Off-pump coronary artery bypass attenuates transient hepatocellular damage after myocardial revascularization

Objective: Cardiopulmonary bypass (CPB) affects hepatocellular integrity and occasionally results in liver dysfunction after cardiac surgery. Performing coronary artery bypass graft surgery without CPB may help to reduce the risk of this complication and better preserve perioperative liver function. This study compared perioperative hepatocellular damage in patients undergoing on-pump and off-pump bypass surgery. Design: Prospective study. Setting: University hospital. Participants: Patients scheduled for elective on-pump (n = 21) and off-pump (n = 17) coronary artery bypass surgery. Measurements and Main Results: Liver function was assessed by serum levels of alcohol dehydrogenase (AD) and α-glutathione S-transferase (α-GST), which serve as more sensitive indices of hepatocellular injury than do conventional transaminases. Arterial blood was sampled at 6 stages: after induction of anesthesia (baseline); at the end of CPB in the on-pump group or on completion of the last distal anastomosis in the off-pump group; at the end of surgery; and 6 hours, 12 hours, and 24 hours after the end of anesthesia. The off-pump patients showed significantly lower increases in serum AD and α-GST levels than did the on-pump group. AD and α-GST values increased in the on-pump patients after the initiation of CPB and peaked at the end of surgery, with a return to baseline at 12 hours and 24 hours after the end of anesthesia. No clinically relevant liver dysfunction was observed in either group. Conclusions: CPB induced transient subclinical hepatocellular damage, whereas off-pump revascularization attenuated this damage.