Thrombolysis in Patients With Mild Ischemic Stroke: A Comparative Effectiveness Study From the Norwegian Stroke Registry.

BACKGROUND: Intravenous thrombolytic therapy (IVT) is recommended for patients with acute ischemic stroke (AIS) and disabling deficits, regardless of National Institutes of Health Stroke Scale (NIHSS) score. The benefit of IVT in patients with mild AIS was, however, not documented in recent trials. The aim of this study was to evaluate the effectiveness of IVT in mild AIS in a nationwide registry-based study. METHODS: AIS patients from the Norwegian Stroke Registry (2016-2022) with a National Institutes of Health Stroke Scale (NIHSS) score ≤ 5 at admission were included. Using 1:1 propensity score matching, 1736 IVT-treated patients were matched with 1736 controls. Primary outcome was excellent functional outcome (modified Rankin Scale [mRS] score 0-1) at 90 days. Secondary outcomes included mRS 0-2, a favorable mRS shift (range 0-6), and death within 28 and 90 days. Data on symptomatic intracerebral hemorrhage (sICH) were available only for the IVT group. RESULTS: At 90 days, 68.4% of IVT-treated patients and 61.2% of controls achieved mRS 0-1 (OR 1.39; 95% CI 1.20-1.60). IVT was associated with a higher probability of achieving excellent functional outcome in patients with NIHSS 4-5 (OR 1.53; 95% CI 1.06-2.21) and NIHSS 2-3 (OR 1.64; 95% CI 1.32-2.03), but not NIHSS 0-1 (OR 1.14; 95% CI 0.89-1.44). No significant differences in overall mortality were observed. SICH occurred in 3.7% of IVT-treated patients. CONCLUSION: IVT was associated with favorable functional outcomes for mild AIS, but not in patients with NIHSS 0-1.