New biochemical markers in the assessment of minor myocardial damage in critically ill patients

UNLABELLED: The diagnosis of acute myocardial infarction (AMI) and unstable angina is based on typical clinical signs, electrocardiogram (ECG) changes, and serial measurements of characteristic serum enzymes, especially troponins. Today, newer biochemical markers are used in assessing these conditions, as well as minor myocardial damage (MMD). AIM: The aim of this study was to determine the existence of MMD by the analysis of new biochemical markers including cardiac troponin T (c-TnT), troponin I (c-TnI), CK-MB activity (CK-MBact), CK-MB mass (CK-MBmass), a conventional marker of total creatine kinase (CK), and 12-lead ECG monitoring in two groups of critically ill patients admitted to the intensive care unit (ICU). Group 1 (n=52) consisted of the patients with heart failure, unexplainable hypotension, chronic obstructive pulmonary disease in acute exacerbation, acute severe pancreatitis, sepsis, pulmonary embolism, diabetes with complications, liver cirrhosis, and tachycardia >120/min who suffered chest discomfort without evident ECG signs of AMI. Group 2 consisted of patients (n=73) with acute gastrointestinal bleeding, poisoning, and miscellaneous conditions without chest discomfort or ECG signs of AMI. RESULTS: Of the 52 critically ill patients, 21.2% were positive for troponin T and 11.5% for troponin I. Group 1 patients showed a prevalence of elevated total CK (28.8%), CK-MBact (7.7%), and CK-MBmass (32.7%). In group 2, positive troponin I was found in 19.7% of patients, troponin T was negative (0.00%), with elevated total CK (23.9%), CKMBact (7.0%), and CK-MBmass (2.3%). The mean concentrations of c-TnT, c-TnI, total CK, CK-MBact, CK-MBmass were higher in group 1 than in group 2, however, without statistical significance. The best positive correlation was recorded between CK-MBact and CK-MBmass (r=0.63). The c-TnI showed best discrimination and accuracy in the assessment of MMD under the ROC curves surface (0.84), while the accuracy was low for all other markers analyzed. Discrimination and accuracy were moderate for all markers analyzed. DISCUSSION AND CONCLUSION: CK-MBact (92.3%) showed the highest specificity, followed by c-TnI (88.5%) and c-TnT (75.6%). The sensitivity was low for all markers analyzed. Concerning specificity, CK-MBact proved to be the best biologic marker for the assessment of MMD, followed by c-TnI and c-TnT. Correct clinical assessment according to marker accuracy and discrimination can be achieved by use of c-TnI, however, with a moderate degree of accuracy and discrimination for the detection of MMD in critically ill patients admitted to ICU.