Box lesion or bi-atrial lesion set for atrial fibrillation during thoracoscopic epicardial ablation

OBJECTIVES: Thoracoscopic epicardial ablation with a limited lesion set led to suboptimal results for advanced paroxysmal atrial fibrillation (AF) or persistent AF. Whether additional right atrial lesions improve the result is unclear. METHODS: We conducted a retrospective study involving 80 consecutive patients with paroxysmal or persistent AF, left atrial (LA) dilation (LA diameter >40 mm) and failed prior interventional ablation (40 patients, 50%) who underwent thoracoscopic epicardial ablation with box lesions (36 patients) or bi-atrial (BA) lesion (44 patients) in our institution. Freedom from atrial tachyarrhythmias after the procedures was compared between the box lesion group and BA lesion group. RESULTS: Baseline differences included more patients with persistent AF (86.4% vs 47.2%) and larger left atrium [48.00 (44.00-50.75) vs 42.00 (41.25-44.00) mm] in the BA lesion group. There was no difference in procedural complications between the 2 groups. After a mean follow-up of 32 months, the freedom from atrial tachyarrhythmias off antiarrhythmic drugs at 6, 12 and 24 months was 77.2%, 77.2% and 77.2% in the BA lesion group and 69.4%, 50.0% and 40.6% in the box lesion group, respectively (P = 0.006). After adjustment for sex, age, body mass index, LA diameter, AF type, history of AF, and previous interventional ablation, BA lesion was an independent predictor of lower atrial tachyarrhythmia recurrence (hazard ratio 0.447, 95% confidential interval 0.208-0.963; P = 0.040). CONCLUSIONS: Compared with the box lesion set, thoracoscopic epicardial ablation with BA lesion sets might provide better freedom from atrial tachyarrhythmias for paroxysmal or persistent AF with LA dilation. Randomized control trials are warranted to confirm the benefit of BA lesion sets in these patients.