Stent Retrievers Can Provide Benefits More Than 7 Hours After Stroke Onset

The time window in which endovascular thrombectomy confers benefit in acute ischemic stroke is at least up to 7.3 hours after onset, an extension beyond the current guideline recommendation of up to 6 hours, according to a new meta-analysis.

The study also found that within these first 7 hours, earlier treatment is much better than later treatment, according to lead study author Jeffrey L. Saver, MD, director of the UCLA Comprehensive Stroke Center, Geffen School of Medicine at UCLA in Los Angeles, California. “Every 6 minutes delay in reopening a blocked artery, 1% more of patients will end up severely disabled. While not a complete surprise, having the exact value of 6 minutes delay worsening the outcome of 1 of every 100 patients is a galvanizing number for physicians and nurses involved in acute stroke care,” he said.
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Researchers pooled demographic, clinical, and brain imaging data, as well as functional and radiologic outcomes, from randomized phase 3 trials involving stent retrievers or other second-generation devices in a peer-reviewed publication (by July 1, 2016). The identified 5 trials enrolled patients at 89 international sites.

The researchers determined primary outcome to be degree of disability (mRS range, 0-6; lower scores indicating less disability) at 3 months, analyzed with the common odds ratio (cOR) to detect ordinal shift in the distribution of disability over the range of the mRS; secondary outcomes included functional independence at 3 months, mortality by 3 months, and symptomatic hemorrhagic transformation.

Among 1287 patients (endovascular thrombectomy and medical therapy [n=634]; medical therapy alone [n=653]) enrolled in the 5 trials, time from symptom onset to randomization was 196 minutes. Among the endovascular group, symptom onset to arterial puncture was 238 minutes and symptom onset to reperfusion was 286 minutes. At 90 days, the mean mRS score was 2.9 in the endovascular group and 3.6 in the medical therapy group.

The odds of better disability outcomes at 90 days (mRS scale distribution) with the endovascular group declined with longer time from symptom onset to arterial puncture: cOR at 3 hours, 2.79, absolute risk difference (ARD) for lower disability scores, 39.2%; cOR at 6 hours, 1.98, ARD, 30.2%; cOR at 8 hours, 1.57, ARD, 15.7%; retaining statistical significance through 7 hours and 18 minutes.

Among 390 patients who achieved substantial reperfusion with endovascular thrombectomy, each 1-hour delay to reperfusion was associated with a less-favorable degree of disability and less functional independence, but no change in mortality.

“It is important for primary care providers to educate their patients about the key importance of time to treatment to outcome,” Dr Saver said. “The public should know to activate the 911 system as soon as possible when they detect stroke symptoms in themselves or friends, family, and coworkers. The American Heart/Stroke Association recommends educating patients using to remember: FAST (F—face drooping, A—arm drift, or S—speech difficult, T—time to call 911).”

He said further trials are under way to determine if special brain imaging can identify some late-presenting patients, between 7 and 24 hours after onset, who will still benefit from clot-retrieval therapy.

—Mike Bederka

Reference:
Saver JL, Goyal M, van der Lugt A, et al; HERMES Collaborators. Time to treatment with endovascular thrombectomy and outcomes from ischemic stroke: a meta-analysis. JAMA. 2016 Sep 27;316(12):1279-1288. doi:10.1001/jama.2016.13647.