Comparison between normothermic and mild hypothermic cardiopulmonary bypass in myocardial revascularization of patients with left ventricular dysfunction

Abstract

Aims: The aim of this study was to investigate whether normothermic bypass is superior to mild hypothermia in patients with poor left ventricular function. This was achieved by studying defibrillation rates, postoperative requirements of cardiac pacing or other morbidity issues and mortality in patients with left ventricular dysfunction operated upon for elective coronary revascularization. Methods: Data were collected retrospectively from 252 consecutive patients with left ventricular dysfunction (ejection fraction ≤35%) undergoing coronary revascularization between January 2005 and January 2011. Patients operated upon under mild hypothermia (32ºC) were placed in Group 1 and under normothermia (≥35ºC) were placed in Group 2. Comorbidities and postoperative complications were recorded. Results: There were 128 patients in Group 1 and 124 patients in Group 2. Plasma concentrations of CK-MB and troponin T peaked at 6 hours postoperatively, with no significant difference between the groups. Despite longer aortic cross-clamp time and total bypass time in Group 2, significantly less defibrillation requirement rates after aortic declamping was observed. Hospital mortality occured in 16 patients; 8 patients in each group. Conclusions: Normothermia enables less requirement for defibrillation after aortic declamping and postoperative cardiac pacing in patients with left ventricular dysfunction, which may be interpreted as better myocardial protection under normothermic bypass. However, maintaining normothermia had no effect on postoperative stroke, postoperative atrial fibrillation, renal failure development and mortality.