Minutes Count in Post-Stroke Endovascular Reperfusion

Pauline Anderson

August 26, 2015

Time is of the essence when it comes to endovascular reperfusion in stroke patients, a new study confirms.

Study patients with an occluded artery who were treated with the Solitaire stent-retrieval device (Covidien) within 120 minutes of symptom onset had a more than 80% chance of a nondisabled outcome, defined as a modified Rankin scale (mRS) score of 0 to 2 at 3 months.

Even a delay of mere minutes can change someone's life, Sunil A. Sheth, MD, clinical instructor, Division of Interventional Neuroradiology, University of California, Los Angeles, told Medscape Medical News.

"There was a very critical dependence on time," said Dr Sheth. "We found that for a 5-minute delay in achieving reperfusion, in opening the blood vessel, 1 out of every 100 patients had a worse outcome."

Dr Sunil A. Sheth

That worse outcome could mean the difference between walking independently and needing a walker, he said.

The research was published online August 17 in Annals of Neurology.

SWIFT, STAR

The study included 202 patients with ischemic stroke from two large stent retriever–based studies (the SWIFT and STAR trials) who had reperfusion therapy for a confirmed anterior circulation occlusion. They were ineligible for or had not responded to intravenous tissue plasminogen activator (t-PA).

The mean patient age was 68 years and 62% of patients were female. Their median National Institutes of Health Stroke Scale (NIHSS) score was 17; the median prestroke mRS score was 0 in 71% and 1 in 16%.

The researchers defined reperfusion as Thrombolysis in Cerebral Infarction scale scores of 2b or 3. They defined time to reperfusion as the time from when the patient was last known to be well until successful reperfusion in all treated vessels.

The study separated patients according to onset-to-reperfusion (OTR) times: 124 to 240 minutes (2 to 4 hours), 241 to 360 minutes (4 to 6 hours), and 361 to 660 minutes (6 to 11 hours). Patients in the longest time window had slightly increased stroke severity and more had diabetes compared with those in the earlier time windows (33% vs 11%; P = .007).

Those in the earlier time window were more likely to have been treated with intravenous tPA (52% vs 43% for the longest time window; P = .078). Importantly, said the authors, time from hospital arrival to groin puncture did not differ between groups.

Multivariate linear regression analysis found that each 5-point increase in NIHSS score was associated with a 16-minute increase in OTR. Female sex and history of hyperlipidemia were associated with reduced OTR of 26 and 29 minutes, respectively. A history of diabetes was associated with a significant delay in OTR of 49 minutes.

The researchers found that functional outcomes at 90 days were best for patients with OTR within 2 to 4 hours (mean mRS score, 1.4), intermediate with treatment in the 4- to 6-hour window (mean mRS score, 2.4), and worst with treatment in the 6- to 11-hour window (mean mRS score, 3.3). Findings were similar in the subset of patients who did not have diabetes and those receiving a single Solitaire pass.

More than two thirds (69%) of patients in the fastest reperfusion group had an mRS score of 0 to 1 while 81% had an mRS score of 0 to 2, and 89% had an mRS score of 0 to 3. In the slowest group, only 23% had an mRS score of 0 to 1, 35% an mRS score of 0 to 2, and 50% an mRS score of 0 to 3.

Rates of symptomatic intracranial hemorrhage were low; there were no between-group differences in these rates or in the length of hospitalization. Nominal increases in mortality with later treatment did not reach statistical significance.

For all seven values of the mRS, the number needed to treat was 30 for 1 more patient to benefit from 15 minutes' faster time to reperfusion. For every 1000 patients treated 15 minutes faster, 34 would have a less disabled outcome. Conversely, for every 5-minute delay in endovascular reperfusion, 1 of every 100 treated patients has a worse disability outcome.

The stent-retrieval devices now being used "are much more effective than anything we've had in the past to open the vessels," said Dr Sheth. He added that these devices have become "the modern-day standard of care," said Dr Sheth.

However, researchers are working to develop even better clot retrieval devices. "In the next 5 or 10 years, we will see improvements in the technology and development of adjunctive devices," said Dr Sheth. For example, physicians are testing a large catheter that suctions out the clot that they use alongside the stent retriever.

Another experimental device resembles a sock-like mesh sleeve that covers and removes the clot and stent retriever, said Dr Sheth.

The results of this study, together with those of other recent trials showing the benefits of stent-retrieval devices, should spur discussion of how best to structure the health delivery system to offer timely endovascular reperfusion, Dr Sheth concluded.

"Time Is Our Enemy"

Invited to comment, Joshua N. Goldstein, MD, PhD, associate professor, Harvard Medical School, and director, Center for Neurologic Emergencies, Department of Emergency Medicine, Massachusetts General Hospital, Boston, said the study was well done.

"The authors showed very nicely that if you do the exact same thing to the exact same patients but you do it faster, you get a dramatic effect on their neurologic outcome."

Looking at the effectiveness of stent-retrieval devices by categorizing patients in terms of time to reperfusion is a much better way to assess neurologic outcomes than simply asking whether these outcomes are good or bad, said Dr Goldstein.

"If you not only look at good versus bad but you ask how good or how bad, you're able to pick up a lot more benefits that you missed by oversimplifying the outcome."

Several trials have determined that patients getting the stent retrieval device are better off than those who don't get it, and this new study is saying that of those who do get the device, patients who get it faster rather than slower do better, said Dr Goldstein. "Time is our enemy," he said.

The study was funded in part by Covidien, now known as Medtronic. Two coauthors Jeffrey Saver and Reza Jahan have served as unpaid site investigators in multicenter trials run by Covidien. University of California regents received payments for these trials based on the number of patients enrolled. The University of California has patent rights in retrieval devices for stroke. Coauthors Elad Levy, Jan Gralla, Raul Nogueira, Osama Zaidat, and Vitor Pereira have served as site investigators and/or consultants for Coviden. Dr Sheth and Dr Goldstein have disclosed no relevant financial relationships.

Ann Neurol. Published online August 17, 2015. Abstract

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