A method and an arrangement for predicting perioperative myocardial ischemia. Heart rate measurements are carried out for example at night- and day-time before the operation to obtain heart rate data. The heart rate data obtained is carried to a device configured to carry out heart rate variability analysis (HRV). Dynamic heart rate variability analysis is carried out by utilizing fractal analysis of the heart rate data and fractal correlation properties obtained from the measured heart rate data are examined to find considerable lowering of the fractal correlation properties during for example night-time when compared to day-time.