A method of processing of electrocardiogram, which comprises the following steps: - providing an electrocardiogram comprising signals in at least two channels; - selecting at least two frequency ranges of the signal in each of the said at least two channels; - calculating an envelope for the signal in each frequency range in each channel; - dividing the calculated envelope of the signal in each frequency range in each channel into QRS complex segment envelopes; - computing an average or median envelope as an average or median of QRS complex segment envelopes for each frequency range in each channel; - normalizing the average or median envelope to obtain a normalized average or median envelope for each frequency range in each channel; characterised in that the normalization is performed by dividing the average or median envelope of each frequency range in each channel by its integral or by a maximal value reached in the average or median envelope, in each frequency range and each channel separately, wherein the integral or the maximal value are calculated within an interval of a minimum of 50 ms before the position of QRS complex and minimum 50 ms after the position of QRS complex; wherein the position of the QRS complex is the temporal center of the QRS complex; - calculating a signal average or median envelope from the normalized average or median envelopes of all frequency ranges within each channel; and - calculating a first temporal duration (Vdi) of the signal average or median envelope as time length of a horizontal line crossing the signal average or median envelope, wherein the horizontal line is at a level within 10-70 percent of the maximum value of the signal average or median envelope; and/or - calculating a second temporal duration (AVdi) of the signal average or median envelope as time difference between the first and the last intersection of the signal average or median envelope with the horizontal line, wherein the horizontal line is at a level within 10-70 percent of the maximum value of the signal average or median envelope or of the final average or median envelope; - determining the local depolarization duration of heart ventricles in units of time as the first temporal duration, and/or determination the total local depolarization duration of heart ventricles in units of time as the second temporal duration. - providing an electrocardiogram comprising signals in at least two channels; - selecting at least two frequency ranges of the signal in each of the said at least two channels; - calculating an envelope for the signal in each frequency range in each channel; - dividing the calculated envelope of the signal in each frequency range in each channel into QRS complex segment envelopes; - computing an average or median envelope as an average or median of QRS complex segment envelopes for each frequency range in each channel; - normalizing the average or median envelope to obtain a normalized average or median envelope for each frequency range in each channel; characterised in that the normalization is performed by dividing the average or median envelope of each frequency range in each channel by its integral or by a maximal value reached in the average or median envelope, in each frequency range and each channel separately, wherein the integral or the maximal value are calculated within an interval of a minimum of 50 ms before the position of QRS complex and minimum 50 ms after the position of QRS complex; wherein the position of the QRS complex is the temporal center of the QRS complex; - calculating a signal average or median envelope from the normalized average or median envelopes of all frequency ranges within each channel; and - calculating a first temporal duration (Vdi) of the signal average or median envelope as time length of a horizontal line crossing the signal average or median envelope, wherein the horizontal line is at a level within 10-70 percent of the maximum value of the signal average or median envelope; and/or - calculating a second temporal duration (AVdi) of the signal average or median envelope as time difference between the first and the last intersection of the signal average or median envelope with the horizontal line, wherein the horizontal line is at a level within 10-70 percent of the maximum value of the signal average or median envelope or of the final average or median envelope; - calculating a first temporal duration (Vdi) of the signal average or median envelope as time length of a horizontal line crossing the signal average or median envelope, wherein the horizontal line is at a level within 10-70 percent of the maximum value of the signal average or median envelope; and/or - calculating a second temporal duration (AVdi) of the signal average or median envelope as time difference between the first and the last intersection of the signal average or median envelope with the horizontal line, wherein the horizontal line is at a level within 10-70 percent of the maximum value of the signal average or median envelope or of the final average or median envelope; - determining the local depolarization duration of heart ventricles in units of time as the first temporal duration, and/or determination the total local depolarization duration of heart ventricles in units of time as the second temporal duration.