No Loss of Thrombectomy Benefit in Late Stroke With Transfer

February 18, 2019

For patients with a large-vessel ischemic stroke in the late window who were found to have salvageable brain tissue on imaging, transfer from a primary stroke center to a thrombectomy-capable hospital did not affect the benefit of thrombectomy, latest results from the DEFUSE 3 trial show.

The new subgroup analysis found that for patients who were transferred from primary stroke centers and for those who were taken directly to the thrombectomy-capable center, rates of functional independence were similar, as were thrombectomy outcomes and rates of symptomatic intracranial hemorrhage and mortality.

The DEFUSE 3 trial, published last year, showed that endovascular thrombectomy was beneficial up to 16 hours after last known well time for patients found to have salvageable brain tissue on perfusion imaging.

The current subgroup analysis, which stratified patients on the basis of whether they were taken directly to the study site or were transferred from a primary center, was presented at last week's International Stroke Conference 2019 and was published online in JAMA Neurology on February 7.

"We found the good-outcome rates after thrombectomy to be almost exactly the same whether the patient was transferred or came directly," lead author Amrou Sarraj, MD, associate professor of neurology at McGovern Medical School at UTHealth, Houston, Texas, told Medscape Medical News.

"Our data show that for patients with a large major vessel ischemic stroke in the late window (6–16 hours after onset) who arrive at a nonthrombectomy hospital, it is worth transferring to a thrombectomy-capable hospital, because if they are found to have salvageable brain tissue on imaging, then they are likely to benefit from the thrombectomy procedure," he said.

Sarraj advised that it is better for patients suspected of having a large-vessel stroke to be taken directly to a thrombectomy center, although official guidelines recommend that all stroke patients be taken to the nearest stroke hospital.

"Transferring between hospitals is not the ideal environment for stroke patients," he said. "They cannot be managed as closely as they would be in a hospital. However, if they do arrive at a primary stroke center, our data show that those transferred and found to be suitable for thrombectomy do just as well as the patients taken directly to the comprehensive stroke center, so transfer is to be strongly encouraged."

He pointed out that in the early-window trials, patients who were transferred for thrombectomy did worse than those taken directly to thrombectomy hospitals, but this does not seem to be the case for late-window patients.

"This is probably because the early-window patients are selected on time alone (within 6 hours from stroke onset), and transferring between hospitals obviously adds time. However, late-window patients are selected by imaging — they are known to have salvageable brain tissue — and whether they have come directly or been transferred doesn't matter. If they still have salvageable brain tissue, they benefit from thrombectomy regardless, and a small transfer delay doesn't seem to make much difference," Sarraj explained.

However, in the DEFUSE 3 study, imaging was performed at the thrombectomy hospital, and the trial stipulated that the thrombectomy procedure had to occur within 90 minutes of the imaging. "So these data do not shed light on different models — for example, doing the imaging at the nonthrombectomy hospital and only transferring those with salvageable tissue," he added.

Also, the study did not record data on how many patients were transferred from nonthrombectomy hospitals and were not found suitable to enter the trial, he noted, "so it does not give us information on how many patients would be transferred unnecessarily."

The current data show that of the 182 patients randomly assigned either to undergo thrombectomy or to receive medical management alone in DEFUSE 3, 66% were transfer patients, and 34% presented directly to a study site.

For transfer patients, the median times from last known well time to arrival at the study site was longer (9.43 vs 9 hours), and collateral profiles were more favorable (hypoperfusion intensity ratio, 0.35 vs 0.42).

The primary outcome — 90-day modified Rankin Scale (mRS) score shift — did not differ between the patients who were transported directly to the thrombectomy center and the patients who were transferred (odds ratio [OR], 2.9 for patients taken directly vs 2.6 for transfer patients).

The overall functional independence rate, defined as a 90-day mRS score of 0–2, in the thrombectomy group did not differ (44% for direct vs 45% for transfer), nor did the treatment effect (OR, 2.0 for direct vs 3.1 for transfer).

Thrombectomy reperfusion rates, mortality, and symptomatic intracranial hemorrhage rates also did not differ between direct and transfer patients.

The DEFUSE 3 study was supported by grants from the National Institute of Neurological Disorders and Stroke. Sarraj is the principal investigator of the SELECT and SELECT 2 trials and has an unrestricted grant from Stryker Neurovascular. He is also a consultant for and is on the speakers bureau and advisory board of Stryker Neurovascular.

JAMA Neurology. Published online February 7, 2019. Abstract

International Stroke Conference (ISC) 2019: Abstract 113. Presented February 7, 2019. Abstract

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