Key result
Atrial segments with higher fibrotic heterogeneity and density (LGE-entropy >5.7 and LGE-volume ratio >10%) had a significantly higher incidence of AF rotors than other segments (30% vs 14%, p=0.001).
Why the study?
Computational models showed atrial fibrillation rotors could distribute in patchy fibrotic tissue as AF drivers, but this had not been validated in humans.
Are atrial fibrillation rotors associated with specific fibrotic tissue properties (heterogeneity and density) in patients with persistent AF?
Observational (n=15)
Are atrial fibrillation rotors associated with specific fibrotic tissue properties (heterogeneity and density) in patients with persistent AF?
AF rotors in patients with persistent AF are predominantly distributed in relatively weak and highly heterogeneous fibrotic tissue, validating previous computational models in humans.
May inform substrate mapping to heterogeneous fibrotic segments in persistent AF; leaves open whether targeting them improves ablation outcomes.
Background: A computational model demonstrated that atrial fibrillation (AF) rotors could be distributed in patchy fibrotic tissue and play an important role in AF drivers. However, this was not validated in humans. Objective: The purpose of this study was to evaluate the fibrotic tissue properties of AF rotors in patients with persistent AF. Methods: A total of 287 segments in 15 patients with persistent AF (longstanding persistent AF in 9 patients) that underwent AF ablation were assessed. Non-passively activated areas (NPAs), where rotational activation (AF rotor) was frequently observed, were detected by the novel real-time phase mapping (ExTRa Mapping). Atrial fibrosis was detected by late-gadolinium enhancement magnetic resonance imaging (LGE-MRI), and the fibrotic heterogeneity and density were assessed by the entropy (LGE-entropy) and volume ratio of the enhancement voxel (LGE-volume ratio), respectively. Results: NPAs were found in 61 (21%) of 287 segments and were mostly found around the pulmonary vein antrum. A receiver operating characteristic curve analysis yielded an optimal cutoff value of 5.7 and 10% for the LGE-entropy and LGE-volume ratio, respectively. The incidence of NPAs was significantly higher at segments with an LGE-entropy of >5.7 and LGE-volume ratio of >10% than at the other segments (38 [30%] of 126 vs. 23 [14%] of 161 segments, p = 0.001). No NPAs were found at segments with an LGE-volume ratio of >50% regardless of the LGE-entropy. Conclusion: AF rotors are mostly distributed in relatively weak and much more heterogenous fibrotic tissue.
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Nakamura et al. (2020) conducted an observational in Persistent atrial fibrillation (n=15). High fibrotic heterogeneity and density (LGE-entropy >5.7 and LGE-volume ratio >10%) vs. Other segments (lower fibrotic heterogeneity or density) was evaluated on Incidence of non-passively activated areas (NPAs) / AF rotors (p=0.001). Atrial segments with higher fibrotic heterogeneity and density (LGE-entropy >5.7 and LGE-volume ratio >10%) had a significantly higher incidence of AF rotors than other segments (30% vs 14%, p=0.001).
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