in a major international trial, which is expected to lead to a change in clinical practice and the way in which systems of stroke care are organized.
The results of the SELECT2 trial, which was conducted in sites in the United States, Canada, Europe, Australia, and New Zealand, showed that endovascular thrombectomy plus medical care resulted in better clinical outcomes than medical care alone in patients with a large ischemic core who presented within 24 hours after the time they were last known to be well.
The results of the SELECT2 trial were presented at the International Stroke Conference by Amrou Sarraj, MD. Dr. Sarraj is professor of neurology at University Hospitals Cleveland Medical Center–Case Western Reserve University in Ohio. The study was also simultaneously published online in the New England Journal of Medicine.
A similar trial conducted in China, the ANGEL-ASPECT trial, was also presented at the same ISC session and showed very similar results.
These two trials add to another Japanese study reported last year, the RESCUE-JAPAN LIMIT trial, also showing benefit of thrombectomy in patients with large core strokes.
Dr. Sarraj concluded that the results of these three trials together “unequivocally demonstrate the benefit of endovascular thrombectomy in patients with large ischemic core.”
A clear benefit
Approximately 20% of large-vessel occlusion strokes have a large core, but these patients have not been considered candidates for endovascular thrombectomy because of concerns about potential reperfusion injury in necrotic brain tissue, resulting in an increased risk of hemorrhage, edema, disability, and death.
This has resulted in uncertainty about how to manage these patients with a core infarct, Dr. Sarraj noted at the conference presented by the American Stroke Association, a division of the American Heart Association.
The SELECT2 trial involved patients with stroke as a result of occlusion of the internal carotid artery or the first segment of the middle cerebral artery. Patients had a large ischemic core volume, defined as an ASPECTS (Alberta Stroke Program Early Computed Tomography Score) of 3-5, or a core volume of at least 50 mL on imaging. They were randomly assigned to endovascular thrombectomy plus medical care or to medical care alone.
The trial was aiming to enroll 560 patients but was stopped early for efficacy after 178 patients had been assigned to the thrombectomy group and 174 to the medical-care group.
The primary outcome – the generalized odds ratio for a shift in the distribution of modified Rankin scale scores toward better outcomes in favor of thrombectomy was 1.51 (P < .001).
“This translates into a 60% probability of achieving a better functional outcome in patients receiving thrombectomy, with a number needed to treat of five. That means five patients need to be treated with thrombectomy for one to achieve a better functional outcome,” Dr. Sarraj stated.
The secondary outcome of functional independence at 90 days (a score on the modified Rankin scale of 0-2) occurred in 20% of the patients in the thrombectomy group and 7% in the medical-care group (relative risk, 2.97), with a number needed to treat of seven.
Independent ambulation (a score on the modified Rankin Scale of 0-3) at 90 days occurred in 37.9% of the patients in the thrombectomy group and in 18.7% of the patients in the medical-care group (relative risk, 2.06), with a number needed to treat of five.
Mortality was similar in the two groups.
The results for other secondary outcomes were generally in the same direction as those of the primary analysis, with the possible exception of early neurologic improvement, the authors reported.
The incidence of symptomatic intracranial hemorrhage was low in both trial groups, occurring in one patient in the thrombectomy group and two in the medical care group.
The investigators pointed out that previous studies have reported rates of symptomatic intracranial hemorrhage in patients with large ischemic core lesions that are higher than those in this trial. “Therefore, the low percentage of patients with symptomatic intracranial hemorrhage observed in both trial groups was unexpected.”
Approximately 20% of the patients in the thrombectomy group had complications associated with the procedure. In the thrombectomy group, arterial access-site complications occurred in 5 patients, dissection in 10, cerebral vessel perforation in 7, and transient vasospasm in 11.
Early neurologic worsening, defined as an increase of 4 or more points on the National Institutes of Health Stroke Scale (NIHSS), occurred in 24.7% in the thrombectomy group and in 15.5% in the medical-care group (relative risk, 1.59).
In a post-hoc analysis, “from which no conclusions can be drawn,” the authors reported, early neurologic worsening was associated with worse functional outcomes at 90 days, and patients who had neurologic worsening had larger ischemic core lesions at baseline (median volume, 107 mL) versus 77 mL among patients without neurologic worsening.
They noted that a potential cause of deterioration in some of these patients was brain edema associated with reperfusion. However, they emphasize that overall, endovascular thrombectomy was associated with better outcomes than medical care alone.
“Two-thirds of patients had core infarct sizes more than 70 mL, and one-third of patients had core infarct sizes of more than 100 mL, but even in patients with large and very large core volumes, thrombectomy was superior to medical care alone,” Dr. Sarraj said.