Critical analysis of the vectorcardiogram's reliability in the quantitative diagnosis of old myocardial infarction.

The purpose of this work is to verify if the vectorcardiogram (VCG) can be used for the quantification of old myocardial infarction (OMI). 50 cases of acute myocardial infarction were studied by mean of seriate determination of MB-CK isoenzyme and Sobel Index (SI); 4 weeks later, Frank's VCG was recorded. The studied cases did not show any conduction disturbances or other electrical abnormalities besides the sign of OMI. The 50 cases were divided into two groups according to the site of the necrosis: Group A, including 27 cases of inferior and/or posterior infarction and Group B, including 23 cases of septal and/or anterior infarction. On the VCG records, the variables related to OMI and to the general shape of ventricular depolarization and repolarization were measured. The electrical variables and the SI were compared by means of the methods of linear regression and of principal components analysis. No significant correlations were detected. Therefore, we conclude that the VCG is useless in the quantitative assessment of OMI; that such terms as "extensive, localized" and so on, at present widely used in electro- and vector-cardiography, are misleading if based only on surface electrical records obtained at distance from the acute phase of infarction and should therefore be avoided; that the work is consistent with the hypothesis that the electrical pattern of OMI could depend mainly upon peripheral intraventricular conduction disturbances.