Isoflurane may not influence postoperative cardiac troponin I release and clinical outcome in adult cardiac surgery

Background and objective: Isoflurane has been shown experimentally to protect the myocardium against infarction but the clinical relevance of these findings is not yet well established. We therefore evaluated the effects of isoflurane administration before cardiopulmonary bypass (CPB) on postoperative cardiac troponin 1 (cTnI) release and clinical outcome in a large group of adult patients scheduled for cardiac surgery. Methods: Three hundred and fifty-nine consecutive patients were included prospectively in an open observational study and divided into two groups according to whether or not isoflurane was administered before CPB. Postoperative cTnI release, in-hospital mortality, time to discharge from hospital, time to extubation and nonfatal postoperative cardiac events (number of internal cardioversions, need for inotropic support, ischaemic events, dysrhythmias and/or conduction abnormalities) were recorded. Results: Two hundred and twenty-one (62%) patients did not receive isoflurane and 138 (38176) received isoflurane (1-3% [1-0-1.8%] minimum alveolar concentration over 22 [15-33] min). Postoperative cTnI release was not significantly different between the control and isoflurane groups (5-9 [1.0-336.8] vs. 6.0 [1.5-392.0] ng mL(-1), P = 0.88). No significant differences were found in non-fatal cardiac events (63% vs. 57%, P = 0.22) and in-hospital mortality (1.8% vs. 1.4%, P = 0.79) between the control and isoflurane groups. Conclusions: No significant effect was observed on postoperative cTnI release and in-hospital outcome when isoflurane was added to standardized intravenous anaesthesia before CPB in adult patients undergoing cardiac surgery.