The patient was free from AF without any antiarrhythmic drugs during 18 months of follow-up. AF could not be induced by any atrial drive train with high doses of isoproterenol. After a couple of ablations at the site, AF did not occur even after cardioversion. After cardioversion, similar high-frequency activation inducing AF was recognized by the radiofrequency catheter ( Figure 3B). After tagging the site of earliest activation (2 and 3 of the C-spline, Figure 3A), a radiofrequency catheter was placed at the same area. This finding implied that the exact non-PV foci were situated within this high-density grid catheter facing the prominent Eustachian ridge. Furthermore, the earliest activation site of the first ectopic beat was the C-spline of the high-density grid catheter, neither the A-spline nor the D-spline. A few seconds later, local ectopic beats with rapid firing of a mean cycle length of 120 ms triggered sustained AF. After cardioversion, a single atrial ectopy occurred with a short interval of 170 ms conducting to the surrounding right atrium in 2:1 fashion, suggesting the presence of an intra-atrial conduction block ( Figure 2A). Therefore, the high-density grid catheter was placed towards this prominent Eustachian ridge.
An enhanced computed tomography (CT) scan image recorded before the procedure revealed a prominent Eustachian ridge ( Figure 1) at that area. The earliest activation site was depicted in the anterior direction of the right atrium in this way. Using a high-density grid catheter, the site of origin was mapped precisely with a minimum number of cardioversions, as shown in the Supplemental Figure. The sequence of the first beat triggering AF was always the same, showing the origin close to the lower right atrial septum.
Then, we placed a wide halo catheter with duodecapolar electrodes in the whole right atrium and a ring catheter at the left atrial septum so as to map the right atrial free wall and both atrial septums simultaneously. Despite repeated electrical cardioversions, AF recurred in the same manner.
However, after a few seconds, AF recurred. After PVs and left atrial posterior wall (LAPW) isolation were performed during AF, electrical cardioversion converted AF to sinus rhythm. Echocardiography showed a normal ejection fraction and a left atrial diameter of 44 mm. A 50-year-old man was referred for catheter ablation owing to persistent AF.
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