Predictor of 90-day functional outcome after mechanical thrombectomy for large vessel occlusion stroke: NIHSS score of 10 or less at 24 hours

OBJECTIVE Mechanical thrombectomy is the established treatment for acute ischemic stroke due to large vessel occlusion (LVO). The authors sought to identify early predictors of a favorable outcome in stroke patients treated with mechanical thrombectomy. METHODS Consecutive patients with ischemic stroke due to LVO who underwent mechanical thrombectomy at a Comprehensive Stroke Center in the US between 2016 and 2018 were retrospectively reviewed. Demographics, stroke and treatment characteristics, as well as functional outcome at 90 days were collected. Clinical predictors of 90-day functional outcome were assessed and compared to existing indices for prompt neurological improvement. Analyses of area under the receiver operating characteristic curve were performed to estimate the optimal thresholds for absolute 24-hour and delta (change in) National Institutes of Health Stroke Scale (NIHSS) scores for functional outcome prediction. RESULTS A total of 156 patients (median age 71.5 years) underwent 159 mechanical thrombectomies. The M1 segment of the middle cerebral artery was the most frequent site of occlusion (57.2%). The median NIHSS score before thrombectomy was 18 (IQR 14-24). A postthrombectomy Thrombolysis in Cerebral Infarction score of 2B or 3 was achieved in 147 procedures (92.4%). The median NIHSS score 24 hours after thrombectomy was 14 (IQR 6-22). Good functional outcome at 90 days (modified Rankin Scale score 0-2) was achieved in 37 thrombectomies (23.9%). An absolute 24- hour NIHSS score = 10 (OR 25.929, 95% CI 8.448-79.582, p < 0.001) and a delta NIHSS score = 8 between baseline and 24 hours (OR 4.929, 95% CI 2.245-10.818, p < 0.001) were associated with good functional outcome at 90 days. The 24-hour NIHSS score cutoff of 10 outperformed existing indices for prompt neurological improvement in the ability to predict 90-day functional outcome. CONCLUSIONS An NIHSS score = 10 at 24 hours after mechanical thrombectomy was independently associated with good functional outcome at 90 days.