Predictive value of preoperative reduction indices with the AF at 7 days postop (chart 3.9): cut off point of 15ms with rMSSD, area under the curve was 0.71 (AUC = 0). .71; 95% CI: 0.58 - 0.84) sensitivity 43.8% specificity 90.1%, cut off point 0.75% with pNN50, area under the curve 0.68 sensitivity was 43.8% specificity was 82.2% (AUC = 0.68; 95% CI: 0.56 - 0.81), cut off point is 50ms with SDNN area under the curve of 0.66 sensitivity is 25% specificity 95% (AUC = 0.66; 95% CI: 0.49 - 0.82), cut off point is 40ms with SDANN area under the curve of 0.66, sensitivity is 18.8% specificity 98% efficiency (AUC = 0.66; 95% CI: 0.51 - 0.82).