Post-Transcatheter Aortic Valve Implantation QRS Interval Alternans: What Is the Mechanism?

Alternating bundle branch block is a significant conduction abnormality observed after transcatheter aortic valve replacement. This electrocardiographic finding indicates progressive conduction system disease, often on a background of preexisting conduction disturbances (eg, right bundle branch block). However, the presence of alternating fascicular block is very rare. The presence of alternating fascicular blocks suggests an increased risk for complete heart block, frequently necessitating permanent pacemaker implantation to prevent life-threatening arrhythmias.