LVAs detected using the HDG
An increased amount of fibrosis as detected by LA voltage mapping has been shown to be a predictor of AF/AT recurrence after AF ablation.5,6,7 The extent of the LVAs was categorized on the basis of the LA fibrosis grade evaluated by delayed-enhancement magnetic resonance imaging (MRI).20,21 However, the definition of the LVAs and their correlation with histological fibrosis remains controversial, because the bipolar voltage amplitudes depend on the electrode orientation relative to the direction of the wavefront, electrode length, interelectrode spacing, and tissue contact.22 Furthermore, the HDG when used for bipolar recording can record not only the parallel but also the perpendicular activation to the splines, which differs from conventional mapping.23 Therefore, the HD grid could create high density maps to define anatomical substrates regardless of the direction of the activation. In this study, the HDG drastically decreased the extent of the LVA. The HDG may improve the directional sensitivity and exclude any false low-voltages, and can detect the AF substrate more accurately, which would lead to a more effective ablation strategy.23