What is the exact predictive role of preoperative white blood cell count for new-onset atrial fibrillation following open heart surgery?

BACKGROUND: Atrial fibrillation (AF) occurs in 30% patients on the second or third day post operation; therefore, it is the most prevalent and complicated arrhythmia after open heart surgery. White blood cell (WBC) count seems to be most significantly associated with cardiovascular disorders. This study was designed to evaluate the exact relationship between preoperative WBC count and post-Coronary artery bypass graft (CABG) AF in patients with severe left ventricle (LV) dysfunction who underwent elective off-pump coronary artery bypass.

METHODS: This study was conducted on 104 patients from among 400 patients with severe LV dysfunction undergoing elective off-pump CABG surgery from February 2011 to February 2012, in Afshar Cardiovascular Center, Yazd, Iran. Patients with emergency surgery, unstable angina creatinine higher than 2.0 mg/dL, malignancy, or immunosuppressive disease were excluded. Preoperative serological tests of the participants, such as WBC counts, were saved in their medical dossiers. Of the 400 patients undergoing CABG, AF was found in 54 cases; these 54 male patients formed the experimental group and 60 other patients in the intensive care unit (ICU) and hospital stay without postoperative AF were part of the control group.

RESULTS: The average age of the patients was 68.5±12.8 years. WBC counts in patients with and without AF three days before surgery were 12,340±155 and 8,950±170, respectively. On surgical day, WBC counts in the patients with and without AF were 13,188±140 and 9,145±255, respectively (P value three days before surgery: 0.04; P value on surgical day: 0.01). Of the 54 male patients with postoperative AF (POAF), duration of AF was more in cases with elevated WBC count (12,000-14,000) than in those with lower elevated WBC count (10,000-12,000) (]P=0.025), but there was no relationship between frequency of recurrence of AF and grading of elevation of WBC count (]P=0.81).

CONCLUSION: These findings show that three days before surgery and on surgery day, there was a difference in WBC count between both groups. So, preoperative WBC count may predict the incidence and duration of AF; however, it cannot be a predictor of the frequency of recurrence of AF. Finally, WBC count is an independent marker for POAF and duration of AF.