Comparison between two classification systems of the electrocardiogram in epidemiologic investigations. The Minnesota code and the Washington D.C., code.

The electrocardiocardiogram (ECG) is a basic method used in cardiovascular epidemiologic investigations. Its value as a prognostic indicator of future cardiac events has been fully demonstrated, and some ECG items, such as a pattern of left ventricular hypertrophy, are considered as among the definite cardiovascular risk factors.1 However, the prevalence rates of various ECG abnormalities in a given population will depend on the true prevalence of cardiac disease as well as on the sensitivity and specificity of the ECG criteria included in the classification system. Different ECG coding systems using different criteria might provide different rates of ECG abnormalities in the same population. The most widely used and internationally accepted ECG coding system is the Minnesota code (MC), introduced by Blackburn in the 1960s. x This system, designed for the standard 12-lead ECG, was developed on an empirical basis, according to generally accepted criteria. More recently, Pipberger et al. proposed a new classification system, developed at the Washington VA hospital. 3 The Washington, D.C. code (WC) is designed for use with the Frank orthogonal lead system. By contrast with the MC, the WC has been validated on a population with wellknown cardiovascular status. The purpose of this study was to compare the two coding systems by applying them to the same population sample.