IJCS | Volume 32, Nº6, November / December 2019

590 Table 4 - Sensitivity, specificity and positive and negative predictive values of CHADS 2 and CHA 2 DS 2 VASc scores, alone or in association with LA size, to determine atrial fibrillation following coronary artery bypass grafting and/or valvular surgery CHADS 2 > 0.5 CHA 2 DS 2 VASc < 3.5 CHADS 2 > 0.5 and LA > 39.5 mm CHA 2 DS 2 VASc < 3.5 and LA > 50.5 mm Sensitivity 91.7 52.8 68.1 65.3 Specificity 25.0 68.1 59.7 61.1 Predictive value positive 55.0 62.3 62.8 62.7 Predicitive value negative 75.0 59.0 65.1 63.8 LA: left atrial size. Table 5 - Logistic regression model of the CHADS 2 score alone (Model 1) and in association with left atrial size (Model 2) for predicting the onset of postoperative atrial fibrillation following coronary artery bypass grafting and/or valvular surgery Odds ratio (CI 95%) p-valor AUC (CI 95%) Model 1 CHADS 2 1.198 (0.859-1.156) 0.291 0.611 (0.518-0.714) Model 2 CHADS 2 1.163 (0.829-1.648) 0.387 0.643 (0.552-0.733) LA size 1.049 (0.995-1.107) 0.078 AUC: area under the curve; CI: confidence interval. Table 6 - Logistic regression model of the CHA 2 DS 2 VASc score alone (Model 3) and in association with left atrial size (Model 4) for predicting the onset of postoperative atrial fibrillation following coronary artery bypass grafting and/or valvular surgery Odds ratio (IC 95%) p-valor AUC (CI 95%) Model 3 CHA 2 DS 2 VASc 1.047 (0.784-1.401) 0.754 0.590 (0.497-0.683) Model 4 CHA 2 DS 2 VASc 1.065 (0.795-1.433) 0.673 0.633 (0.542-0.724) LA size 1.052 (0.999-1.110) 0.061 AUC: area under the curve; CI: confidence interval. Silva & Butcher Scores for prediction of AF after cardiac surgery Int J Cardiovasc Sci. 2019;32(6):585-593 Original Article in patients undergoing myocardial revascularization surgery and/or valvular surgery. As far as we know, no other study had added the contribution of left atrial size to the prediction capacity of those scores. Having tools that allows us to predict the risk of POAF in an easy and reliable way is important because it could help identify patients at risk, who would benefit from more careful monitoring in the postoperative period, as well as, for the institution of prevention measures. Patients with POAF were older compared to those who did not develop arrhythmia. Advanced age is, admittedly, a major risk factor for AF in patients in general 16,17 and in those undergoing cardiac surgery. 18,19 In fact, population aging, especially in emerging countries,