Bifascicular block affects a substantial number of patients. It occurs in 1-2% of the adult population and the incidence increases with age. It is frequently associated with structural heart disease and fibrosis of the cardiac conduction system. Patients with underlying bifascicular block are at risk of progression to complete heart block. The rate of progression varies from 1 to 17%, and is more likely in symptomatic patients who present with syncope or pre-syncope1.
The European Society of Cardiology (ESC) and American College of Cardiology/Heart Rhythm Society (ACC/HRS) have both published guidelines on the evaluation and management of bifascicular block2,3.