Body surface isopotential maps in old inferior myocardial infarction undetectable by 12 lead electrocardiogram

The purpose of this study is to examine the value of body surface isopotential maps in the diagnosis of old inferior myocardial infarction that can not be diagnosed by 12 lead ECG. Forty-three patients with a Q wave of at least 0.02 sec but less than 0.04 sec in width and also less than 25% of the R wave in depth in lead aVF of the 12 lead ECG were seleted for this study. The patients were divided into infarction and noninfarction groups based on their clinical histories and cardiac catheterization data. The infarction group showed characteristic surface maps with a minimum which moved from the left posterior chest to the lower back or from the lower back to the right anterior lower chest in the early phase of QRS. The noninfarction group exhibited a minimum which shifted from the back to the right upper chest or from the left anterior chest to the lower back in the same phase. Thus, both groups were clearly distinguishable from each other by the positional change of the minimum in the early phase of QRS. This study suggested that body surface maps contain diagnostic information concering the presence or absence of inferior myocardial infarction which is not easily available from the 12 lead ECG.