Underexplored energy reduction, posterior dosing constraints, and bundling effects in the PeAF-by-LAWT trial

The PeAF-by-LAWT randomized trial by Falasconi et al.¹ demonstrated that the tailoring of the ablation index (AI) to left atrial wall thickness (LAWT) achieved non-inferior 12-month arrhythmia-free survival compared with the CLOSE protocol while halving the combined radiofrequency (RF) time for the left and right pulmonary veins (14.4 vs. 28.6 min). Several underrecognized patterns and potential constraints—particularly those related to energy thresholds, posterior wall dosing, and procedural bundle effects—warrant closer scrutiny.

The magnitude of RF reduction without loss of first-pass isolation or change in the gap distribution challenges the assumption that uniformly high AI targets are necessary for durable pulmonary vein isolation.^2,3 This suggests a lower threshold for effective lesion creation, with the potential to reduce the myocardial thermal load and collateral injury. While these efficiency gains align with broader procedural safety goals⁴ and may facilitate workflow optimizations—such as earlier mobilization or same-day discharge in selected patients⁵—the absence of intraprocedural transmurality metrics or post-ablation endoscopy leaves lesion safety and depth unconfirmed.

The near-universal posterior wall–oesophagus overlap in the LAWT arm (94.9%) prompted AI downtitration to 300 in almost all affected segments; yet, 1-year efficacy was preserved.¹ This effectively resulted in personalized anterior dosing but standardized posterior under-dosing. Although this is consistent with evidence supporting energy modulation in thin-walled posterior tissue,^6,7 it also meant that circumferential LAWT-guided dosing was not fully tested. Given that posterior reconnection is a frequent recurrence mechanism,⁸ the long-term durability of such low-AI posterior lesions remains uncertain and should be evaluated with lesion-level follow-up.

An asymmetry in first-pass isolation—higher for the right pulmonary veins (RPVs) and slightly lower for the left pulmonary veins (LPVs)—was also observed.¹ The likely driver was the protocol’s mandatory RPV carina line, absent in CLOSE, rather than wall thickness–based titration alone. This underscores the primary limitation: the intervention was a procedural bundle incorporating LAWT-guided dosing, line relocation, oesophageal isodistance mapping, and the RPV carina line. Multiple concurrent modifications prevent the attribution of benefits to LAWT titration in isolation.

Additional unacknowledged weaknesses include limited generalizability due to moderate atrial dilation and low CHA₂DS₂-VASc scores in the study population, intermittent follow-up monitoring that risks missing asymptomatic recurrences, and conduct in high-volume centres with optimized imaging, anaesthesia, and ventilation protocols.^9,10 These conditions differ from typical practice environments, where patient complexity is greater and resources more variable.

Collectively, these patterns and gaps suggest that while substantial reductions in RF and AI are feasible without compromising short-term efficacy, the untested durability of low-AI posterior lesions and the confounding influence of bundled procedural changes require targeted trials isolating each component, with direct safety and durability assessments before broad clinical adoption.