The Significance of Cardiac Troponin T to the Diagnosis of Myocardial Damage in Coronary Artery Bypass Grafting

Objective:To investigate the perioperative release of cardiac troponin T(cTnT) and creatine kinase-MB isoenzyme(CK-MB) and their efficacy and differences in diagnosing myocardial injury in coronary artery bypass grafting(CABG).Methods: From Jun.2006 to Oct.2009,in 152 patients,activity of cTnT and CK-MB in serum were analyzed before and after operation at 9 different time intervals.Their mean age was 62.5±20.7(39～80)years old.The average number of graft was 2.7(1～5) per patient,mean CPB time was(113±54) minutes and aortic cross-clamping time was(56±31)minutes.Results: The concentration of cTnT and CK-MB both elevated after aortic cross-clamping release and reached peak(0.49±0.23 μg/L,56.3±28.6 IU/L each other)after 10 hours of cross-clamping release.Five days later of operation,CK-MB resumed to level of preoperation.But cTnT needed 10 days for that.cTnT in 13 patients with perioperative myocardial infarction(PMI) was significantly higher than that of non-PMI during the perioperative period(P0.001) and its peak were 2.97±1.12 μg/L after 10 hours of cross-clamping release.Ten days after operation,it was still higher than the normal level(0.87±0.31 μg/L).Seven of these 13 patients died of PMI after operation.But in non-PMI patients,no one die of cardiac cause.Conclusions:The change of cTnT and CK-MB is the similar at the preceding stage after coronary artery bypass grafting.But the time which cTnT is higher than the normal level is longer than that of CK-MB.Because of the better sensitivity and specificity than CK-MB,cTnT is the more reliable biochemical marker to diagnose myocardial damage and to predict PMI and the prognosis of coronary artery bypass grafting.