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

BACKGROUND

Cardiac troponin I (cTnI) 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 cTnI, 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%. CTnI 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 cTnI and cTnT levels and CKMB were statistically identified for all variables.

RESULTS

The best cutoff value for cTnI was 8.35 micrograms/l. The patients were grouped by the ECG findings and maximal slopes of cTnI postoperatively (group I: unchanged ECG and cTnI < 8.35 micrograms/l, n = 38; group II: unchanged ECG and cTnI > 8.35 micrograms/l n = 6; group III: Q-wave in ECG and cTnI > 8.35 micrograms/l, n = 4). Baseline serum concentrations of cTnI were in the normal range, and significantly increased after surgery with a peak 24h after the operation. Maximal slopes of cTnI ranged in group II between 9.1 and 18.0 micrograms/l, and in group III between 35.9 and 88.8 micrograms/l. There was strong concordance between maximum cTnI, cTnT (p < 0.0001) and CK-MB levels (p = 0.003). First cTnI levels immediately post-op correlated with the maximum cTnI levels during the postoperative course (p = 0.009).

CONCLUSIONS

CTnI after minimal invasive surgery shows a characteristic pattern with a maximum at 24h after the operation. The measurement of postoperative biochemical marker concentrations, specially cTnI, reflects myocardial injury incurred during the procedure. It is an accurate method for confirming or excluding a perioperative myocardial injury diagnosis after OPCAB surgery.