In order to emphasize the fact that the changes of LBBB are usually purely electrical and not necessarily due to ischemia injury or infarction we will show another example of complete LBBB (ECG below). In this case, the patient's LBBB disappeared with transient slowing of the heart rate and a single beat is recorded which is entirely normal. The changes which suggested "ischemia", "injury" or "infarction" have abruptly disappeared, but they return with the restoration of the LBBB. Very impressive!

So remember the Hippocratic dictum of "Do no harm." and be very conservative about your interpretation of the changes seen with complete LBBB. In future cases we will demonstrate how acute myocardial infarction can be suspected and at times even confirmed electrocardiographically in patients with complete LBBB. However, that is a seperate topic entirely.