Association of Post-Operative Cardiac Enzyme Levels with Early Mortality Following Coronary Artery Bypass Grafting

Abstract

Background: Post-operative myocardial injury is an important determinant for mortality and morbidity following Coronary Artery Bypass Graft surgery. This study evaluated the role of serial post-operative cardiac biomarker and enzyme (CK-MB, Troponin I) measurement in predicting in-hospital mortality following CABG surgery.
Methods: This retrospective study included patients undergoing CABG procedure at Manmohan Cardiothoracic Centre from January 2020 to January 2021. Cardiac Biomarkers (CK-MB and Troponin I) were measured at 6,12 and 24 hours post-operatively. The Mann–Whitney U test was used for comparison of biomarkers between survivors (n=40) and non-survivors (n=3). Receiver Operating Characteristic (ROC) curve analysis with Youden Index was used to determine optimal cutoffs values.
Results: A total of 43 patients were enrolled in the study. In-hospital mortality was 7% (3/43) with 40 survivors and 3 non-survivors. No significant differences were observed in cardiac enzymes measured at 6 hours, between the survivors and non-survivors (Troponin I, p=0.206; CK-MB, p=0.391). However, biomarkers were significantly higher in non-survivors at 12 hours (Troponin I p=0.038; CK-MB p=0.004) and 24 hours (Troponin I p=0.007; CK-MB p=0.005). ROC demonstrated excellent predictive performance of CK-MB at 12 hours (AUC=1.00, cutoff at 146 IU/L, sensitivity 100%, specificity 100%), CK-MB at 24 hours (AUC =0.95, cutoff at 155 IU/L) and Troponin I at 24 hours (AUC=0.92, cutoff at 5.17ng/ml). However, these findings should be interpreted cautiously due to only three mortality events.
Conclusions: Post operative Cardiac biomarkers (Troponin I >5.17 ng/ml at 24 hours and CK-MB >146 IU/L at 12 hours and >155 IU/L at 24 hours) were associated with in-hospital mortality following CABG and warrants further evaluation as a post-operative risk stratification marker.
Keywords: Cardiac biomarkers; coronary artery bypass surgery; creatine kinase MB; myocardial injury; troponin I.