CARDIAC TROPONIN-I PLASMA-LEVELS FOR DIAGNOSIS AND QUANTITATION OF PERIOPERATIVE MYOCARDIAL DAMAGE IN PATIENTS UNDERGOING CORONARY-ARTERY BYPASS-SURGERY

Objective: The definition of a reliable and generally accepted diagnos tic standard for perioperative myocardial damage is desirable. Cardiac troponin I (cTnI) is highly specific for myocardial tissue and can be measured rapidly. The aim of our study was to evaluate the diagnostic potential of cTnI for myocardial lesions in patients undergoing coron ary artery bypass surgery (CABG). Methods: A total of 119 patients wit h diffuse coronary artery disease were operated on using blood cardiop legia. Serial blood samples drawn before and after surgery were analyz ed for the activity of creatine kinase MB isoenzyme (CKMB) and the con centrations of CKMB mass, cardiac troponins T and I. On the basis of t he biochemical results (except cTnI) and the findings of electrocardio graphy/echocardiography, patients were classified and cTnI was studied for each group separately: group I, minor myocardial damage; group II , non-transmural infarction; group III, transmural infarction; and gro up IV, preoperative non-transmural infarction. Results: In 87 patients of group I (73.1%) cTnI levels remained low; 19 patients (16.0%) were assigned to group II, 8 patients (6.7%) to group III, and 5 patients (4.2%) to group IV. For discrimination of patients without and with pe rioperative myocardial infarction (PMI) by one cTnI determination the use of cutoff values of 6.5 ng/ml at 8 h, 9.8 ng/ml at 12 h, and 11.6 ng/ml at 24 h after aortic unclamping resulted in a diagnostic efficie ncy of 88, 94 and 98%. Especially, a cTnI value at 24 h had a sensitiv ity of 100% and a specificity of 97%. Cardiac troponin levels at 24 h were found to correlate closely with the well-recognized 2-48 h area-u nder-the-curve (P < 0.0001; R = 0.993), making serial determinations u nnecessary. Conclusions: cTnI qualifies as a marker for diagnosis of P MI and quantitation of the amount of myocardial damage, because of the availability of a quick diagnostic test with high specificity, the hi gh diagnostic efficiency, and especially the sufficient information ga ined by a single determination 24 h after aortic unclamping. (C) 1998 Elsevier Science B.V.