Mixed venous oxygen saturation predicts short- and long-term outcome after coronary artery bypass grafting surgery: a retrospective cohort analysis

Abstract

Background: Complications of an inadequate haemodynamic state are a leading cause of morbidity and mortality after cardiac surgery. Unfortunately, commonly used methods to assess haemodynamic status are not well documented with respect to outcome. The aim of this study was to investigate Sv(O2) as a prognostic marker for short- and long-term outcome in a large unselected coronary artery bypass grafting (CABG) cohort and in subgroups with or without treatment for intraoperative heart failure.

Methods: Two thousand seven hundred and fifty-five consecutive CABG patients and subgroups comprising 344 patients with and 2411 patients without intraoperative heart failure, respectively, were investigated. Sv(O2) was routinely measured on admission to the intensive care unit (ICU). The mean (sd) follow-up was 10.2 (1.5) yr.

Results: The best cut-off for 30 day mortality related to heart failure based on receiver-operating characteristic analysis was Sv(O2) 60.1%. Patients with Sv(O2) <60% had higher 30 day mortality (5.4% vs 1.0%; P<0.0001) and lower 5 yr survival (81.4% vs 90.5%; P<0.0001). The incidences of perioperative myocardial infarction, renal failure, and stroke were also significantly higher, leading to a longer ICU stay. Similar prognostic information was obtained in the subgroups that were admitted to ICU with or without treatment for intraoperative heart failure. In patients admitted to ICU without treatment for intraoperative heart failure and Sv(O2) ≥60%, 30 day mortality was 0.5% and 5 yr survival 92.1%.

Conclusions: Sv(O2) <60% on admission to ICU was related to worse short- and long-term outcome after CABG, regardless of whether the patients were admitted to ICU with or without treatment for intraoperative heart failure.