Clinical Implications of Adjunctive Posterior Wall Isolation According to Ablation Modality: A Subanalysis of the CORNERSTONE AF Trial

BACKGROUND Left atrial posterior wall isolation (LAPWI) is a common adjunctive ablation strategy for persistent or longstanding persistent atrial fibrillation. OBJECTIVE To investigate the impact of adjunctive LAPWI according to pulmonary vein isolation (PVI) ablation modality. METHODS This CORNERSTONE-AF randomized trial subanalysis compared 18-month outcomes between PVI alone (n=259) and PVI+LAPWI (n=254). The primary endpoint was freedom from atrial arrhythmia. Secondary endpoints included freedom from repeat ablation. Randomization was stratified by PVI ablation modality. RESULTS PVI was performed using radiofrequency and cryoballoon ablation in 384 and 129 patients, respectively. In the LAPWI group, the LAPWI area was significantly larger in the cryoballoon than in the radiofrequency subgroup. Additional LAPWI significantly prolonged procedure time without increasing fluoroscopy time in both subgroups. In the cryoballoon subgroup, 18-month freedom from atrial arrhythmia was numerically higher with LAPWI than with PVI alone (82.0% vs. 69.1%, P=0.163), whereas no difference was observed in the radiofrequency subgroup (80.5% vs. 79.4%, P=0.309). There was no treatment-by-modality interaction (P for interaction=0.64). Freedom from repeat ablation was higher with LAPWI in the cryoballoon subgroup (96.5% vs. 82.0%, P=0.029), but not in the radiofrequency subgroup (90.1% vs. 88.5%, P=0.210), without a significant treatment-by-modality interaction (P for interaction=0.17). Overall complication rates were similar between groups; symptomatic gastroparesis occurred in three patients in the radiofrequency LAPWI subgroup. CONCLUSIONS Adjunctive LAPWI did not significantly improve freedom from atrial arrhythmia with either ablation modality, with no significant treatment-by-modality interaction. The potentially favorable findings with LAPWI after cryoballoon PVI should be considered exploratory and hypothesis-generating.