FLUOROENZYMOMETRIC METHOD TO MEASURE CARDIAC TROPONIN-I IN SERA OF PATIENTS WITH MYOCARDIAL-INFARCTION

The aim of our study was to evaluate the clinical relevance of serum t roponin I (TnI) as a marker of ischemic myocardial injury by using an automated fluoroenzymometric assay. The reference range for serum TnI was established by measuring serum TnI concentrations in blood from 75 healthy donors. The concentration was then compared with serum creati ne kinase (CK) activity, CK-MB mass, and myoglobin concentrations in 2 0 patients with myocardial infarction diagnosed according to the WHO c riteria, 20 patients with chest pain of nonischemic origin, 9 patients with unstable angina, 11 with stable angina, 11 patients with chronic muscular diseases, 6 patients with muscular trauma without chest cont usion, and 13 patients with chronic renal disease. We found that: (a) 99% of the blood donors had TnI concentrations <0.26 mu g/L (detection limit of the assay in our study); (b) TnI values in acute myocardial infarction (AMI) patients 4 h after onset of chest pain showed a sensi tivity of 0.769 and a specificity of 1.0 at a decisional concentration for AMI of 1 mu g/L, even in the presence of severe skeletal muscle i njuries or renal diseases; (c) the increase in TnI concentrations afte r infarction (interquartile range 3.25-6 h) and the peak occurred late r (interquartile range 11.5-24 h) than the rise found in myoglobin and CK-MB, but the increase persisted much longer (>96 h); (d) receiver-o perating characteristic curve analysis showed the high diagnostic accu racy of TnI in diagnosing AMI even in patients in whom traditional bio chemical markers are adversely influenced by underlying clinical situa tions.