Atrial fibrillation with left bundle branch block and intermittent right axis deviation during acute myocardial infarction.

Rarely the ECG shows an LBBB with changing QRS morphology and changing axis deviation. The intermittent positive aspect of the neglected lead aVR indicates an intermittent right axis deviation in the presence of complete LBBB. An additional left posterior fascicular block accompanying predivisional LBBB is the possible explanation. We describe the case of a 78-year-old Italian woman admitted to the Cardiology Unit with acute myocardial infarction and permanent atrial fibrillation. Electrocardiographic changes were observed. The ECG showed atrial fibrillation and LBBB with intermittent left axis deviation or atrial fibrillation and LBBB with intermittent right axis deviation.