D-dimer/troponin ratio in the differential diagnosis of acute pulmonary embolism from non-ST elevation myocardial infarction.

Background/Aims: The aim of this study was to investigate useful cardiac biomarkers in the differential diagnosis of acute pulmonary embolism (APE) with troponin elevation from acute non-ST elevation myocardial infarction (NSTEMI).

Methods: A total of 771 consecutive NSTEMI patients with D-dimer measurements and 90 patients with troponin-I (TnI) elevation out of 233 APE patients were enrolled, and cardiac biomarkers were compared.

Results: D-dimer elevation was noted in 382 patients with NSTEMI (49.5%), and TnI elevation was noted 90 out of 233 APE patients (38.6%). Unnecessary coronary angiography was performed in 10 patients (11.1%) among 90 APE patients with TnI elevation. D-dimer was significantly elevated in APE than in NSTEMI (9.9 ± 11.6 mg/L vs. 1.8 ± 4.3 mg/L, p < 0.001), whereas TnI was significantly elevated in NSTEMI (22.4 ± 41.5 ng/mL vs. 0.7 ± 1.4 ng/mL, p < 0.001). D-dimer/TnI ratio was significantly higher in APE than in NSTEMI (50.6 ± 85.3 vs. 1.6 ± 5.7, p < 0.001). On receiver operation characteristic curve analysis, the optimal cut-off value for differentiating APE from NSTEMI was 1.12 mg/L for D-dimer (sensitivity 81.1%, specificity 70.2%), 0.72 ng/mL for TnI (sensitivity 80.6%, specificity 78.9%), and 1.82 for D-dimer/TnI ratio (sensitivity 93.3%, specificity 86.6%).

Conclusions: D-dimer/TnI ratio would be a simple and useful parameter for differentiating APE with cardiac troponin elevation from NSTEMI. Optimal cardiovascular imaging to identify APE should be considered in patients with D-dimer/ TnI ratio > 1.82 before performing coronary angiography to avoid unnecessary invasive procedure.