Abstract
OBJECTIVE: Acute aortic syndrome (AAS) refers to a group of life-threatening cardiovascular emergencies that require computerised tomographic aortography (CTA) for definitive diagnosis. However, there is currently no validated risk-stratification tool for AAS in low or intermediate risk patients using the aortic dissection detection risk score (ADD-RS). This study evaluated the efficacy of d-dimer in low or intermediate risk patients who underwent CTA for suspected AAS. METHODS: This retrospective, cross-sectional study included all atraumatic thoracic CTAs performed at Auckland City Hospital (Aotearoa New Zealand) between 2009 and 2019 for adults with suspected AAS presenting to the emergency department (ED). Pre-test probability for AAS was determined using the ADD-RS. The sensitivity and negative predictive value (NPV) of a negative d-dimer (< 500 ng/mL) for ruling out AAS in low or intermediate risk patients (ADD-RS ≤ 1) were calculated. Trends in d-dimer requests over time were also analysed. RESULTS: d-dimers were assessed in 181 low or intermediate risk patients with thoracic CTAs. Negative d-dimer had a sensitivity of 100% (95% CI: 66%-100%) and NPV of 100% (95% CI: 97%-100%) for ruling out AAS. There was a significant rise in the annual number of d-dimer requests among patients who underwent CTA scans (p = 0.0059). Significantly more of these requests returned negative values (p = 0.0036), while the number of positive results (≥ 500 ng/mL) remained unchanged (p = 0.15). CONCLUSIONS: Our findings suggest that d-dimer < 500 ng/mL may be used to forgo unfavourable CTA scans in low or intermediate risk patients within our small AoNZ cohort in whom AAS is suspected.