Cardiac markers used in the detection of myocardial injury

OBJECTIVE: Activities of total creatine kinase and its isoform creatine kinase are usually significantly elevated in patients with myocardial or skeletal muscle injury as well as in those with renal failure. The purpose of this study was to compare findings for creatine kinase mass, cardiac troponin T and cardiac troponin I with those of creatine kinase and creatine kinase MB activity.

METHODS: Blood samples from 118 patients were studied. Fifty eight patients had significantly elevated creatine kinase activity (39 with and 19 without clinically proven myocardial injury or infarction) and 60 were normal controls. The sensitivity, specificity, positive and negative predictive values were calculated for all markers.

RESULTS: Cardiac troponins had 100% sensitivity and negative predictive value, for myocardial injury, as compared with 92% and 96% for creatine kinase activity and 96% and 97% for creatine kinase-mass. Cardiac TnI had the highest specificty and positive predictive value (99% and 98%) as compared with cardiac troponin T (96% and 93%), creatine kinase-mass (92% and 86%) and creatine kinase activity (89% and 80%).

CONCLUSION: Cardiac troponins, especially cardiac troponin T, have very high sensitivity, specificity and predictive value for myocardial injury.