Efficacy and safety of posterior wall isolation in persistent atrial fibrillation is modified by ablation energy source

Posterior wall isolation (PWI) is a common adjunct to pulmonary vein isolation (PVI) in catheter ablation of persistent atrial fibrillation (AF), yet randomized data have been discordant. Prior syntheses have pooled studies across ablation energy sources, which may obscure energy-specific effects. We examined whether the association of PWI with arrhythmia recurrence in persistent AF is modified by ablation energy source. We searched Ovid MEDLINE, Embase, and Web of Science for studies comparing PWI plus PVI with PVI alone in persistent AF. The primary endpoint was recurrence of all atrial tachyarrhythmias; secondary endpoints were recurrence of AF alone, procedural time, and procedural complications. Studies were stratified a priori by energy source (cryoballoon, radiofrequency [RF], and pulsed field [PF]). Odds ratios (OR) and mean differences were pooled using random-effects models, with subgroup differences assessed by the test for interaction. Twenty-two studies with 4400 patients with persistent AF (2029 PWI and PVI, 2371 PVI alone) were included. Compared with PVI alone, PWI was associated with reduced recurrence of all atrial tachyarrhythmias overall (OR 0.54, 95% CI 0.40-0.73), but the effect differed by energy source (test for subgroup differences p = 0.0006): cryoballoon OR 0.34 (95% CI 0.26-0.43), RF OR 0.67 (95% CI 0.43-1.04), and PF OR 0.96 (95% CI 0.55-1.70). A concordant pattern was observed for recurrence of AF alone (overall OR 0.36, 95% CI 0.25-0.51). PWI was associated with longer procedural times, with a graded effect across energies (cryoballoon mean difference 51.1 min; p = 0.007 for subgroup differences). Procedural complications did not differ between groups overall (OR 1.29, 95% CI 0.92-1.82) or by energy source (p = 0.49). In persistent AF, the association of PWI with freedom from atrial arrhythmia was concentrated in cryoballoon-based ablation and was not evident with RF or PF, without an excess of complications. These findings suggest that the conflicting literature on PWI may be explained, in part, by differences in ablation energy source rather than by the anatomic target alone. Because energy source is partly confounded with study design and the cryoballoon evidence rests on few randomized trials, this association is hypothesis-generating and merits evaluation in energy-specific randomized trials. No benefit was observed in the pulsed field ablation stratum, the modality in which adjunctive PWI is now most commonly performed, so its routine use may not confer the benefit reported with earlier energy sources.