The aortic knob index as a novel predictor of new-onset atrial fibrillation after off-pump coronary artery bypass grafting

Abstract

Purpose: To validate the predictive value of the aortic knob index for identifying new-onset postoperative atrial fibrillation (POAF) after off-pump coronary artery bypass grafting (OPCAB).

Methods: Among 156 patients who underwent isolated OPCAB, 138 consecutive patients without a history of atrial fibrillation were enrolled in this retrospective observational cohort study. The patients were divided into two groups based on the development of POAF. We compared the baseline clinical characteristics; preoperative radiographic characteristics of the aorta, including aortic knob measurements; and perioperative data, between the groups. Logistic regression analysis was performed to identify the predictors of new-onset POAF.

Results: New-onset POAF developed in 35 (25.4%) patients. Multivariate logistic regression analysis revealed that the aortic knob index was an independent predictor of POAF and yielded that the risk of POAF increased by 1.85 times when the aortic knob index increased by 0.1 (odds ratio, 1.853; confidence interval, 1.326-2.588; P < 0.001). Receiver operating characteristic analysis revealed that an aortic knob index of 1.364 constituted a cutoff value for new-onset POAF with 80.0% sensitivity and 65.0% specificity.

Conclusions: The aortic knob index on preoperative chest radiography was a significant and independent predictor of new-onset POAF following OPCAB.

Keywords: Aortic knob; Aortic knob index; Atrial fibrillation; Chest radiography; Coronary artery bypass grafting.