Identification and Ablation of an Incidental Concealed Accessory Pathway During Atrial Fibrillation Ablation.

A 69-year-old man with persistent atrial fibrillation (AF) experiencing recurrences of suspected paroxysmal atrial tachycardia was referred for repeat ablation. He had previously undergone pulmonary vein isolation in 2016. He was suspected to be experiencing a tachycardia involving the mitral isthmus or left-sided veins initially; however, electroanatomic mapping did not reveal a circuit involving these structures. Instead, a focal arrhythmia with the earliest signal on the anterolateral mitral valve annulus was noted. Catheter manipulation in this region consistently terminated the tachycardia.