A Myth Debunked: the Results of SYNTHESIS Expansion and IMS III

the results of two key clinical trials assessing the clinical efficacy of endovascular management in acute ischemic stroke were presented at the annual meeting of the International Stroke Conference (ISC) in Honolulu. The trials, SYNTHESIS expansion and IMS-III, had received great attention from many neurologists and neurointerventionalists, as they were multicenter, randomized, controlled trials comparing clinical results of endovascular approach versus standard intravenous (IV) recombinant tissue plasminogen activator (tPA) alone. Although it had already been demonstrated that endovascular treatment had higher recanalization rates than standard medical care (IV tPA), clinical outcomes of the two methods had not yet been compared directly. The SYNTHESIS expansion trial, led by Alfonso Ciccone (Carlo Poma Hospital, Mantua, Italy), randomly assigned 362 acute ischemic stroke patients within 4.5 hours of symptom onset to receive IV tPA or intraarterial endovascular treatment, including intraar-terial thrombolysis with tPA, mechanical clot disruption or retrieval, or a combination of these interventions. This study was initiated under the hypothesis that " the disadvantage of endovascular treatment in terms of time spent may be offset by more effective recanal-ization achieved with endovascular therapy. " This hypothesis was supported by the preliminary results of the SYNTHESIS study. The primary outcome of survival (free from disability , modified Rankin score (mRS) 1) was assessed at 3 months. 30.4% of 181 patients given endovascular therapy and 34.8% of 181 patients given tPA were free of disability (mRS 1). This result demonstrated that intraarterial intervention was not superior to standard medical care for patients with acute ischemic stroke. In addition, there were no between-group differences in mortality at 90 days (14.4% in the endovascular group versus 9.9% in the IV tPA group, p = 0.22) or symptomatic intracranial hemorrhage within 7 days (6% in each group). Notably, patients in the endovascular group did not undergo treatment initiation until one hour after the tPA group, with median onset-to-treatment times of 3.75 hours and 2.75 hours, respectively. In conclusion, the clinical benefit of the endovascular treatment of acute stroke, when compared with IV tPA, could not be proven by the SYNTHESIS expansion trial. However, Ciccone and colleagues presented that generalizability of the results may be limited because demonstrating the presence of an occlusion was not necessary for inclusion in the trial. They said that the selection of patients on basis of the demonstration of vascular occlusion with noninvasive method may provide the endovascular treatment superiority. Another recent trial, …