Patterns and diagnostic value of cardiac troponin I vs. troponin T and CKMB after OPCAB surgery

Background: Cardiac troponin I (cTnl) has been shown to be a specific marker for myocardial injury in cardiac surgery. The object of this prospective study was to determine the patterns and kinetic and diagnostic value of cTnl, cardiac troponin T (cTnT), and creatine kinase MB (CKMB) activity after minimally invasive coronary revascularization using an octopus device on the beating heart (OPCAB). Methods: 48 patients (33 male/15 female, mean age 68.3 +/- 8.7 years) underwent their first elective OPCAB surgery with median sternotomy without mortality. The mean number of grafts was 2.0 +/-0.8 per patient. Preoperative mean ejection fraction was 56.6% +/- 14.9%. CTnl and T levels, total creatine kinase (CK) and CK-MB activity in the serum were measured before operation, at arrival at the ICU, and 6, 12, 24, 48 and 120 hours afterward. Serial 12-lead ECGs were recorded preoperatively and at days 1, 2 and 5. The relationship between perioperative data and postoperative cTnl and cTnT levels and CKMB were statistically identified for all variables, Results: The best cutoff value for cTnl was 8.35 mug/l. The patients were grouped by the ECG findings and maximal slopes of cTnl postoperatively (group I: unchanged ECG and cTnl<8.35 <mu>g/l, n=38; group II: unchanged ECG and cTnl >8.35 mug/l n = 6; group III: Q-wave in ECG and cTnl >8.35 mug/l, n=4). Baseline serum concentrations of cTnl were in the normal range, and significantly increased after surgery with a peak 24 h after the operation. Maximal slopes of cTnl ranged in group I between 9.1 and 18.0 mug/l, and in group III between 35.9 and 88.8 mug/l. There was a strong concordance between maximum cTnl, cTnT (p<0.0001) and CK-MB levels (p=0.003). First cTnl levels immediately post-op correlated with the maximum cTnl levels during the postoperative course (p=0.009). Conclusions: CTnl after minimal invasive surgery shows a characteristic pattern with a maximum at 24 h after the operation. The measurement of postoperative biochemical marker concentrations, specially cTnl, reflects myocardial injury incurred during the procedure. It is an accurate method for confirming or excluding a perioperative myocardial injury diagnosis after OPCAB surgery.