Effect of Known Atrial Fibrillation and Anticoagulation Status on the Prehospital Identification of Large Vessel Occlusion

Introduction: The Cincinnati Prehospital Stroke Severity scale (C-STAT), Los Angeles Motor Scale (LAMS), Rapid Arterial Occlusion Evaluation (RACE) score, and Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scales were designed to aid emergency responder identification of patients with stroke related to large vessel occlusion (LVO). We hypothesized that the addition of a known history of atrial fibrillation (AF) without anticoagulation to currently used scales would improve LVO detection. Methods: Medical records of patients admitted to a Comprehensive Stroke Center with acute ischemic stroke in 2014-2015 were reviewed. LVO identification using the C-STAT, LAMS, RACE, and FAST-ED scores and the AF variable were compared using univariable analyses. The areas under the receiver operating curves (AUCs) were then compared for each score, the AF variable, and each score with the addition of the AF variable. Results: The sample included 233 patients without and 188 patients with an LVO. A history of known AF, history of AF with no anticoagulation, and the C-STAT, LAMS, RACE, and FAST-ED scores were each associated with LVO in univariable analyses. The AUCs for C-STAT, LAMS, RACE, and FAST-ED were similar. The addition of the known AF and no anticoagulation variable did not appreciably change these AUCs. Conclusion: Although known AF with no anticoagulation was associated with LVO in patients with acute ischemic stroke, this historic feature did not improve the accuracy of existing LVO detection scales.