Combined use of a standardized risk score and d-dimer to rule out acute aortic dissection in the emergency department

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Purpose: Acute aortic dissection (AoD) is a deadly disease requiring timely and accurate diagnosis. The American Heart Association (AHA) has proposed a standardized risk score (SRS) for the diagnosis of AoD, allowing patients stratification in low, intermediate and high risk groups based on predisposing conditions, pain features and physical examination. While d-dimer has been proposed to rule out AoD, is sensitivity is insufficient when applied to all suspected cases. Our aim was to evaluate whether the combination of the SRS and d-dimer could improve the sensitivity to rule out AoD in a large cohort of suspected AoD patients. Methods: Analysis were conducted on a prospective registry of consecutive adult patients evaluated in two EDs for suspected AoD from January 2008 to December 2012. D-dimer testing was performed in enrolled patients and the cutoff to rule out AoD was 500ng/ml or feu/ml. Patients were stratified in the 3 risk groups proposed by the AHA. The definitive diagnosis of AoD was obtained with computed tomography angiography, surgery or autopsy. Results: Amongst 898 enrolled patients (mean age 67 yrs), 164 (18.2%) were diagnosed with AoD. 314 (34.9%) were classified in low, 423 (47.1%) in intermediate and 161 (17.9%) in high risk for AoD. The prevalence of AoD within the groups was 9%, 26% and 40% respectively. D-dimer was falsely negative in 2 of the intermediate and in 2 of the high risk groups. Sensitivity, specificity, predictive value (PV) and likelihood ratio (LR) of d-dimer in each risk group are reported in the table and expressed as % and 95% confidence interval (95% CI). Test characteristics of d-dimer Conclusions: In the low risk group a negative d-dimer ruled out AoD (10% of all patients) with 100% sensitivity and 100% negative PV. In low/intermediate risk group a negative d-dimer ruled out AoD (25% of all patients) with 98.1% sensitivity and 99.1% negative PV thus avoiding secondary imaging tests in one fourth of all patients evaluated for AoD.

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