Abstract 4774: Neutrophil/Lymphocyte Ratio as a Predictor of New-Onset Atrial Fibrillation Following Coronary Artery Bypass Grafting
Introduction. Atrial fibrillation (AF) is a common complication in patients undergoing coronary artery bypass grafting (CABG). Prior studies demonstrate an association between peri-operative inflammation and risk of developing post-operative AF. The neutrophil/lymphocyte (NL) ratio is emerging as a clinically useful marker of inflammation in patients with cardiovascular disease. We investigated NL ratio as a predictor of AF in patients undergoing CABG.
Methods. Two hundred and seventy five patients undergoing non-emergency CABG were recruited. Patients with prior atrial arrhythmia or who were undergoing concomitant valve surgery were excluded. NL ratio was calculated from pre-operative blood samples, and on post-operative days 1 and 2. Holter monitoring was used to diagnose post-operative AF, and the study end-point was any AF lasting longer than 30 seconds.
Results. Patients who developed AF (n=107, 39%) had a higher pre-operative NL ratio (median 3.0 vs 2.4, p=0.001), but there was no difference in other white cell parameters or high sensitivity CRP. Post-operative NL ratio was also higher in patients with AF (day 2, median 9.2 vs 7.2, p<0.001) and was more strongly associated with AF than total WCC or neutrophil count (NL ratio: OR 1.11 per unit, p=0.001). Post-operative NL ratio remained independently predictive of AF in a multivariable model with all study variables, including age, patient characteristics, medication and peri-operative variables (OR 1.13 per unit, p=0.006).
Conclusion. Elevated pre-operative NL ratio is associated with an increased risk of AF following CABG. Heightened post-operative inflammatory response, assessed by post-operative NL ratio, is independently associated with AF. These results provide further support for an inflammatory etiology in post-operative AF.