Sensitivity and specificity of troponin t in diagnosis of acute myocardial infarction

Abstract

Lately, in the diagnosis of acute myocardial infarction (MI), special attention is paid to the study of small molecular weight proteins, representing the strucrutal components of cardial muscle controctile proteins, such as cardial troponin T (cTnT). Therefore, the aim of this study was to determine and compare the specificity and sensitivity of cTnT myoglobine and the activity of standard tested enzymes such as: creatine kinase (CK), CK MB isoenzymes and lactic delytrogenase (LDH) in early diagnosis of acute MI. The study concerned the four groups of patients. The first group consisted of healty blood donors (n = 105), the second of patients with verified acute MI (n = 30), the third of a patients with polytrauma (n = 30), and the fourth of patients with cardiovascular diseases with no proved MI (n = 30). For the determination of cTnT level, the commercial Eleccys Troponin T STAT test was used (third generation), Boehringer Mannheim company, based on ECLIA (tehnique of electrochemical luminiscent analysis), designated for the work with automated analysis Elecsys 2010. The concentration of myoglobine (Mi) was determined by immunoturbiometric method, while the activity of other enzymes was determined by the standard IFCC methods with biochemical analyser HITACHI 911, Boehringer Manheim, and with original test reagents. The reference values of blood donor individuals found in the blood ranged from 0.01 to 0.028 ng/mL. In the group of patients with acute MI, biochemical markers (cTnT, CK, CK MB, Mi and LDH) were determined as soon as the material was received by the 24 h service and 4, 8 16, 24, 48, 72, 96, 120, 144, 168, 192 and 216 hours later. In patients with polytrauma the markers were tested 8 hours after surgery and in patients with other cardiovascular deseases with non documented acute MI immediattely after admission, and 4, 8, 16 and 24 hours later. The level of cTnT in patients with proved acute MI was increased at the first testing after admission. The highest values were found at hour 16, gradually declining thereafter, but maintaining above the higher control level in the next 216 hours after admission. In patients with cardiovascular diseases and non documented acute MI the level of cTnT was unchanged. Comparison of results of these two groups of patients showed statistically significant differences in cTnT levels in patients with acute MI during all tested time intervals. In the group of patients with polytrauma only the value of cTnT was within the normal level. Diagnostic precision of tested cardiac markers was also tested by ROC analysis. According to the data obtained, only cTnT exhibited statistically significiant diagnostic precision immediately after the admission of patients with the following calculated ROC AUC: 0.855 for cTnT, 0.716 for CK, 0.503 for CK MB and 0.552 for LDH, respectively. According to the presented data, it can be concluded that cTnT was the most specific and the most sensitive marker in the diagnosis of acute MI.