Introduction: Large vessel occlusion (LVO) triage scales facilitate prehospital bypass to endovascular centers, avoiding time consuming inter-hospital transfers. However, there are concerns that current scales lack specificity when used by paramedics, leading to erroneous bypass. The 3-step ACT-FAST Algorithm was designed for high specificity and reliability. First, arm fall to stretcher <10s is assessed, followed by severe aphasia (if right arm weak) or abnormal shoulder tap response for gaze/neglect (if left arm weak), followed then by questions regarding endovascular eligibility. We prospectively validated the new algorithm with paramedics.
Methods: Over 8 months, paramedics bringing suspected stroke or endovascular transfers to the Royal Melbourne Hospital assessed deficits contemporaneously with stroke doctors. For the first 100 patients (Phase 1), paramedics completed an assessment allowing derivation of several scales: ACT-FAST (exam steps), RACE, LAMS and FAST-ED. For remaining patients (Phase 2) paramedics scored only the ACT-FAST Algorithm with eligibility questions. LVO was defined as ICA/M1 occlusion on CTA with NIHSS ≥6 (AHA guidelines).
Results: A total of 142 patients (29 LVO) were included. Table 1 compares scales in Phase 1. ACT-FAST showed a trend towards highest accuracy compared with other scales. In Phase 2, the full ACT-FAST Algorithm had 83.3% sensitivity and 100% specificity in identifying LVO accepted for endovascular treatment. Agreement on ACT-FAST classification between paramedics and doctors was excellent (kappa = 0.93).
Conclusion: ACT-FAST combines the simplicity of a 3-step algorithm with items optimized for paramedic usability to create a simple LVO identification tool. Initial prospective validation shows excellent reliability and trends towards increased accuracy for LVO recognition compared to other scales. Future research will focus on implementing ACT-FAST in Victoria to determine efficacy of LVO bypass.