Prognostic value of serum myoglobin in patients after cardiac surgery

Purpose. Serum myoglobin as a marker of myocardial damage and injury has been shown to be of prognostic value in patients with cardiovascular events. In this study, we analyzed the prognostic value of serum myoglobin in comparison to other parameters of muscle damage and renal function in patients after cardiac surgery. Methods. We retrospectively analyzed data from 373 cardiac surgical patients (mean age, 66 +/- 10 years; range, 30-88 years) by using the highest levels of serum myoglobin, creatinine, and creatine phosphokinase (CK) within the first 24h after admission to the Intensive Care Unit (ICU). Patients' severity of illness was assessed by the Acute Physiology and Chronic Health Evaluation (APACHE) II score. Predictive properties, in terms of ICU mortality and need for renal replacement therapy (RRT), were analyzed by receiver operating characteristics (ROC) statistics and described by the area under the curve (AUC). Results. Serum myoglobin was significantly higher in non-survivors (n = 29) than in survivors (n = 344; median, 1449 vs 356 mu g(.)l(-1); P < 0.001). With respect to ICU mortality, AUCs were 0.81 for myoglobin, 0.80 for creatinine, and 0.63 for CK. For comparison, an AUC of 0.82 was found for the APACHE II score. In terms of the need for RRT, AUCs were 0.87 for myoglobin, 0.92 for creatinine, and 0.60 for CK. For both endpoints, the AUCs of myoglobin and creatinine were significantly higher than that for CK. Conclusion. Serum myoglobin is associated with outcome in patients after cardiac surgery. Prediction of ICU mortality and need for RRT was comparable for myoglobin and creatinine, while both were significantly superior to CK.