Physiologic resynchronization therapy: a case of his bundle pacing reversing physiologic conduction in a patient with CHF and LBBB during 2 years of observation.

This is a case of a patient with congestive heart failure and left bundle branch block who was referred for cardiac resynchronization therapy implantation. Instead, a His bundle pacing was achieved with a narrow QRS complex. During 27 months of observation, the patient improved dramatically from NYHA class IV to I. Echo parameters improved significantly the LV diameter from 75/50 to 60/40 mm, EF from 28 to 50%, and mitral regurgitation from 4 to 2°.