Abstract
BACKGROUND: Conduction disturbances are common after transcatheter aortic valve replacement (TAVR), whereas alternating bundle branch block reflects advanced conduction system disease. CASE SUMMARY: A 76-year-old man underwent TAVR with an initially normal postprocedural electrocardiogram (ECG). Six days later, he presented with syncope. The admission ECG demonstrated wide QRS complexes. A retrospective review of early 12-lead Holter monitoring revealed alternating bundle branch block. Conduction system pacing was performed. DISCUSSION: This case illustrates how dynamic conduction instability after TAVR may remain undetected on a resting ECG and require extended rhythm assessment for early recognition. TAKE-HOME MESSAGES: Extended rhythm surveillance after TAVR can detect transient or intermittent conduction abnormalities not apparent on a standard ECG. Early identification of such changes may enable timely electrophysiological evaluation and appropriate device therapy.