Recurrence as isthmus-related atrial tachycardia: A cautionary point of low-voltage area homogenization of persistent atrial fibrillation.

A 66-year-old female underwent persistent atrial fibrillation ablation. After pulmonary vein isolation and homogenization of low-voltage areas (LVAs), atrial tachycardia (AT) was not induced at the first session; however, it recurred one year after the procedure. During the second session, the extensive LVAs were distributed in the same area of the left atrial anterior wall and expanded possibly due to the previous LVA homogenization. The activation map revealed a macroreentrant AT circuit with the critical isthmus between the isolated right superior pulmonary vein and homogenized LVAs. Although the Ripple map algorithm failed to visualize dynamic bars, extremely low voltage and fractionated potentials (amplitude, 0.04 mV) were observed at the isthmus. Currently, there are various procedural endpoints of LVA-guided ablation (e.g. local electrogram reduction > 50 % or <0.1 mV in amplitude). In this case, incomplete transmural lesions may have led to slow conduction, which could have become an AT substrate. In cases with extensive LVAs on the left atrial anterior wall, eliminating any potential channels may be important for preventing future iatrogenic ATs. LVA-guided ablation should be performed on an individual basis, considering the potential benefits and harms based on the extent and location of LVAs. Learning objective: Currently, the procedural endpoint of low-voltage area (LVA)-guided ablation varies across studies. Because any low-voltage potentials, except scars, can cause slow conduction, LVA-guided ablation with an endpoint of local electrogram voltage reduction can unintentionally generate an iatrogenic slow conduction isthmus. LVA-guided ablation should be individually performed, considering the potential benefits and harms based on the extent and location of LVAs.