The Predictive Role of Small Airway Dysfunction in Postoperative Atrial Fibrillation After Isolated Coronary Artery Bypass Surgery

OBJECTIVE
Atrial fibrillation is the most common arrhythmia following coronary artery bypass graft surgery. The relationship between impaired lung function and atrial fibrillation has been described previously. We aimed to evaluate the prognostic influence of small airway function on predicting postoperative atrial fibrillation undergoing isolated coronary artery bypass graft surgery (CABG).


METHODS
We retrospectively analyzed 283 patients who underwent isolated CABG at our institution between January 2020 and August 2020. The patients were divided into 2 groups according to the development of postoperative atrial fibrillation. Demographic characteristics of the patients were recorded; spirometry was performed for each patient before surgery. Small airway function was determined by forced mid-expiratory flow (forced expiratory flow 25%-75%) values measured by spirometry. Propensity score matching was applied to ensure a balanced distribution of demographic data between the 2 groups.


RESULTS
The frequency of postoperative atrial fibrillation was 30.7% in our patient population. After propensity matching, forced expiratory volume in 1 second/forced vital capacity %
[80.6 (73.8-87.8) vs. 76.3 (66.7-81.6), P = 0.006] and forced expiratory flow 25%-75% (87.4 ± 14.2 vs. 75.2 ± 15.8, P = 0.001) were significantly lower in postoperative atrial fibrillation group. In multivariate analysis, white blood cell count, left ventricular ejection fraction, cross-clamp time, and forced expiratory flow 25%-75% were found to be independent predictors of postoperative atrial fibrillation development after isolated CABG. In the receiver operating characteristic curve analysis, forced expiratory flow 25%-75% with an optimal threshold value of 81% could detect the presence of postoperative atrial fibrillation with 63.8% sensitivity and 70.1% specificity.


CONCLUSION
Our study demonstrated that small airway obstruction, as indicated by forced expiratory flow 25%-75% in spirometry, can be a simple predictive tool for the development of postoperative atrial fibrillation in patients undergoing isolated CABG.