Standardized Minnesota coding of electrocardiographic findings for purposes of cooperative research on ischaemic heart disease.

For purposes of cooperative research on multifactorial prevention of ischaemic heart disease, a standardization system was elaborated in the USSR for classification of ECG findings according to the Minnesota code. The system includes instruction about the coding rules, experimental coding, analysis of faulty codings, and finally a control test consisting in encoding several series of 200 ECG findings each. For assessing the encoder's qualification the criterion was accepted of less than 20% cases of discordance with the standard code of "ischaemic" ECG changes. It was found that after the initial instructive course it was necessary to gain experience with encoding at least 1 000 ECG to qualify the candidate for the specified expert level. The necessity is emphasized of continual surveillance of the quality of ECG classification by the encoders in different centres, and the possibility of reaching a satisfactory level of unification is declared.