Investigation of cardiac markers cut off values in the diagnosis of acute coronary syndrome

Aim: The number of patients applying to the emergency service with acute chest pain complaint are rather high, however most of them are not diagnosed with acute coronary syndrome (ACS). Firstly non-cardiac causes should be excluded to be able to determine true cardiac patients. Troponins are structural proteins of the cardiac muscle, also sensitive and specific molecules of cardiac damage. In this study, we aimed to determine cut off value of Creatine kinase MB (CKMB) test for ACS diagnosis by using cardiac troponin T (cTnT) results and ROC analysis. We also evaluated the combined use of cardiac markers and clinical finding in acute myocardial infarction (AMI) patient management. Material and Method: Laboratory and clinical data, including electrocardiography (ECG) and cardiac markers (cTnT, CKMB levels) of 390 patients applying to emergency service with acute chest pain were retrospectively collected and attempted to develop a strategy using these data. The cases (age: 58.65±13.29) were divided into two groups: first group AMI and second group non-ischemic injury. CKMB levels were measured by the immunoinhibition method in Dimension Xpand Plus (Dade Behring Inc, Newark, USA) chemistry autoanalyzer. The Cardiac T Quantitative Rapid Assay (Roche Diagnostics GmbH, Mannheim, Germany) was used for cTnT measurement. Result: In our study, AMI was detected in 36 of 390 patients (9.2%). In prediction of AMI, the diagnostic specificity and diagnostic sensitivity of CKMB was 92% and 44% for 16 U/L; 86% and 50% for 12 U/L; 79% and 61% for 9 U/L, 63% and 69% for 6 U/L, respectively. The area under the curve for CKMB was 0.72 (SE: 0.055, p <0.001). Conclusion: Although cTnT is the most important marker in early diagnosis of AMI in emergency department, CKMB levels are a reliable marker that should be used together to reduce both false negative and false positives.