Key result
Modified box isolation linked to ~31-point lower AF recurrence vs PVI in LA >45 mm.
Why the study?
The efficacy of left atrial posterior wall isolation (LAPI) with LA roof and bottom lines following conventional pulmonary vein isolation (PVI) is unclear, motivating a comparison of modified box isolation (MBI) with PVI alone.
Does modified box isolation (MBI) reduce atrial fibrillation recurrence compared to conventional pulmonary vein isolation (PVI) alone in patients undergoing AF radiofrequency ablation, particularly those with left atrial enlargement?
Observational (n=198)
Does modified box isolation (MBI) reduce atrial fibrillation recurrence compared to conventional pulmonary vein isolation (PVI) alone in patients undergoing AF radiofrequency ablation, particularly those with left atrial enlargement?
Answers are grounded in this paper and cite their sources.
Modified box isolation is associated with lower AF recurrence and higher pulmonary vein isolation durability compared to conventional PVI alone specifically in patients with left atrial enlargement (>45 mm).
Background The efficacy of left atrial posterior wall isolation (LAPI) with LA roof and bottom lines following conventional pulmonary vein isolation (PVI) is unclear. The aim of this retrospective study was to compare modified box isolation (MBI), a unique LAPI technique wherein the left and right isolation lines are extended and connected to the posterior wall (PW) during PVI, with PVI alone. Methods The study included 198 patients who underwent atrial fibrillation (AF) radiofrequency ablation between January 2021 and December 2022 (57 with paroxysmal AF; age, 66±9 years; 149 males). MBI was performed if the PW design line of the left PV was located near the oesophagus and if the PW design lines of the left and right PVs were in proximity. Following circumferential ablation, a high-density mapping catheter was used to assess epicardial connections (ECs). Results A total of 77 and 121 patients underwent MBI and PVI, respectively. The MBI group required a significantly higher number of additional EC ablations for isolation than the PVI group (20.8±15.0 vs. 14.8±15.2; p<0.01), consistent with the greater number of ipsilateral PVs requiring isolation (1.4±0.7 vs. 1.1±0.8; p<0.01). At follow-up (495±246 days), 43 patients who did not receive antiarrhythmic drugs experienced AF recurrence. Recurrence was compared between patients with normal (≤45 mm; 73%) and enlarged LA diameters (>45 mm; 27%). Patients with LA diameters of >45 mm showed lower recurrence in the MBI group than in the PVI group (11% vs. 42%, p=0.02). However, no significant difference in recurrence rates was observed between groups for patients with LA diameters of ≤45 mm (20% vs. 16%, p=0.55). Among the 26 of 43 patients with AF recurrence undergoing repeated ablation, PV reconnection (i.e., lower PVI durability) was less frequent in the MBI group than in the PVI group (15% vs. 47%, p=0.02). Conclusions MBI was associated with better AF ablation outcomes and higher PVI durability in patients with LA enlargement. Higher PVI durability in the MBI group may be attributed to additional EC ablation.
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Ninomiya et al. (2026) conducted an observational in Atrial fibrillation (n=198). Modified box isolation (MBI) vs. Conventional pulmonary vein isolation (PVI) alone was evaluated on Atrial fibrillation recurrence in patients with enlarged left atrial diameters (>45 mm) (p=0.02). Modified box isolation was associated with lower AF recurrence than PVI alone in patients with LA diameters >45 mm (11% vs. 42%, p=0.02).
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