Predictors of major improvement after intravenous thrombolysis in acute ischemic stroke

Background: Intravenous thrombolysis improves outcomes of stroke patients. The immediate response to thrombolysis is variable and few studies attempted to identify predictors of major neurological improvement (MNI) 24h following thrombolysis. Our objective is to determine predictors of MNI 24h following thrombolysis. Methods: We reviewed the prospective database of patients treated through our telestroke network and at our institution between November 2008 and June 2012. We included all patients who received IV t-PA and had a 24-h NIHSS score available. Similar to previous studies, we defined MNI as a reduction in NIHSS score by 8 points, or a score of 0 or 1 at 24h. Demographics, risk factors, time to treatment, and clinical and laboratory data, were compared between MNI present or absent. Baseline predictors were compared using t- and Fisher's exact tests, and outcomes using multivariate logistic regression analysis. Results: Out of 316 patients, 306 had 24-h NIHSS scores and 38% of them experienced MNI. Patients with MNI were less likely to be older than 80years (16% vs. 29%, p = 0.008) and to have atrial fibrillation (9% vs. 24%, p = 0.001) compared to those without; we found no other predictors of MNI. After adjusting for baseline demographics and risk factors, age less than 80years (OR = 1.9, 95% CI 1.1-3.6) and absence of atrial fibrillation (OR = 3.0, 95% CI: 1.4-6.2) predicted MNI. Conclusion: Major neurological improvement within 24h after thrombolysis is more likely in younger patients and those without atrial fibrillation.