Analysis of the Orthogonal Electrocardiogram and Vectorcardiogram in Ventricular Conduction Defects With and Without Myocardial Infarction

Correlations were computed for 320 electrocardiographic measurements and variables of ventricular conduction defects in 452 unselected patients. The variables consisted of right and left ventricular conduction defects with and without myocardial infarction. Quantitative criteria were established which led to the identification of infarction in the presence of a ventricular conduction defect. The data were analyzed by two methods: (1) using four independent measurements, and (2) discriminant function analysis in conjunction with a likelihood ratio test using 9 or 10 measurements. Both techniques yielded similar results. In the presence of left ventricular conduction defects 52% of the cases of infarction were identified with a 14% false positive diagnosis of infarction. In the cases of right ventricular conduction defects the results were 54% and 11%, respectively. In both, the sensitivity could be increased at the expense of an increase in the false positive frequency. This study confirms the difficulties in the electrocardiographic diagnosis of infarction in the presence of left ventricular conduction defects. In addition, it emphasizes that a simlar problem exists with right ventricular conduction defects, a finding which has not been adequately appreciated to date.