Related Experiment Video
Updated: Jan 8, 2026

Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments
Published on: August 8, 2019
The Effects of Daytime Variation on Short-Term Outcomes of Cardiac Surgical Patients: A PRISMA-Compliant Systemic
Yun-Tai Yao1, Shuo Huang2, Mark Chao3
1Department of Anesthesiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Peking; Union Medical College and Chinese Academy of Medical Sciences, Beijing, China; Evidence in Cardiovascular Anesthesia (EICA) Group, Beijing, China; Center of Outcomes Research, Department of Anesthesiology, Critical Care and Pain Medicine, University of Texas, Houston, TX; Outcomes Research Consortium, Houston, TX.
Objective:
Circadian rhythms influence cardiovascular physiology and surgical stress responses, raising the possibility that the timing of cardiac surgery may affect outcomes. Previous studies have reported conflicting results regarding whether morning (AM) versus afternoon (AF) surgery influences perioperative morbidity and mortality. The present study aimed to systematically evaluate whether the timing of cardiac surgery, specifically AM versus AF procedures, influences short-term outcomes.
Design:
A meta-analysis of observational cohort studies.
Settings:
Cardiovascular centers.
Participants:
Patients who underwent elective cardiac surgery.
Interventions:
The AM or the AF group.
Measurements:
The primary outcome was hospitalized mortality. Secondary outcomes included major morbidities (new-onset atrial fibrillation, myocardial infarction, stroke, renal and infectious complications, reexploration, mechanical circulatory support) and postoperative recovery profiles (mechanical ventilation duration, length of stay [LOS] in the intensive care unit and hospital).
Main Results:
Fourteen observational studies involving 135,672 patients (81,391 in the AM group and 54,281 in the AF group) were included. Pooled analysis showed no significant difference in hospitalized mortality between the two groups (1.25% [998/79,550] v 1.17% [615/52,442], OR = 1.09, 95% CI = 0.99 to 1.21; p = 0.08]. The incidences of myocardial infarction, stroke, renal and infectious complications, reexploration, and mechanical circulatory support use were also comparable. However, AM surgery was associated with a modestly higher incidence of new-onset atrial fibrillation (26.05% [2,319/8,907] v 25.50% [1,000/3,921], OR = 1.11, 95% CI = 1.01 to 1.21; p = 0.03). No significant differences were observed in mechanical ventilation duration [MD = -0.20 hours, 95% CI = -0.40 to 0.00; p = 0.05], intensive care unit LOS [MD = -0.35 hours, 95% CI = -6.14 to 5.43; p = 0.90], or hospital LOS [MD = -0.10 days, 95% CI = -0.39 to 0.19; p = 0.49].
Conclusions:
These findings suggest that circadian influences on elective cardiac surgical outcomes are limited. Future multicenter prospective studies are warranted to further define the role of surgery timing in high-risk populations.
More Related Videos
05:41Left Anterior Descending Coronary Artery Ligation for Ischemia-Reperfusion Research: Model Improvement via Technical Modifications and Quality Control
Published on: December 16, 2022
03:13Technical Refinement of a Bilateral Renal Ischemia-Reperfusion Mouse Model for Acute Kidney Injury Research
Published on: November 3, 2023
Related Concept Videos
Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
Cardiomyopathy VII: Pre and Post Operative Nursing Management