Clinical improvement within 24 hours from mechanical thrombectomy as a predictor of long-term functional outcome in a multicenter population-based cohort of patients with ischemic stroke.

Background Single-center studies have suggested that the early clinical course after mechanical thrombectomy (MT) in patients with ischemic stroke is a clinical predictor of long-term outcome. Objective To analyze the prognostic value of clinical improvement within 24 hours in a population-based multicenter cohort. Methods From a total of 3792 patients with acute ischemic stroke in Catalonia (CICAT registry), 1951 patients were treated with MT. The National Institutes of Health Stroke Scale (NIHSS) score within 24 hours, and follow-up was available in 1666 patients. Percentage variation in the NIHSS score was calculated in relation to a baseline assessment. Good outcome was defined as a modified Rankin Scale score ≤2 at 90 days. Predictive values of clinical improvement and adjusted OR to predict good outcomes were assessed in the whole cohort and the subgroup of patients with posterior circulation stroke (n=166). Results Good outcome was achieved in 656/1666 patients (39%) overall. Percentage improvements both at the end of MT and at 24 hours predicted good outcome, with higher predictive capacity at 24 hours (C-statistic, 0.85 vs 0.73, p 30% cut-off point at the end of MT, and 69% and 84% for the >50% cut-off point at 24 hours, respectively. The adjusted OR for good outcome was 5.8 (95% CI 4.2 to 8.1) and 12.9 (95% CI 9.7 to 17.1), respectively. In patients with posterior circulation stroke, the predictive value of the improvement at 24 hours was similar (C-statistic 0.90). Conclusion Clinical improvement of patients within 24 hours of MT is a reliable and robust predictor of long-term prognosis, including patients with posterior circulation occlusions.