The association of elevated creatine kinase-myocardial band on mortality after coronary artery bypass grafting surgery is time and magnitude limited

OBJECTIVE: The joint European Society of Cardiology and American College of Cardiology consensus statement on myocardial necrosis after revascularization stated that any amount of myocardial necrosis as detected by cardiac enzymes should be labeled a myocardial infarct. However, it also stated that more data collection is necessary to better interpret the elevation of cardiac enzymes after coronary artery bypass grafting. We sought to determine if a single postoperative value of creatine kinase-myocardial band could be used as a risk factor to help predict mortality after coronary artery bypass surgery. METHODS: A retrospective analysis of prospectively collected data on 1161 patients undergoing first-time, isolated coronary artery bypass surgery utilizing normothermic cardiopulmonary bypass was conducted. Creatine kinase-myocardial band was measured the morning after surgery. Binary logistic regression, Cox proportional hazard models, and overlapping quintiles were used to illuminate the association between creatine kinase-myocardial band elevation and mortality after coronary artery bypass surgery. RESULTS: We found a threshold value of creatine kinase-myocardial band, 40 ng/mL, above which elevations were associated with increased death rates. This association held after adjustment for other factors known to contribute to postoperative mortality. However, after 1 year, there was no longer a statistically significant higher mortality associated with elevated creatinine kinase-myocardial band > 40 ng/mL. CONCLUSION: Elevation of creatine kinase-myocardial band the morning after surgery above a threshold 40 ng/mL is associated with an increased risk of mortality.