Local inhomogeneous conduction and non‐uniform anisotropism in a normal voltage atrial map

A patient with symptomatic persistent atrial fibrillation and recurrences after pulmonary vein isolation (PVI) underwent a second ablation procedure. The PVs were found isolated and the left atrial substrate tissue was mapped. During sinus rhythm, the voltage map resulted in a normal range (>0,5mV) while a map of EGMs durations revealed an area presenting prolonged EGMs (>45 ms) in the anterior region. The activation map of this area demonstrated abnormal conduction and a non-uniform anisotropism when compared with areas in which EGM’s normal durations were recorded. The EGMs dura- tion map may offer additional clinical information on the areas presenting abnormal conduction predisposing arrhythmias maintenance in patients suffering from persistent atrial fibrillation.