PVI-only is not enough for all patients with persistent AF: A FLOW-AF subgroup analysis

Background: Since the Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial Part II (STAR-AF II), there has been a trend toward pulmonary vein isolation (PVI)-only ablation strategies for persistent atrial fibrillation (PeAF). Electrographic flow (EGF) mapping can identify active sources of atrial fibrillation (AF) and estimate the electrographic flow consistency (EGFC) of wavefront propagation through substrate, revealing functional AF mechanisms.

Objective: We sought to examine the success of a PVI-only ablation strategy for a redo PeAF/longstanding PeAF population.

Methods: Electrographic Flow-Guided Ablation in Redo Patients With Persistent Atrial Fibrillation (FLOW-AF [NCT04473963]) prospectively enrolled patients with nonparoxysmal AF undergoing redo ablation at 4 centers. One-minute EGF recordings using 64-pole basket catheters were obtained both pre-PVI and post-PVI following a 20-minute wait and confirmation of electrical isolation of veins. Patients with EGF-identified sources were randomized 1:1 to EGF-guided source ablation vs PVI-only. Patients with no sources were not randomized and mostly received PVI only.

Results: Study of 85 patients enrolled 24 with EGF-identified sources randomized to PVI only and 23 with no sources receiving PVI only. Of these 47 patients, those with sources (Group 2) had different clinical characteristics including older age and higher CHA₂DS₂-VASc scores compared with those with no sources (Group 1). After PVI only, Group 1 had 70% (16 of 23) freedom from recurrent AF (FFAF) within 1 year vs Group 2 with 35% (8 of 23), P = .018. In addition, patients with high electrographic flow consistency (EGFC) indicative of healthy or normal substrate had 67% (10 of 15) FFAF vs 45% (14 of 31) in those with low EGFC suggestive of abnormal substrate, P = .011.

Conclusion: Success rates in no-sources patients receiving PVI only are better than in those with sources randomized to PVI only. For the clinically heterogenous population of patients with PeAF, the presence of EGF-identified sources matters clinically, and PVI only will not be enough for all patients.