IJCS | Volume 32, Nº6, November / December 2019

591 Chart 2 - Predictive ability of models constituted by the scores alone or in association with left atrial size to predict new-onset atrial fibrillation after coronary artery bypass graft surgery and/or valvular surgery. Sensitivity Specificity CHADS 2 CHADS 2 + LA CHADS 2 - VASC CHADS 2 -VASC + LA Silva & Butcher Scores for prediction of AF after cardiac surgery Int J Cardiovasc Sci. 2019;32(6):585-593 Original Article will play an important role in changing the incidence of this type of arrhythmia in the general population, as well as in patients undergoing cardiac surgery. 5 The mean ejection fraction in both groups was considered within normal limits, although LA size was slightly increased in both groups. 20 When AF is addressed in the context of heart failure, arrhythmia is more frequent in patients with normal ejection fraction, due to volume overload and pressured atrial chambers. 21 Atrial remodeling, caused by a structural rearrangement of myocardial fibers, is directly linked with the presence of AF. 21 Other authors have reported that LA size is associated with the occurrence of arrhythmia 2,4,9,22 and seems to be the best discriminant between postoperative patients who developed POAF and those who did not. 14 Considering the important role played by the LA in the physiopathology of AF, and the results of previous studies, we decided to test the predictive capacity of the scores alone and combined with this measure, even though no difference was observed between the groups with and without AF in relation to the size of this heart chamber. This will be further discussed below. Regarding the use of continuous medication, comparison between the groups with and without AF showed that only the use of digitalis was different. Although this drug was prescribed with the aim of treating heart failure, its action on cell membranes and increased vagal tonus 5 could contribute to reduce the onset of POAF. It is known that the risk to develop AF in the postoperative of cardiac surgery may vary depending on the type of surgery. In a multicenter study, the risk of POAF was higher in patients who had undergone coronary artery bypass grafting combined with valvular surgery (OR: 1.8; CI 95%: 1.2 - 2.7) or valve surgery alone (OR: 1.4; CI 95%: 1.1 - 1.9) comparedwith coronary artery bypass grafting surgery alone. 23 Although studies have associated the use of ECC with increased postoperative complications, among them, the occurrence of atrial fibrillation, 24 this study did not find significant differences