Coupled Beats After AV Node Ablation: What is the Mechanism?

An 83 year old lady was highly symptomatic from paroxysmal Atrial Fibrillation (AF) despite numerous antiarrhythmic and rate-limiting medications. Given her preserved left ventricular function, a pace and ablate strategy was pursued. Ablation of the AV node proved challenging requiring 2 procedures with apparently stable AV block and regular escape at 40bpm after the first sitting. Persistent Right Bundle Branch Block (RBBB) was created prior to...