Ischemia in the territory of the first major septal perforator branch anomalously originating from the first diagonal branch leads to a transient leftward shift of the QRS axis in the frontal plane: a case report.

A patient with non-Q wave myocardial infarction had severe luminal narrowing in the first major septal perforator branch, which arose anomalously from the first diagonal branch. In this case, an exercise ECG showed a transient leftward QRS axis shift.