Determinants of ELISA D-Dimer sensitivity for unstable angina pectoris as defined by coronary catheterization

Unstable angina pectoris is associated with elevated D-dimer levels. However, the operating characteristics (sensitivity, specificity, positive and negative predictive value) of the D-dimer assay for the diagnosis of coronary artery disease (CAD) are unknown. Using a prospective, observational design, we collected blood from 54 patients with unstable angina pectoris at admission and assayed for ELISA D-dimer levels. The sensitivity, specificity, and negative and positive prediction values for angiographically determined coronary artery disease were calculated at multiple discriminate levels. All patients underwent coronary catheterization. A statistically significant correlation was noted between ELISA D-dimer levels and age, male sex, hypertension, use of β-blocker, fibrinogen levels and catheterization findings. No correlation was noted between ELISA D-dimer levels and degree of the coronary artery disease. Best results were provided at a discriminate level of 270 ng/ml, with sensitivity 70%, negative predictive value 72%, and overall accuracy 67%. All discriminate levels, however, provided values too low for diagnosis. In conclusion, ELISA D-dimer assay is a non-sensitive, non-specific test for coronary artery disease as defined by coronary catheterization. However, the assay adds information regarding the severity of disease in patients presenting with acute coronary syndrome.