Fractionated non-pulmonary vein triggers contribute to spontaneous activity and initiating and maintaining paroxysmal atrial fibrillation: A case report.

Pulmonary vein (PV) antrum isolation (PVAI) that involves electrically isolating PV foci is a useful treatment strategy for atrial fibrillation (AF). However, non-PV triggers during/after the PVAI are observed in approximately 30 % of AF cases, contributing to AF recurrence. We present the case of an 84-year-old woman who underwent ablation of recurrent symptomatic paroxysmal AF in our hospital. AF was easily induced following spontaneous activity (SA) from non-PV triggers even after completing the PVAI, left atrial posterior wall isolation with roof and bottom lines, and superior vena cava isolation. Interestingly, the area of the earliest activation site of the SAs initiating AF and that with a fractionation mapping score of ≥4 corresponded. AF was steadily terminated during ablation of this fractionated area, and the programmed stimulation could no longer induce any SA or AF. This case report demonstrated that the area with a score of ≥4 points on the fractionation mapping calculated by EnSite™ (Abbott, Abbott Park, IL, USA) during sinus rhythm may contribute to the initiation and maintenance of paroxysmal AF. In patients whose AF does not resolve during ablation, physicians may consider performing an additional targeted ablation of the area with a fractionation mapping score of ≥4, even in patients with paroxysmal AF. Learning objective: The area with a fractionation mapping score of ≥4 calculated by EnSite™ during sinus rhythm might play an important role in producing spontaneous activities and initiating and maintaining paroxysmal atrial fibrillation (AF). Thus, if the AF does not terminate during ablation, physicians should consider performing an additional targeted ablation of the area with a fractionation mapping score of ≥4, even if it is paroxysmal.