OBJECTIVES: The objective of this study was to assess the spatial distribution of atrial ectopic foci potentially triggering recurrent atrial tachyarrhythmias after electrical cardioversion of long-standing atrial fibrillation (AF). BACKGROUND: It remains unknown whether targeted ablation of atrial ectopic foci concentrated in the pulmonary veins is feasible in patients with long-standing AF as it is in patients with paroxysmal AF. METHODS: Two basket electrodes (32 bipoles on each eight splines) were positioned in the right and left atrium to identify the earliest endocardial activation sites of atrial ectopic foci emerging immediately after external electrical cardioversion of long-standing AF, before and after intravenous administration of dl-sotalol (16 patients) and propafenone (16 patients). RESULTS: Before the use of antiarrhythmics, 91 distinct atrial ectopic foci were recognized after cardioversion. In 69 of the 91 foci, the earliest sites of presystolic atrial activation could be identified. Left atrial posterior (16 foci), left atrial anterior (11 foci) and right atrial posterior regions (13 foci) appeared to be prevalent. However, atrial ectopies from the remaining atrial regions (29 foci) were not uncommon. After adding dl-sotalol or propafenone, only 64 atrial ectopic foci were recognized after cardioversion; 50 of those were identifiable at the earliest activation sites. The scattered pattern of spatial distribution of the atrial ectopic foci was virtually unchanged. CONCLUSIONS: Atrial ectopic foci potentially triggering the recurrence of atrial tachyarrhythmias after successful electrical cardioversion of long-standing AF were scattered in spatial distribution and multiple in production, possibly rendering difficult the targeted ablation approach.
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