IJCS | Volume 32, Nº6, November / December 2019

588 Table 2 - Minimum and maximum values observed in the laboratory tests results conducted in the immediate postoperative period of patients with (n = 72) and without (n = 72) postoperative atrial fibrillation Minimum p-value* Maximum p-value* Magnesium, mEq/L, mean (SD) With AF 1.5 (0.4) 0.248 2.1 (0.5) 0.950 Without AF 1.6 (0.4) 2.1 (0.6) Potassium, mEq/L, mean (SD) With AF 3.8 (0.4) 0.251 4.4 (0.5) 0.780 Without AF 3.9 (0.9) 4.4 (0.9) Sodium, mEq/L, mean (SD) With AF 135.5 (3.2) 0.194 138.9 (3.7) 0.404 Without FA 136.6 (6.1) 139.6 (5.9) Calcium, mEq/L, mean (SD) With AF 1.15 (0.06) 0.406 1.25 (0.1) 0.984 Without AF 1.16 (0.06) 1.25 (0.1) CRP, mEq/L, mean (SD) With AF 8.4 (11.0) 0.019 111.1 (69.7) 0.099 Without AF 16.8 (27.4) 92.6 (64.1) Creatinine, mEq/L, mean (SD) With AF 1.0 (0.4) 0.277 1.4 (0.6) 0.601 Without AF 1.3 (1.6) 1.6 (1.7) Urea, mEq/L, mean (SD) With AF 38.1 (16.0) 0.840 48.0 (22.1) 0.210 Without AF 38.7 (18.5) 43.6 (19.8) SD: standard deviation; mEq/L: milliequivalents per liter; CRP: C-reactive protein; AF: atrial fibrillation; (*) Student’s t-test. Silva & Butcher Scores for prediction of AF after cardiac surgery Int J Cardiovasc Sci. 2019;32(6):585-593 Original Article the age is associated with the onset of arrhythmia in the postoperative period (p = 0.050). In relation to medication taken on a regular basis at home, the use of different classes was observed, among which, antihypertensives, antiarrhythmics, statins, antiplatelet agents, anticoagulants anddiuretics. However, we only found statistically significant difference between patients with or without POAF in relation to the use of digitalis (0%, n = 0 vs 6.9%, n = 5, respectively; p = 0.026). Laboratory tests results conducted in the preoperative periodwere not analyzed because theywere not available for many patients. Table 2 describes the minimum and maximum values observed in laboratory tests results collected in the first 24 hours after surgery. The other intra- and postoperative data of interest for this study are described in Table 3. The CHADS 2 mean scores for patients with and without POAF were, respectively, 1.82+1.05 and 1.49+1.18 (p = 0.077). The CHA 2 DS 2 VASc mean scores, on the other hand, were, 3.38 + 1.53 and 2.96 + 1.56, in this sequence (p = 0.109). In order to evaluate the predictive capacity of these scores, alone or combined with LA size, we established the cut-off point of each score to better identify the patients who developed POAF (Chart 1). Table 4 describes the predictive capacity of these scores, either alone or associated with LA size, to determine the onset of POAF.