Abstract
Background: Multielectrode mapping (MEM) of extra-pulmonary vein (PV) targeted ablation of persistent atrial fibrillation (PsAF) drivers suffers from false positives. Early studies suggest that true AF drivers are anchored to arrhythmogenic fibrosis, which can be visualized with late gadolinium enhanced (LGE) cardiac magnetic resonance (CMR) to distinguish them from false positive drivers on MEM. Hypothesis: Driver regions integral to AF correlate with high atrial fibrosis; therefore, ablation of MEM-defined drivers within fibrotic regions may lead to better outcomes than MEM-defined drivers outside fibrosis. Methods: Pre-ablation, 10 PsAF patients (Pts) (70% male; 65±11 y/o) underwent LGE-CMR at 3T (0.625x0.625x1.25mm 3 , 0.2mmol/kg gadolinium). During ablation, MEM (64-electrode basket catheter) was used to identify Pt-specific extra-PV drivers. Retrospectively, both left (LA) and right atria (RA) were analyzed with atria-specific fibrosis masks (voxels exceeding an intensity of 3-3.5 standard deviations above the mean intensity of nonfibrotic atrial wall). Ablated drivers were classified as fibrotic driver (dense or patchy) or nonfibrotic driver by LGE-CMR and MEM correlation. Results: 30 drivers were ablated in 10 PsAF Pts (2±1 LA drivers/Pt, 1±1 RA drivers/Pt) and were classified if anchored to dense (n=16, 45.4±31.7%, 2.6±1.8cm 2 ), patchy (n=11, 8.9±13.5%, 2.0±2.5cm 2 ), or no (n=3, 2.3±2.0%) fibrosis. At follow-up (13±7 mos), 7/10 Pts remained free from AF and atrial flutter, all of whom had at least one dense fibrosis driver ablated and all but 1 Pt had ablations limited to fibrotic drivers. 2/3 patients with failure at follow-up had a nonfibrotic driver ablated. Conclusion: Our results suggest that limiting ablation of AF drivers to those anchored to dense fibrotic substrate may improve long-term AF-free survival. Identification of Pt-specific fibrotic substrate by LGE-CMR may help specificity of MEM ablation targets for successful PsAF treatment.
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