Diagnostic performance and optimal cut-off values of cardiac biomarkers for predicting cardiac injury in carbon monoxide poisoning

OBJECTIVE: This study aimed to compare the diagnostic performance of cardiac biomarkers and to evaluate the optimal cut-off values for echocardiographic cardiac injury prediction in patients with carbon monoxide (CO) poisoning. METHODS: This retrospective observational cohort study included adult patients with acute CO poisoning. Patients who did not undergo transthoracic echocardiography, which was used to define patients with cardiac injury (ejection fraction <55%), were excluded. The area under the curve was used to evaluate diagnostic performance for cardiac injury prediction. Mann-Whitney U, chi-square, and Fisher exact tests were used to analyze data. RESULTS: After excluding the 27 patients who did not undergo echocardiography, 114 patients were included in the study. Fifteen (13.2%) patients had cardiac injury. The area under the curve values for the B-type natriuretic peptide, creatine kinase-myocardial band, and troponin I were 0.711 (95% confidence interval [CI], 0.527–0.895; P=0.011), 0.766 (95% CI, 0.607–0.926; P=0.001), and 0.801 (95% CI, 0.647–0.955; P<0.001), respectively, with optimal cut-off values of 330 pg/mL, 10.1 ng/mL, and 0.455 ng/mL, respectively. The sensitivity, specificity, and positive and negative predictive values of troponin I were 67%, 91%, 53%, and 95%, respectively. CONCLUSION: Troponin I showed the best diagnostic performance for predicting cardiac injury in patients with CO poisoning. A cut-off value of 0.455 ng/mL appeared optimal for cardiac injury prediction. However, further studies on cardiac biomarkers and other diagnostic tools in CO poisoning are needed given the low sensitivity of troponin I.