Small solitary atrial fractionated electrogram zone as a novel ablation target for persistent atrial fibrillation

Introduction: Various adjunctive approaches to pulmonary vein isolation (PVI) have been attempted for persistent atrial fibrillation (perAF) and longstanding persistent AF (ls-perAF). We aimed to identify the novel zones responsible for perpetuation of AF.

Methods: To identify novel zones acting as a source of perAF and ls-perAF after PVI/re-PVI, we performed fractionation mapping in 258 consecutive patients with perAF (n = 207) and ls-perAF (n = 51) in whom PVI/re-PVI failed to restore sinus rhythm.

Results: In 15 patients with perAF (5.8%: 15/258), fractionation mapping identified a small solitary zone (<1 cm² ) with high-frequency and irregular waves, showing fractionated electrograms (EGM). We defined this zone as the small solitary atrial fractionated EGM (SAFE) zone. The small SAFE zone was surrounded characteristically by a homogeneous area showing relatively organized activation with nonrapid and nonfractionated waves. Only one small SAFE zone was detected in each patient. This characteristic electrical phenomenon was observed stably during the procedure until ablation. AF duration, (defined as the duration between initial detection of AF and the current ablation) was longer in patients with the small SAFE zone than in those without (median, [25 and 75 percentiles]; 5.0 [3.5, 7.0] vs. 1.1 [1.0, 4.0] years, p = .0008). Longer AF cycle length was observed in patients with the small SAFE zone than in those without. The ablation of the small SAFE zone terminated AF in all 15 patients without any need for other ablations. AF/atrial tachycardia-free rate at follow-up was 93% (14/15) at 6 months, 87% (13/15) at 1 year, and 60% (9/15) at 2 years.

Conclusions: Using fractionation mapping, this study identified a small SAFE zone surrounded characteristically by a homogeneous, relatively organized, low-excitability EGM lesion. The ablation of the small SAFE zone terminated AF in all patients, demonstrating it as a substrate for perpetuated AF. Our findings provide novel ablation targets in perAF patients with prolonged AF duration. Further studies to confirm the present results are warranted.