title: Circadian rhythm has no effect on mortality in coronary artery bypass surgery.
abstract: BACKGROUND
  The circadian variation that affects atherosclerosis has not been studied in the surgical patient. The circadian variation in mortality dependent on the time of surgery was examined in patients undergoing coronary artery bypass graft (CABG) surgery.
  
  
  METHODS
  A 4-year retrospective review of all CABG patients (n = 3140) from 1999 to 2002 was undertaken. The patients were divided into elective, urgent, and emergency cases. The cases were subdivided according to the start time of the operation as morning (7 AM to 2 PM = AM), afternoon (2 PM to 8 PM = AF), and night (8 PM to 7 AM = NT). The outcome was mortality within 30 days and compared for three different time frames: (1) AM versus AF (2) AM versus NT (3) AF versus NT for each prioritized group. Risk factors and number of anastamoses were compared for each group. Sigma Statistical package and Z-test for two group comparison were used for analysis. t-Test was used to compare age and ejection fraction.
  
  
  RESULTS
  No statistically significant difference in mortality was observed for the elective and urgent groups for each of the time periods compared. The emergency cases had significantly increased deaths in the AM and NT compared to the AF (p < 0.01 and p < 0.05, respectively). There was no statistically significant difference with respect to age, gender, number of anastamoses performed, ejection fraction, and preoperative risk factors between groups.
  
  
  CONCLUSIONS
  The mortality for nonemergent CABG is independent of the timing of surgery. Circadian variation does not influence the outcome in cardiac surgical patients.
authors.affiliation: Maimonides Medical Center, Brooklyn, New York, New York 11219, USA.
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Dhadwal
authors.forename: Mikhail
authors.initials: M
authors.lastname: Vaynblat
authors.forename: Shyama
authors.initials: S
authors.lastname: Balasubramanya
authors.forename: Murali
authors.initials: M
authors.lastname: Pagala
authors.forename: Nancy
authors.initials: N
authors.lastname: Schulhoff
authors.forename: Joshua H
authors.initials: JH
authors.lastname: Burack
authors.forename: Joseph N
authors.initials: JN
authors.lastname: Cunningham
mesh_terms: D000368:Aged; D002940:Circadian Rhythm; D001026:Coronary Artery Bypass / Q000401:mortality* / Q000706:statistics & numerical data*; D003324:Coronary Artery Disease / Q000473:pathology / Q000601:surgery*; D017558:Elective Surgical Procedures; D004630:Emergencies; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D009519:New York City / Q000453:epidemiology; D011183:Postoperative Complications; D012189:Retrospective Studies; D014850:Waiting Lists