Daytime variation does not impact outcome of cardiac surgery: Results from a diverse, multi-institutional cardiac surgery network

Abstract

Objective: Recent single-center and experimental data suggested greater adverse cardiac events for patients undergoing aortic valve replacement (AVR) in the morning (AM) versus the afternoon (PM). However, previous studies in patients undergoing coronary artery bypass grafting (CABG) have found no similar time-related difference. We examined the impact of AM versus PM operative time on surgical outcomes of CABG and AVR in a diverse, multi-institutional cardiac surgery network between January 2008 and September 2018.

Methods: The AM group included patients whose surgery start time was between 6:30 and 9 AM, whereas noon to 2:30 PM was considered PM (8901 AM/1962 PM) for CABG and (2598 AM/617 PM) for AVR. Because of imbalances in sample size, risk factors, and Society of Thoracic Surgeons predicted risk between groups, propensity score matching using all baseline characteristics was used to create 2 well-matched patient groups whose outcomes were compared.

Results: After propensity score matching, there was no difference in mortality, stroke, prolonged ventilation, renal failure, deep sternal wound infection, reoperation, myocardial injury, atrial fibrillation, or readmission between AM and PM groups for both isolated CABG and AVR. However, there were mixed differences noted in intensive care unit length of stay, postoperative length of stay, blood product use, and crossclamp time. Findings were stable when accounting for site and physician effects, whereas subgroup analyses showed similar findings in the elective, diabetic, Hispanic, and off-pump patient populations.

Conclusions: There were no differences in operative mortality nor in major morbidity between well-matched AM and PM patients undergoing either CABG or AVR.

Keywords: AVR; CABG; Society of Thoracic Surgeons; circadian; outcomes; propensity score matching.