In this video, Dr. K K Aggarwal, President Heart Care Foundation of India and Group Editor in Chief MEDtalks, will discuss which is more serious LBB or RBB. He explains that right bundle block (RBB) is not an emergency and can get investigated over a period of time. But left bundle block (LBB) is abnormal and needs investigation immediately. He further adds that not to ignore LBB in ECG as it could be an acute myocardial infarct. In some patients, LBB could be the only sign of myocardial infarction if the patient is symptomatic.