Three randomized trials published in The New England Journal of Medicine have failed to prove that endovascular therapy results in better clinical outcomes than standard medical therapy in patients with acute ischemic stroke.
In the first head-to-head trials to assess clinical outcomes, endovascular treatment offered no extra benefits when given in addition to or instead of intravenous (iv) tissue plasminogen activator (tPA), or when imaging was used to predict treatment response.
The Interventional Management of Stroke (IMS) III trial investigators, led by Joseph Broderick (University of Cincinnati Neuroscience Institute, Ohio, USA), randomly assigned patients previously given iv tPA to receive additional endovascular therapy or not. The proportion of patients with good functional outcomes (modified Rankin Scale [mRS] ≤2) at 90 days was 40.8% among 434patients given endovascular therapy after tPA and 38.7% among 222 given iv tPA only.
The 1.5 percentage-point difference after accounting for stroke severity was not significantly different, despite endovascular therapy resulting in partial or complete reperfusion rates ranging from 65% to 81%, depending on the occlusion site.
In the Local versus Systemic Thrombolysis for Acute Ischemic Stroke (SYNTHESIS Expansion) trial, Alfonso Ciccone (Carlo Poma Hospital, Mantua, Italy) and team provided either endovascular therapy alone or iv tPA alone. 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). Notably, patients in the endovascular group did not start treatment until an hour after the tPA group, with median onset-to-treatment times of 3.75 hours and 2.75 hours, respectively.
Symptomatic intracerebral hemorrhage occurred in about 6% of patients in both trials, but neither found an increased risk with endovascular treatment.
The Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy (MR RESCUE) trial also found no outcome differences among 118 patients assigned to endovascular treatment or to standard tPA therapy, with both groups achieving average mRS scores of 3.9.
In addition, the investigators, led by Chelsea Kidwell (Georgetown University, Washington, DC, USA), stratified patients according to whether or not they had a substantial proportion of potentially salvageable tissue on brain imaging, defined as at least 30% of the at-risk area. But again, the average mRS scores did not differ according to whether patients were given endovascular or standard treatment, at 3.9 and 3.4, respectively, among those with favorable imaging findings and 4.0 and 4.4 among those without.
In an accompanying editorial, Marc Chimowitz (Medical University of South Carolina, Charleston, USA) observes that, although the trial results were generally negative, they do provide some future research directions; He highlights the limitations of the MR RESCUE study, which need addressing with larger trials using more up-to-date embolectomy devices.
Also, subgroup analyses of IMS III suggests that endovascular treatment could add benefit to iv treatment if initiated very early after stroke onset, although Chimowitz notes that "providing such rapid treatment is challenging."
As recruiting patients to new trials will be difficult, "a decision by Medicare to place a moratorium on reimbursement for endovascular treatment of acute ischemic stroke outside of randomized trials would facilitate recruitment in these urgently needed trials," he says. "Once the new trials are completed, endovascular treatment will have been given ample opportunity to prove itself."
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