Abstract TP191: Prehospital Implementation of the FAST-ED Score and Its Relationship to Large Vessel Occlusion Detection

Background: Large vessel occlusion (LVO) strokes are among the most severe forms of ischemic stroke, requiring rapid identification and transfer to thrombectomy-capable centers for optimal outcomes. The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) score, derived from the NIH Stroke Scale, has shown promise in identifying LVOs. However, most prior studies assessed FAST-ED retrospectively or in hospital settings. This study evaluates the real-time use of FAST-ED by emergency medical services (EMS) personnel in San Diego County and its effectiveness in predicting LVOs during prehospital care. Methods: This observational study analyzed data collected from January 1 to June 30, 2024, involving EMS-transported patients with suspected stroke across San Diego County. Following standardized training, EMS providers calculated the FAST-ED score during field assessment for patients meeting stroke protocol criteria. Data from seven receiving stroke centers were collected, including FAST-ED scores, clinical outcomes, and confirmed LVO status via imaging. These data were de-identified and analyzed by the local EMS authority to evaluate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the FAST-ED score in identifying LVOs. Results: Among patients assessed, the FAST-ED score demonstrated a high NPV, supporting its utility in effectively ruling out LVOs in the field. While higher FAST-ED thresholds (≥6) were associated with improved PPV, lower score thresholds yielded more false positives, which could lead to overtriage to comprehensive stroke centers. Nonetheless, the tool provided EMS personnel with a standardized, rapid method to assess stroke severity and support early triage decisions in a geographically diverse region with variable access to thrombectomy-capable centers. Conclusions: Implementation of the FAST-ED score by EMS providers in the prehospital setting offers valuable support in identifying and ruling out LVOs, particularly in regions like San Diego County with complex transport logistics. While the tool enhances early stroke severity assessment, its moderate PPV suggests it should be integrated with other clinical findings or triage protocols rather than used as a sole determinant for transport destination. Continued refinement, including regional threshold adjustments and integration with EMS technologies, may enhance its effectiveness and optimize prehospital stroke triage systems.