Asymptomatic patients with isolated left bundle branch block and no underlying heart disease require no treatment. Routine follow-up is required in such patients. In symptomatic patients treatment is directed at the underlying cause of left bundle branch block, such as ST elevation myocardial infarction. Patients with syncope and LBBB may have a rhythm disturbance that requires a pacemaker. Given the dys-ynchrony that occurs with left ventricular contractility, cardiac resynchronization therapy in heart failure patients may be of benefit.