Statistical analysis Data will presented as mean ± standard deviation (SD) when normally distributed or median and interquartile range (IQR) for non-normal data. Categorical variables will be compared by chi-square. Continuous variables with normal distribution will be compared using analysis of covariance (ANCOVA) adjusted for age, gender, size of MI estimated by peak CK-MB and estimated by heart rate variability sympathetic activity. Prerequisites for the ANCOVA models (linearity, normality and equal variance) will be checked using histograms, normal probability plots and residual dispersion. Non-normal continuous variables may be transformed logarithmically. If, after the transformation, they persist not normal, will be analyzed by the Kruskal-Wallis test. Analysis will be performed using the SPSS 22 application, Mac version.