Daytime variation of clinical outcome in cardiac surgery: a propensity-matched cohort study

Abstract Objective The purpose of the present study was to investigate the hypothesis of a nychthemeral variation in the tolerance to ischemia and reperfusion injury in adult cardiac surgeries. Design Retrospective cohort study. Setting A single academic center. Participants All patients undergoing non emergent AVR ± CABG between January 2012 and May 2018 were included. They were divided into two groups (morning and afternoon) according to the time of the day at the beginning of surgery. Propensity score matching estimated by multivariable logistic regression with a 1:1 matching ratio was performed to ensure that the two groups were comparable. This allowed to obtain 269 pairs, for a total of 538 patients. Intervention The objective of the study was to assess whether there was a difference in perioperative and postoperative outcomes between the morning and the afternoon groups. Results There was no between-group difference in the primary composite endpoints, namely the occurrence of death, myocardial infarction, low cardiac output, and stroke during the 30 days following the surgery. Regarding cardiac biomarkers, there was no between-group difference for both postoperative evolution of troponin T plasma levels and the maximum postoperative troponin T plasma level. Conclusion These results do not support the hypothesis that the timing of the surgery could influence the tolerance to ischemia and reperfusion injury, at least in patients undergoing non emergent AVR or a combined AVR with CABG.