International Stroke Conference

International Stroke Conference

February 28, 2017
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STRATIS: Real-world experience similar to clinical trial outcomes for stent retrievers

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Mechanical thrombectomy with stent retrievers can be performed safely in a real-world setting with clinical outcomes similar to those seen in randomized clinical trials, according to data from the prospective, observational, single-arm STRATIS registry presented at the International Stroke Conference.

“Our first goal was to determine whether the favorable effects of thrombectomy that were seen in clinical trial populations that were highly selected could be replicated in a real-world cohort with patients who are sicker and with a wider group of practitioners in regular clinical practice,” Jeffrey L. Saver, MD, professor of medicine at the UCLA Comprehensive Stroke Center, told Cardiology Today’s Intervention.

“Our second goal was to attain information about systems of care and pathways of care to identify potential ways that systems could be improved to deliver the therapy better.”

Jeffrey L. Saver, MD
Jeffrey L. Saver

STRATIS enrolled 984 patients (mean age, 67.7 years; 54.2% men; mean NIH Stroke Scale score, 17.3) with acute ischemic stroke due to large vessel occlusion at 55 U.S. sites. All were enrolled within 8 hours of symptom onset, and 63.9% received IV tPA. Of the all patients enrolled, 953 were treated with the Solitaire stent retriever (Medtronic) and 31 were treated with the MindFrame Capture LP stent retriever (MindFrame Inc.) as the first device.

Real-world outcomes

According to the registry data, the median times from stroke onset to arrival at the hospital, door to puncture and puncture to reperfusion were 138.5, 72 and 37 minutes, respectively.

The majority of patients (87.9%) achieved a core lab-adjudicated modified Thrombolysis in Cerebral Infarction (TICI) score of at least 2b, and symptomatic intracranial hemorrhage was experienced by only 1.6%. Additionally, 56.6% of patients achieved a modified Rankin score of 0 to 2, and all-cause mortality was 14.4% at 90 days. The benefit of treatment, however, declined with age, with only 26.5% of patients aged 90 years or older achieving a modified Rankin score of 0 to 2 at 90 days.

Median time from EMS scene arrival to puncture was 152 minutes. Each hour-long delay in time from EMS scene arrival to puncture was linked to an 8.3% relative decline in the likelihood of achieving a modified Rankin score of 0 to 2.

Median door-to-puncture times were significantly shorter for centers enrolling at least 30 patients than those that enrolled fewer patients (67 minutes vs. 86 minutes; P < .001).

“It was a little surprising how quickly sites were getting better at shortening door-to-puncture times, which were faster in this study than they were in the clinical trials,” Saver said. “The median time from door to puncture of 72 minutes was below the 60 minutes recommended by the Society of Neurointerventional Surgery. So we’re not at the ideal, but it’s much better than the substantially longer time that we observed in the randomized trials.”

“This study shows that in real-world practice with sicker patients and in a wider range of hospitals, thrombectomy with the Solitaire stent retriever is performing as well as or better than in the randomized clinical trials, and that’s very good news for this highly effective therapy.”

Direct presentation vs. inter-hospital transfer

In another analysis of the STRATIS data, also presented at the conference, the researchers evaluated the patients according to whether they presented directly to an enrolling hospital or were transferred from another hospital to an enrolling hospital.

At 90 days, outcomes were better in the group of patients who presented directly to the enrolling hospital. Specifically, more patients in the direct group vs. the transfer group achieved a modified Rankin score of 0 to 2 (60% vs. 52.5%; OR = 1.38; 95% CI, 1.06-1.79) or a modified Rankin score of 0 or 1 (47.4% vs. 38%; OR = 1.47; 95% CI, 1.13-1.92). However, mortality was not significantly different between groups (direct, 15.1%; transfer, 13.7%; P = .55).

The researchers also conducted hypothetical calculations to compare direct presentation to an endovascular center vs. inter-hospital transfer. Results suggested that IV tPA could be delayed by up to 22.4 minutes, but thrombectomy would be performed 90.2 minutes sooner.

“An important finding was that patients who go to a nonendovascular hospital first and perhaps receive tPA before being secondarily transferred to the endovascular hospital under a ‘drip-and-ship’ strategy have much longer times from onset to puncture and onset to reperfusion and, as a result, have worse outcomes than patients who go straight to the endovascular hospital. The findings provided further support for the task of changing our stroke regional systems of care,” Saver said.

“The study shows we have to continuously improve our systems to get patients who need thrombectomy to the cath lab as fast as possible while shortening door-to-puncture time at endovascular centers and developing the best ways to route patients in the pre-hospital arena directly to endovascular centers when they would benefit from therapy.”

Future research

The data raise several questions, according to Saver. The observations about patient routing, for instance, suggest that more research studies are necessary to identify the best ways to recognize large vessel occlusion in the ambulance as well as the optimal arrangement for transporting patients.

“One question relates to how much longer patients should travel to go straight to a comprehensive stroke center,” he said. “It might mean delaying IV tPA but undergoing thrombectomy faster. Is a trip that’s 15, 20 or 30 minutes longer where the crossover’s going to be more worthwhile? We need some controlled studies of organization of regional systems of care,” he said.

Saver also noted that more information about long-term processes after the acute period and how they influence outcomes, such as rehabilitation and skilled nursing facilities, would be helpful. – by Melissa Foster

References:

Froehler MT, et al. LB15.

Mueller-Kronast NH, et al. LBP3. Both presented at: International Stroke Conference; Feb. 22-24, 2017; Houston.

Disclosure: Saver reports financial ties with Boehringer Ingelheim, Cognition Medical, Medtronic, Neuravia and Stryker.