Contribution of Frank ECG measurements to the quantitative estimation of old anterior myocardial infarction

Twenty scalar and vector measurements of the Frank ECG were compared between men categorized as having suffered nontransmural (n = 47) and transmural anterior myocardial infarction (n = 124), on the basis of clinical and angiocardiographic findings. Variables which showed significant differences of group means between cases with anterior wall hypokinesis and anterior wall akinesis and/or dyskinesis were submitted to linear discriminant-function analysis. The stepwise selection procedure of Rao's method demonstrated the three most decisive variables for differentiation to be: (1) the angular sum of dorsal displacement of the 5 initial QRS vectors obtained at 0.01 sec intervals (sum of negative azimuth angles); (2) the Q duration in lead Z (anterior force); and (3) the Q duration in lead X (rightward force). The classification routine can identify correctly 81% of the nontransmural and 79% of the transmural anterior infarctions. The high percentages of correctly classified nontransmural and transmural infarctions show significant diagnostic potential for patient management. From the results of discriminant-function analysis, it is apparent that the sum of negative azimuth angles derived from the dorsally directed vectors during the first half of QRS exceeds substantially the scalar variables in their contribution to differentiation of the two conditions.