Both cTnI and cTnT are cardiac specific, rapidly released after injury, remain in circulation for several days, are normally in low concentration in serum or plasma, and can be rapidly assayed at relatively low cost.
Currently, cTnI and cTnT are considered the best markers in diagnosing acute cardiac syndrome (ACS). Either protein can be assayed to detect an AMI or other myocardial injury. These markers are especially helpful when the patient with chest pain and symptoms of an AMI does not have a diagnostic ECG. cTnI and cTnT should be considered equal in their performance. cTnI is more common (offered by more vendors) but both markers perform in a nearly identical fashion.
Cardiac troponin levels are used in risk stratification for a patient with chest pain who is not diagnosed with an AMI at presentation. Elevations of cardiac troponins are especially significant when other markers are normal. These elevations predict higher risk of severe cardiac events in the coming month. In other patients with ACS, troponin elevations identify those who are at risk for cardiac events for up to six months.