Left Bundle Branch Pacing in Transthyretin Cardiac Amyloidosis and Alternating Bundle Branch Block.

Progressive conduction system disease affects patients with transthyretin cardiac amyloidosis, often requiring permanent pacing as the His-Purkinje system is affected. We present a case of left bundle branch pacing in a patient with transthyretin cardiac amyloidosis and infra-Hisian conduction disease with a favorable improvement in cardiac function and stable pacing thresholds. (Level of Difficulty: Intermediate.).