Benefit of thrombectomy may be universal
The location of the arterial occlusive lesion and the imaging technique used to select patients for the procedure also do not influence the therapy’s benefits, the researchers said. Although the proportional benefit of thrombectomy plus medical management is uniform across subgroups, compared with medical management alone, patients may have different amounts of absolute benefit.
The results of the DEFUSE 3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke) trial, which were published in 2018, indicated that endovascular thrombectomy provided clinical benefits for patients with acute ischemic stroke if administered at 6-16 hours after stroke onset. As part of the trial’s prespecified analyses, Maarten G. Lansberg, MD, PhD, associate professor of neurology and neurological sciences at Stanford (Calif.) University Medical Center in California, and his colleagues sought to determine whether thrombectomy had uniform benefit among various patient subgroups (e.g., elderly people, patients with mild symptoms, and those who present late after onset).
A total of 296 patients were enrolled in the randomized, open-label, blinded-endpoint DEFUSE 3 trial at 38 sites in the United States. Eligible participants had acute ischemic stroke resulting from an occlusion of the internal carotid artery or middle cerebral artery and evidence of salvageable tissue on perfusion CT or MRI. In all, 182 patients met these criteria and were randomized and included in the intention-to-treat analysis. The researchers stopped DEFUSE 3 early because of efficacy.
The study’s primary endpoint was functional outcome at day 90, as measured with the modified Rankin Scale. Dr. Lansberg and his colleagues performed multivariate ordinal logistic regression to calculate the adjusted proportional association between endovascular treatment and clinical outcome among participants of various ages, baseline stroke severities, periods between onset and treatment, locations of the arterial occlusion, and imaging modalities, such as CT or MRI, used to identify salvageable tissue.
The population’s median age was 70 years, and 51% of participants were women. The median National Institutes of Health Stroke Scale score was 16. When the researchers considered the whole sample, they found that younger age, lower baseline NIHSS score, and lower serum glucose level independently predicted better functional outcome. The common odds ratio for improved functional outcome with endovascular therapy, adjusted for these variables, was 3.1. Age, NIHSS score, time to randomization, imaging modality, and location of the arterial occlusion did not interact significantly with treatment effect.
“Our results indicate that advanced age, up to 90 years, should not be considered a contraindication to thrombectomy, provided that the patient is fully independent prior to stroke onset,” said the researchers. “Although age did not modify the treatment effect, it was a strong independent predictor of 90-day disability, which is consistent with prior studies of both tissue plasminogen activator and endovascular therapy.”
The trial’s small sample size may have allowed small differences between groups to pass unnoticed, said the reseachers. Other trials of late-window thrombectomy will be required to validate these results, they concluded.
The National Institute for Neurological Disorders and Stroke supported the study through grants. Several investigators received consulting fees from and hold shares in iSchemaView, which manufactures the software that the investigators used for postprocessing of CT and MRI perfusion studies. Other authors received consulting fees from various pharmaceutical and medical device companies, including Genentech, Medtronic, Pfizer, and Stryker Neurovascular.
SOURCE: Lansberg MG et al. JAMA Neurol. 2019 Jan 28. doi: 10.1001/jamaneurol.2018.4587.
