Abstract WP031: Effect of Intravenous Thrombolysis before Mechanical Thrombectomy on Functional Outcomes in Acute Ischemic Stroke: A Single-Center Retrospective Cohort Study

Introduction: Intravenous thrombolysis (IVT) is recommended for acute ischemic stroke (AIS) patients presenting within 4.5 hours of symptom onset. Since 2015, mechanical thrombectomy (MT) has been the standard of care for large vessel occlusions (LVO). While both treatments are often used in eligible patients, the added benefit of IVT prior to MT remains uncertain. It is hypothesized that IVT before MT may enhance reperfusion and improve functional outcomes, though this effect may vary based on vessel size, occlusion location, and timing of intervention. Methods: We conducted a single-center retrospective cohort study of 2,259 AIS patients who underwent MT between 2014 and 2025. Demographic, clinical, and procedural data were extracted from medical records. The primary outcome was 90-day functional status, assessed using modified Rankin Scale (mRS). Secondary outcomes included recanalization rates and symptomatic intracranial hemorrhage (sICH) rates. Continuous variables were reported as means (SD) and categorical variables as proportions. Continuous variables were compared using t tests and categorical variables via chi square. Logistic regression was used to evaluate associations between treatment strategy (IVT+MT vs. MT alone) and outcomes, with unadjusted and adjusted odds ratios calculated (adjusting for age, sex, hypertension, and diabetes). Results: Of 2259 patients who underwent MT (mean age 79.1, 50.7% female), 848 (37.5%) received IVT. The IVT group had higher odds of achieving good functional outcome defined as 90-day mRS of 0-2 (OR 1.18, 95% CI 0.99-1.41, p=0.066). After adjusting for confounders, this finding became statistically significant (aOR 1.36, 95% CI 1.19-1.68, p=0.005). Secondary outcomes include similar recanalization rates (aOR 0.87, 95% CI 0.73-1.04, p=0.127) and marginally lower odds of sICH in the IVT group (aOR 0.69, 95% CI 0.48-1.00, p=0.051). Subgroup analysis revealed that IVT was not associated with favorable functional outcome among medium vessel occlusion (MeVO) patients (OR 0.82, 95% CI 0.52–1.29), whereas in LVO patients IVT nearly doubled the odds of good outcome (OR 1.91, 95% CI 1.14–3.19, p=0.014). There was no significant differential interaction between IVT and the specific vessel occluded. Conclusions: In AIS, the combination of IVT and MT raises the odds of favorable functional outcomes compared to MT alone, especially in patients with LVO compared to MeVO regardless of specific vessel location without increasing sICH risk.