The SELECT2 trial showed superior outcomes with endovascular thrombectomy plus medical care compared with medical care only for a large core infarct.
SELECT2 was a prospective, randomized, open-label, phase 3 clinical trial with blinded outcome assessment. A total of 31 sites from the United States, Canada, Europe, Australia, and New Zealand participated. A covariate adaptive randomization allowed for balanced baseline characteristics, and imaging evaluation was standardized.
Participants had a stroke due to occlusion of the internal carotid artery or the first segment of the middle cerebral artery. The median ischemic-core volume was approximately 80 mL and ranged from approximately 60 mL to approximately 120 mL. In total, 352 patients were randomly assigned 1:1 to endovascular thrombectomy (EVT) plus medical care (N=178) or medical care alone (N=174). The median age was 67; 73% were female. The primary outcome was the modified Rankin Scale (mRS) score at 90 days.
Lead author Amrou Sarraj, MD, said that about 81% of patients in the control group had very poor outcomes at 90 days. The thrombectomy group saw a shift towards a more favorable outcome, according to Dr. Sarraj: “This translated to a 60% higher chance of improving the outcome on the mRS by at least one point” (Wilcoxon-Mann-Whitney measure of superiority: 0.60; 95% CI, 0.55-0.65). The generalized odds for achieving a better outcome on the mRS after thrombectomy versus medical care alone was significantly higher: OR, 1.51 (95% CI, 1.20-1.89; P<0.001), with a number needed-to-treat (NNT) of 4.94. A key secondary outcome was functional independence, which was not expected to be high in this population. It was met by 20% of participants in the thrombectomy group and 7% in the medical care group (relative risk [RR], 2.97; 95% CI, 1.60-5.51); the NNT is 7.34. The percentage of participants with independent ambulation in the thrombectomy group was doubled: 38% versus 19% (RR, 2.06; 95% CI, 1.43-2.96; NNT, 5.11).
Symptomatic intracerebral hemorrhage was infrequent and did not increase with thrombectomy (0.6%) versus medical management (1.1%; RR, 0.49; 95% CI, 0.04-5.36). Mortality was similar in the two groups: 38% versus 42% (RR, 0.91; 0.71-1.18). Early neurological worsening was increased, which could be related to infarct edema. In the thrombectomy group, arterial access-site complications occurred in five patients, dissection in 10, cerebral-vessel perforation in seven, and transient vasospasm in 11. Dr Sarraj said these complications did not distract from the overall benefit of thrombectomy in this study population.
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