This interesting and instructive ECG was contributed by Jason Roediger, ECG Guru Extraordinaire, and one of the experts featured on our '"Ask the Experts" page. It is an excellent example of acute inferior wall M.I. with left bundle branch block. Left bundle branch block normally displays ST elevation and depression in a "negative concordance" pattern. That is, when the QRS complex is negative, we may expect ST elevation. When the QRS is positive, ST depression is seen.