Myocardial Protection with Isoflurane During Off-Pump Coronary Artery Bypass Grafting: A Randomized Trial

Abstract

To analyze the hemodynamic effects and myocardial injury using troponin-T and creatine phosphokinase (CPK-MB) with isoflurane and compare it with a control group in patients undergoing off-pump coronary artery bypass (OPCAB) surgery. This prospective, randomized study was performed in patients scheduled for elective OPCAB surgery during February 2007 to February 2009. Tertiary care, university teaching hospital. Forty-five patients undergoing elective OPCAB surgery. Patients were randomly allotted to receive either isoflurane (inspired concentration between 1.0% and 2.5%) or propofol (1.5 to 3.5 mg/kg/h) during OPCAB surgery. The concentration of these agents was titrated such that the BIS value was maintained between 50 and 60. The hemodynamic data were measured and recorded after induction of anesthesia (baseline), during the distal anastomosis of each coronary artery, and 5 and 30 minutes after giving protamine. In addition, blood samples for troponin-T and CPK-MB were obtained after induction (baseline), after 6 hours and 24 hours postoperatively. The cardiac index was significantly higher in the isoflurane group at all stages, except during distal anastomosis of the diagonal branch of the left anterior descending artery (p < 0.05). There was a significant increase in troponin-T levels at 6 and 24 hours after surgery in the propofol group (from 0.037 ± 0.013 ng/mL to 0.098 ± 0.045 ng/mL and 0.081 ± 0.025 ng/mL, respectively, p < 0.05). Significant increases in the troponin-T levels were observed at 6 hours (from 0.033 ± 0.011 ng/mL to 0.052 ± 0.025 ng/mL, (p < 0.05) in the isoflurane group, and the levels in the propofol group were significantly higher than the isoflurane group at 6 and 24 hours after surgery (p < 0.05). The CPK-MB levels increased in both groups, but were not statistically different. Isoflurane provides protection against myocardial damage in a clinically used dosage as documented by lower levels of troponin-T in patients undergoing OPCAB surgery.