title: White blood cell count and new-onset atrial fibrillation after cardiac surgery.
abstract: BACKGROUND
  Postoperative new-onset atrial fibrillation (PNAF) is the most common complication following cardiac surgery. The inflammatory response, as a potential underlying mechanism, has been extensively studied. In small studies, the white blood cell count (WBC) has been shown to be the only consistent inflammatory marker associated with PNAF. This study aimed to determine the association between perioperative WBC response and PNAF in a larger study cohort.
  
  
  METHODS
  Patients ≥18years, undergoing elective cardiac surgery with a preoperative sinus rhythm were included. WBC was routinely measured preoperatively, and daily during the first four postoperative days. Main outcomes were the difference between peak postoperative WBC and neutrophil/lymphocyte ratio (N/L ratio) and preoperative WBC and N/L ratio (ΔWBC and ΔN/L ratio respectively). Development of PNAF was evaluated in all patients with continuous 12-lead ECG monitoring.
  
  
  RESULTS
  657 patients were included and 277 (42%) developed PNAF. Univariable analyses showed a statistically significant relationship between ΔWBC (P=0.030) and ΔN/L ratio (P=0.002), and PNAF. In multivariable analysis no significant relationship was found between ΔWBC (OR: 1.14 per 1×109/L increase; 95% CI: 0.65-2.03; P=0.645), ΔN/L ratio (OR: 1.65 per 1×109/L increase; 95% CI: 0.94-2.90; P=0.089), and PNAF. Increasing age (OR: 1.08 per year; 95% CI: 1.01-1.16; P=0.022) and (additional) valve surgery (versus CABG) (OR: 4.96; 95% CI: 2.07-6.91; P≤0.001) were associated with PNAF.
  
  
  CONCLUSIONS
  The perioperative WBC response and its components were not associated with the development of PNAF.
authors.affiliation: Department of Cardio-thoracic Surgery, University Medical Centre, Utrecht, The Netherlands; Department of Anesthesiology and Intensive Care Medicine, University Medical Centre, Utrecht, The Netherlands. Electronic address: k.a.jacob@umcutrecht.nl.
authors.forename: Kirolos A
authors.initials: KA
authors.lastname: Jacob
authors.affiliation: Department of Cardio-thoracic Surgery, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Marc P
authors.initials: MP
authors.lastname: Buijsrogge
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Jos F
authors.initials: JF
authors.lastname: Frencken
authors.affiliation: Department of Clinical Chemistry and Hematology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Ten Berg
authors.affiliation: Department of Cardio-thoracic Surgery, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Willem J L
authors.initials: WJ
authors.lastname: Suyker
authors.affiliation: Department of Cardio-thoracic Surgery, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Diederik
authors.initials: D
authors.lastname: van Dijk
authors.affiliation: Department of Cardio-thoracic Surgery, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Dieleman
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001281:Atrial Fibrillation / Q000097:blood / Q000209:etiology* / Q000401:mortality; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000009:adverse effects* / Q000379:methods; D015331:Cohort Studies; D016208:Databases, Factual; D017558:Elective Surgical Procedures / Q000009:adverse effects* / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D017052:Hospital Mortality; D006801:Humans; D007958:Leukocyte Count / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009426:Netherlands; D019990:Perioperative Care / Q000379:methods; D011183:Postoperative Complications / Q000097:blood / Q000401:mortality / Q000503:physiopathology; D011446:Prospective Studies; D018570:Risk Assessment; D016019:Survival Analysis
chemical_list: D015415:Biomarkers
keywords: Atrial fibrillation; Cardiac surgery; Inflammatory cells; Inflammatory response; Perioperative care