Conduction System Pacing Upgrade in Chronic Heart Failure with Severe Left Ventricular Dysfunction and Chronic Atrial Fibrillation.

Cardiac resynchronization therapy (CRT) is a standard treatment for patients with severe congestive heart failure. However, one-third of patients receiving CRT are non-responders. Conduction system pacing (CSP), including His-bundle pacing (HBP) and left bundle branch area pacing (LBBAP), has become an alternative to CRT therapy. Furthermore, CRT therapy with CSP has shown to be more effective than CRT alone. When an implantable cardiac defibrillator or CRT-defibrillator is implanted with CSP, the problem of which port the HBP lead and LBBAP lead should be connected to arises. We report 2 cases of upgrading to CRT with CSP by utilizing the atrial ports for HBP and LBBAP leads. The procedure is a simple, reasonable, and effective therapy for end-stage heart failure.