Sevoflurane at 1 MAC provides optimal myocardial protection during off-pump CABG

OBJECTIVE: We investigated the myocardial protective effect of sevoflurane in patients receiving off-pump coronary artery bypass grafting (OPCABG) and the role of brain natriuretic peptide (BNP). DESIGN: Forty-eight patients receiving elective OPCABG were randomly assigned to a control group, and to 0.75 MAC, 1.0 MAC and 1.5 MAC sevoflurane groups. Blood samples were collected and levels of BNP and cardiac troponin I (cTnI) were measured before anesthesia, and immediately, 24, 48 and 72 h after surgery. RESULTS: Dopamine was necessary to maintain blood pressure in the sevoflurane groups, but not in the control group (p < 0.002). 1.0 MAC sevoflurane significantly decreased post-surgical cTnI levels (p < 0.001). 0.75 MAC had no significant effect, and increasing sevoflurane concentrations to 1.5 MAC caused no further decrease in cTnI concentrations. There was no significant difference in BNP level among the groups (p = 0.227) or between any two groups, although values of BNP showed a significant correlation with cTnI values in control subjects immediately after (r = 0.847) and 24 h after (r = 0.661) surgery. CONCLUSIONS: Our results demonstrated that 1.0 MAC and 1.5 MAC sevoflurane can exert a significant myocardial protective effect. BNP cannot be used to predict the myocardial protective effect of sevoflurane in OPCABG.