STEMI with RBBB

STEMI with new RBBB:
- RBB is supplied by first septal branches of LAD -- means proximal LAD

Right bundle branch block in anterior MI is an independent marker of poor prognosis; this is due to the extensive myocardial damage involved rather than the conduction disorder itself. 

http://lifeinthefastlane.com/ecg-library/anterior-stemi/