Introduction
Recurrent atrial fibrillation (AF) after catheter ablation (CA) is a common clinical problem. Main cause of AF recurrence is pulmonary vein (PV) reconnection. Nevertheless, some patients experience a recurrence even after complete PV isolation. These outcomes are likely explained by the development of an atrial arrhythmogenic substrate and a non-PV trigger. The previous study has failed to demonstrate the efficacy of CA with substrate modification for AF.1 Recent reports suggested that ablation for low voltage area (LVA) in addition to PV isolation improved procedural outcomes in patients with AF.2 However, these strategies for LVA have insufficient success rate.
It is known that atrial remodeling due to AF causes an increase in fibrosis, which is associated with a reduction in conduction velocity, and a consequent increase in susceptibility to AF.3Regions of slowed conduction have classically been considered markers of disease tissue that enable arrhythmia perpetuation, and that may sustain atrial arrhythmia.4 Previous studies reported that fibrosis of the left atrium (LA), resulting in conduction abnormality, appears to be associated with higher recurrence rates.5 Recently, Mouws et al reported that conduction abnormalities were associated with AF.6 However, little has been reported on the abnormal conduction zone (ACZ) of the LA.
The Advisor HD grid mapping catheter (HD Grid, Abbott) was released in 2019. Using the HD Grid can create a detailed voltage map and local activation map. Furthermore, previous studies suggested that AF itself and other factors, such as compression from the external structures, can promote atrial remodeling. Hori et al investigated the relationship between the contact area (CoA) of the LA with external anatomical structures in 22 AF patients. They indicated that LVA had a strong association with CoA.7 Although the ACZ may be regions of interest in sustained AF, detailed electrophysiological studies describing the nature of the ACZ are lacking. We focused on the ACZ, and investigated the characteristics of the ACZ and whether the ACZ was related to the LVA or the LA anatomical CoAs with other organs in patients with AF.