischemic Stroke
"Thrombectomy appears to improve functional outcome for selected patients with internal carotid artery or middle cerebral artery main stem thrombus who have limited comorbidities and who are younger than 80 years. For these patients, intravenous recombinant tissue plasminogen activator should be initiated quickly (if the patient has no contraindications) while rapidly preparing for thrombectomy. Perfusion imaging is not essential," write Joanna M. Wardlaw, M.D., F.R.C.R., and Martin S. Dennis, M.D., F.R.C.P., of the University of Edinburgh, United Kingdom, in an accompanying editorial.
"However, clinicians should realize that thrombectomy is not necessarily safer than standard medical care, with similar risks of symptomatic intracranial hemorrhage and all-cause mortality reported by Badhiwala et al, along with potential procedural risks."
"Additional rigorous trials would help to define which additional patients might benefit from thrombectomy and, by how much, including consideration of the effects of comorbidities, advanced age, limits of extractable thrombus location or extent and the latest time window (probably >6 hours). Studies also are needed to determine how to implement thrombectomy in routine practice, including testing the thorny question of who should perform the procedure, and whether the balance of benefit, cost, and service efficiency favor treating just those patients who individually will gain most or treating all patients with a reasonable chance of some worthwhile benefit."
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