Masquerading Bundle Branch Block

Masquerading bundle branch block can be either of the standard type or the precordial type. In the standard type, precordial leads show right bundle branch block pattern and frontal plane leads show left bundle branch block pattern. Precordial type of masquerading bundle branch block is characterised by right bundle branch block pattern in anterior leads and left bundle branch block in leads V4 to V6. Several authors have reported a poor prognosis for masquerading bundle branch block.