Daytime Variation of Clinical Outcome in Cardiac Surgery: A Propensity-Matched Cohort Study

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.

Retrospective cohort study.

A single academic center.

All patients undergoing nonemergent aortic valve replacement (AVR) ± coronary artery bypass graft 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 multivariate logistic regression with a 1:1 matching ratio was performed to ensure that the two groups were comparable. This allowed obtaining 269 pairs, for a total of 538 patients.

The objective of the study was to assess whether there were differences in perioperative and postoperative outcomes between the morning and the afternoon groups.

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 were no between-group differences for both postoperative evolution of troponin T plasma levels and the maximum postoperative troponin T plasma level.

These results did not support the hypothesis that the timing of the surgery could influence the tolerance to ischemia and reperfusion injury, at least in patients undergoing nonemergent AVR or a combined AVR with coronary artery bypass graft.