Intravenous thrombolysis for mild stroke: NIHSS 3-5 Versus NIHSS 0-2.

BACKGROUND AND PURPOSE: Studies have shown that mild stroke patients with National Institutes of Health Stroke Scale (NIHSS) score 3-5 but not 0-2 may benefit from the intravenous thrombolysis when compared with antiplatelet therapy. We aimed to compare the safety and effectiveness of thrombolysis in mild stroke with NIHSS score of 0-2 vs. 3-5 and identify the predictors of an excellent functional outcome in a real world longitudinal registry. METHODS: In a prospective thrombolysis registry, we identified patients with acute ischemic stroke who presented within 4.5 hours of symptom onset and had initial NIHSS scores ≤ 5. Demographic data, medical history, pre-stroke medications, imaging data, and laboratory measures were collected. The outcome of interest was modified Rankin Scale score of 0 to 1 at discharge. Safety outcome was evaluated by syptomatic intracrerebral hemorrhage defined as any decline in neurologic status due to hemorrhage within 36 h. Multivariable regression models were performed to explore the safety and effectiveness in the alteplase-treated patients with admission NIHSS 0-2 vs. 3-5 and identify factors independently associated with an excellent functional outcome. RESULTS: Of a total of 236 eligible patients, those with an admission NIHSS score of 0-2 (n=80) had a better functional outcome at discharge compared with NIHSS 3-5 group (n=156) (81.3% vs. 48.7%, adjusted odds ratio [aOR] 0.40, 95% confidential interval [CI] 0.17 - 0.94, P=0.04) without increasing the rate of symptomatic intracerebral hemorrhage and mortality. Non-disabling stroke (Model 1: aOR 0.06, 95%CI 0.01-0.50, P=0.01; Model 2: aOR 0.06, 95% CI 0.01-0.48, P=0.01) and prior statin therapy (Model 1: aOR 3.46, 95% CI 1.02-11.70, P=0.046; Model 2: aOR 3.30, 95% CI 0.96-11.30, P=0.06) were independent predictors of excellent outcomes. CONCLUSIONS: Acute ischemic stroke patients with admission NIHSS 0-2 was associated with better functional outcomes at discharge compared with NIHSS 3-5 within the 4.5-hour time window. Minor stroke severity, non-disabling stroke and prior statin therapy were independent predictors for funcitonal outcomes at discharge. Further studies with large sample size are needed to confirm the findings.