Z: coefficient of confidence, α = 0.05 and Z (1 - α/2) = 1.96. p: The ratio of patients with good neurological recovery results after 90 days p = (p1 + p2) / 2 p1 = 0.36: the rate of patients with good neurological recovery (mRS: 0 - 2) after 90 days when apply mechanical thrombectomy with MERCI, in the Multi-MERCI study was 36%; p2 = 0.59: The proportion of patients with good neurological recovery results after 90 days, in ADAPT study was 59% in the study of Vargas J in 2017.