The frontal plane vectorcardiogram in old inferior myocardial infarction. Criteria for diagnosis and electrocardiographic correlation.

The early part of the frontal plane QRS loop (Frank lead system) was analyzed in 100 consecutive patients with an old inferior myocardial infarction. In order to be included in this study, all cases had to fulfill, at some time, Myers' classical ECG criteria for the diagnosis. The vectorcardiogram was made months to years after the patient's original acute episode. Several scalar and planar parameters, pertaining to these frontal plane early QRS vectors, were analyzed. As a result of this analysis and in order to prevent overlap with values found in 315 normal control subjects, VCG criteria, based on the interrelationships of several of these parameters, were proposed for the diagnosis of old inferior myocardial infarction. Pitfalls in the use of only scalar or planar analyses were pointed out. In 90 of the 100 cases the diagnosis was made on the basis of the proposed VCG criteria. However, the ECG made at the same time fulfilled Myers' or Goldberger's classical criteria in only 42 of the 100 cases. All cases diagnosed from the ECG were also diagnosed from the VCG.