[R-wave augmentation in acute myocardial infarction (author's transl)].

In 18 out of 419 successive myocardial infarctions an increase in R-wave amplitude compared to the pre-infarction ecg had been observed. It concerned to leads III, aVF and II in posterior and inferior infarctions. The alteration of R-wave amplitude was accompanied by a dextroversion of electrical heart axis in the frontal plane. Direction of inscription of QRS loop changed in most cases. R-wave increase was demonstrated in the first ecg after the beginning of subjective symptoms and disappeared within few hours or days in general. Clinical course was rather serious in the cases described. As a pathophysiological mechanism of the phenomenon mentioned above either the influence of an injury potential upon ecg pattern or the presence of left posterior conduction defect is discussed.