Validation of the diagnostic utility of D-dimer measurement in patients with acute aortic syndrome.

OBJECTIVE: The objective of this study was to evaluate the validity of D-dimer measurements for the diagnosis of acute aortic syndrome in patients admitted to hospital with acute chest pain.
METHODS: A retrospective observational study design was used. Consecutive patients ( n=887) admitted to a tertiary hospital with acute chest pain (acute aortic syndrome, 123; acute pulmonary embolism, 29; and other disease, 735) from the emergency department between January 2011 and April 2014 were assessed to validate the diagnostic value of D-dimer measurements.
RESULTS: The D-dimer level was significantly increased in patients with acute aortic syndrome (median (interquartile range) 4.9 (2.0-17.4) µg/ml) compared with control patients (median (interquartile range) 0.6 (0.3-1.4) µg/ml; p<0.001). At a cut-off point of 0.5 μg/ml, the sensitivity for acute aortic syndrome was 0.97 (95% confidence interval 0.92-0.99) and was similar to that for acute pulmonary embolism (0.97 (0.82-0.99)). The age-adjusted D-dimer cut-off point, defined as age × 0.01 μg/ml in patients ⩾50 years, successfully reduced the number of false-positive diagnoses by 13%, while still retaining a high sensitivity (0.96 (0.91-0.99)). The five false-negative diagnoses of acute aortic syndrome included three patients with intramural haematoma, one patient with a penetrating aortic ulcer and one patient with an impending aortic rupture. A combination of probability assessment and the D-dimer approach reduced the number of false-negatives from five patients to two patients.
CONCLUSIONS: This study demonstrated that the D-dimer test can distinguish acute aortic syndrome from other diseases presenting with acute chest pain with high sensitivity and modest specificity. Using the D-dimer approach presents limitations with some subtypes of acute aortic syndrome, such as intramural haematoma.