The impact of office heart rate (HR) on ECG dispersion mapping readings was investigated in medical students. The cross-sectional study enrolled 72 students aged 21-26 years (mean age 21.9±0.1 years) from the N.N. Burdenko Voronezh State Medical Academy, among them there were 18 young men and 54 young women. By taking into account the findings, two groups of respondents were formed: 1) those with a resting office HR above 80 beats per minute; 2) those with a resting office HR below 80 beats per minute. The students were examined using a CardioVisor-6C device at resting and during exercise (20 squattings). The exercise test in the students with a resting office HR more than 80 beats per minute revealed myocardial electrical heterogeneity. Considering the fact that the respondents with a resting office HR above 80 beats per minute have no abnormalities in major integral indices, it is expedient to carry out an exercise test to detect preclinical myocardial changes.