Left atrial expansion index for predicting atrial fibrillation and in-hospital mortality after coronary artery bypass graft surgery

Background: Atrial fibrillation (AF), a common complication after coronary artery bypass graft surgery (CABG), is associated with prolonged hospital stay. This prospective study assessed the accuracy of left atrial parameters and additional preoperative characteristics for predicting post-CABG AF and in-hospital mortality. Methods: A total of 197 patients without hemodynamic-significant valvular problems, who received isolated CABG, were enrolled. Echocardiography was performed before CABG. Results: Compared with patients without post-CABG AF, those with post-CABG AF were older (71 vs 64 years, p < 0.0001), had a higher incidence of CABG during index hospitalization of acute myocardial infarction and preoperative respiratory failure requiring ventilator support, lower left ventricular ejection fraction (0.41 vs 0.48, p < 0.0001), lower left atrial expansion index (52.2% vs 93.3%, p < 0.0001), and higher left ventricular filling pressure (24.2 vs 19.1 mm Hg, p < 0.0001). Multivariate analysis of preoperative variables showed that independent predictors of AF included age (odds ratio [OR], 1.064; 95% confidence interval [CI], 1.022 to 1.107 per 1-year increase; p 0.002), maximal indexed left atrial volume (OR, 1.026; 95% CI, 1.002 to 1.051 per 1 mL/m ² increase; p 0.037) and left atrial expansion index (OR, 0.981; 95% CI, 0.962 to 0.998 per 1% increase; p 0.029). The left atrial expansion index was also significantly associated with in-hospital mortality (OR, 0.982; 95% CI, 0.951 to 0.996 per 1% increase; p 0.042). Incidence of post-CABG AF in patients with left atrial expansion index less than 120% progressively increased as left atrial expansion index decreased. Conclusions: Left atrial expansion index independently predicts post-CABG AF and in-hospital mortality.