<scp>SOAR</scp> Study: Southern Outcomes in Aortic Rule‐Out ( <scp>ADvISED</scp> External Validation Study)

BACKGROUND: Acute aortic syndromes (AAS), including aortic dissection, intramural haematoma (IMH), and penetrating atherosclerotic ulcer (PAU), are uncommon but life-threatening causes of chest pain. Computed tomography angiography (CTA) is highly sensitive for AAS but is increasingly overutilised despite low diagnostic yield, exposing patients to radiation, contrast risk, and healthcare cost. The ADvISED rule-out algorithm, combining the Aortic Dissection Detection Risk Score (ADD-RS) with serum D-dimer, has demonstrated high negative predictive value (NPV) in prospective studies but has limited external validation. METHODS: We performed a retrospective cohort study of adult emergency department patients within a tertiary cardiothoracic referral network in southern New Zealand who underwent CTA for suspected AAS between January 2018 and January 2024. Clinical records were reviewed to retrospectively calculate ADD-RS and extract D-dimer results prior to imaging. CTA findings served as the reference standard. The primary outcome was the NPV and failure rate of the ADvISED rule-out algorithm (low ADD-RS [0-1] plus negative D-dimer < 500 ng/mL). RESULTS: Of 1392 CTA studies reviewed, 1000 met inclusion criteria. Forty-one patients (4.1%) were diagnosed with AAS. Among patients with low ADD-RS and negative D-dimer (n = 180), one case of AAS (IMH) was identified, yielding an NPV of 99.4% and a failure rate of 0.6%. No Stanford type A AAS were missed. Most non-AAS diagnoses were non-specific chest pain (45%) or cardiac conditions (20%), with fewer than 1% benefiting from alternative angiographic diagnoses. CONCLUSIONS: In this regional emergency department cohort, the ADvISED rule-out algorithm demonstrated excellent negative predictive value and safely excluded AAS in low-risk patients. External validation in this population supports its use as a clinical decision aid to reduce unnecessary CTA utilisation without compromising patient safety. Prospective implementation studies are warranted to further assess its impact on imaging stewardship and clinical outcomes.