Myocardial injury after off-pump coronary artery bypass grafting operation

Objective: Perioperative myocardial ischemia is less pronounced in off-pump coronary artery bypass (OPCAB) compared to on-pump coronary artery bypass; however, the threshold over which the postoperative release of cardiac troponin I (cTnI) release and creatine kinase-MB (CK-MB) after OPCAB should be considered clinically relevant is unknown. The study was designated to evaluate if perioperative myocardial damage, measured by means of postoperative release of cTnI and CK-MB, has an influence on short- and mid-term outcome after OPCAB operations. Methods: Two hundred and sixty-one unselected patients undergoing OPCAB had cTnI and CK-MB measured preoperatively and nine times postoperatively. Postoperative peak values were evaluated and the 80th percentiles were used to segregate the population into two groups for each marker. The following cut-offs were used: 7.1 ng/dl for cTnI peak and 36.3 ng/dl for CK-MB peak. Results: Patients with cTnI > 7.1 ng/ml (n = 51) and CK-MB > 36.3 ng/ml (n = 48) had a longer mechanical ventilation and ICU length of stay. Nevertheless, hospital mortality did not differ between groups. Survival after 3 years was 92.8 +/- 2.3% and 81.8 +/- 6.2 for patients with postoperative cTnI peak <= 7.1 ng/ml. and > 7.1 ng/ml, respectively (p = 0.003). It was 93 +/- 2.2% and 80 +/- 6.8% for patients with CK-MB <= 36.3 ng/ml and > 36.3 ng/ml, respectively (p = 0.005). Adjusted hazard ratios for mid-term mortality were HR 2.7 (Cl 1-7.6), p = 0.05 for cTnI > 7.1 ng/dl and HR 3.1 (Cl 1-9.1), p = 0.04 for CK-MB > 36.3 ng/ml. Conclusion: Perioperative myocardial damage should not be considered an innocuous event following OPCAB operations since the survival rate over 3 years is significantly worse in patients with the highest postoperative peak release of cTnI and CK-MB. (c) 2007 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.