ThP8.10 - Diagnostic accuracy of aortic dissection detection risk score and D-dimer to rule out aortic emergencies in the emergency department – outcomes from a multicentre study

Abstract Background Acute aortic syndromes (AAS) are rare but potentially fatal vascular emergencies affecting the aorta, including aortic dissection, penetrating aortic ulcers, intramural haematoma and occasionally aortic aneurysm rupture. The variety of presentations can make it difficult to decide which patients should have definitive computerised tomography aortogram (CTA) imaging. This study aims to evaluate the diagnostic accuracy of the aortic dissection detection risk score (ADD-RS) combined with D-dimer to rule out AAS in the emergency department. Methods This retrospective cohort study involved two centres. Results of patients who had CTAs between 1st March 2020 – 31st March 2022 were reviewed. Patient data including demographics and laboratory results were logged from day of presentation. Results A total of 435 CTAs were requested. Patients with diagnosis of AAS had higher mean total ADD-RS (1.6 vs 1.0, P<0.05) and higher mean D-dimer (8,836 vs 1,462ng/mL, P<0.05). The use of ADD-RS≤1/normal D-dimer had sensitivity of 100.0% and specificity of 27.9%. Negative predictive value (NPV) was 100%. In this cohort, there were no false negatives. Conclusion This study appears to support the implementation of a new guideline in these departments that incorporates ADD-RS and D-dimer to aid deciding next steps for suspected AAS. In this cohort ADD-RS ≤1 and negative D-dimer (<500ng/mL) had high sensitivity, and low failure rate and could have prevented at least 70 and up to 229 patients from receiving unnecessary radiation. The results suggest that in low-risk patients, with ADD-RS≤1/negative D-dimer, AAS can be safely ruled out. New guidelines could prevent patients receiving unnecessary radiation, contrast induced nephropathy and reduce burden of stretched emergency departments.