Perioperative serum aspartate aminotransferase level as a predictor of survival after coronary artery bypass grafting

Abstract

Background: Elevated cardiac enzymes after coronary artery bypass grafting (CABG) surgery have been identified as a risk factor for worse postoperative outcome. Cardiac enzymes play an important role in the diagnosis of perioperative myocardial infarction. This study aims to investigate the predictive value of aspartate aminotransferase (AST) with respect to early and late mortality after CABG.

Methods: Patients undergoing isolated CABG in a single center between January 1998 and December 2010 were prospectively enrolled in our database. Patients were arbitrarily divided into 4 groups according to the postoperative AST level: group 1 (AST < 50 U/L), group 2 (AST = 51 to 100 U/L), group 3 (AST = 101 to 200 U/L), group 4 (AST = 201 to 300 U/L), and group 5 (AST > 300 U/L). The impact of biomedical variables on early mortality was determined using univariate and multivariate logistic regression analyses. Risk factors for late mortality were identified using Cox proportional hazard regression analyses.

Results: The study population consisted of 13,505 patients who underwent isolated CABG. Postoperative AST level was identified as a risk factor for early (odds ratio = 3.6 [2.5 to 5.4], p < 0.0001) and late mortality (hazard ratio = 1.4 [1.2 to 1.7], p < 0.001). After correction for other risk factors, AST level was an independent predictor of worse survival.

Conclusions: Elevated postoperative AST level is an independent predictor of early and late mortality after CABG. Although it is not a specific indicator for cardiac damage, it can reflect ischemic effects on the other organs as an indirect sign of depressed cardiac function.