Fibrotic Tissue Properties associated with Atrial Fibrillation Rotors in
Patients with Persistent Atrial Fibrillation
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.