Although bundle branch block itself often requires no direct treatment, you'll need treatment of any underlying health condition that could cause bundle branch block, such as coronary heart disease. (mayoclinic.com)

Usually a person with bundle branch block shows no symptoms, but this block shows up on the electrocardiogram (ECG or EKG) as an abnormality. If you have bundle branch block, it may have only been noticed when you had an ECG. (American Heart Association, Inc.)

As your doctor points out, bundle branch block is a common condition and in about half of cases there's no obvious cause. Some of the known causes are coronary artery disease, inflammation of the heart muscle and an overdose of digitalis type drugs. (bbc.co.uk)