Abstract DP201: Real-World Intravenous Thrombolysis and Imaging Practices in Patients with Unknown Stroke Onset Across Louisiana Certified Stroke Centers

Background and Purpose: The 2019 American Heart Association/American Stroke Association guidelines recommend intravenous thrombolysis (IVT) for patients with unknown time of stroke onset (TSO) who are possibly in window (PIW) for IVT using MRI. We evaluated treatment rates, imaging utilization, and care efficiency among PIW patients at Louisiana-certified stroke centers. Methods: We analyzed quarterly data from 27 certified stroke centers (Q1-Q4 2024). We included patients with an unknown TSO who presented within 4.5 hours of symptom discovery and, therefore, may be eligible for IVT (PIW). Outcomes included IVT treatment rates, imaging modality, door-to-imaging and door-to-needle times, and reasons for non-treatment. Descriptive statistics and trend analyses are reported. Results: Among 996 PIW patients, 59 (5.9%) received IVT. Majority (67.0%) arrived by ground ambulance. NIHSS was documented in 96.1% (median: 6, IQR: 2-14). Imaging used included CT (34.0%), MRI (18.9%), and CTP (15.7%). However, 31.4% had no documented imaging modality. Median door-to-imaging times were 25 minutes for CT, 35 minutes for CTP, and 55 minutes for MRI. Median door-to-needle time was 52 min. The leading reasons for non-treatment were clinical contraindications (38.9%), imaging contraindications (29.8%), and protocol / system barriers (9.6%). Conclusions: IVT treatment rates in PIW patients remain low despite guideline recommendations. Imaging delays, especially with MRI, and system barriers substantially contribute to under-treatment.