Late‐gadolinium enhancement properties associated with atrial fibrillation rotors in patients with persistent atrial fibrillation

Abstract

Background A computational model demonstrated that atrial fibrillation (AF) rotors could be distributed in patchy late‐gadolinium enhancement (LGE) areas 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 LGE properties of AF rotors in patients with persistent AF. Methods A total of 287 segments in 15 patients with persistent AF (long‐standing 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). The properties of the LGE areas were assessed using the LGE heterogeneity and the density which was evaluated by the entropy (LGE‐entropy) and the 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 = .001). No NPAs were found at segments with an LGE‐volume ratio of >50% regardless of the LGE‐entropy. Of five patients with AF recurrence, NPAs outside the PV antrum were not ablated in three patients and the remaining NPAs were ablated, but their LGE‐entropy and LGE‐volume ratio were low. Conclusion AF rotors are mostly distributed in relatively weak and much more heterogenous LGE areas.

The Impact of the Atrial Wall Thickness in Less Late-Gadolinium Enhancement Areas on Atrial Fibrillation Drivers in Persistent Atrial Fibrillation Patients

“…As we previously reported, the AF drivers were mainly be located in heterogenous LGE areas, which could be detected by LGE-MRI. 7 Preprocedural LGE-MRI could evaluate the LA wall thickness as well as LGE areas precisely and would be useful to predict the AF drivers in the lesser LGE area. This would help in planning where to ablate in addition to the PVI at a point before the ablation procedure and might reduce frequent electrophysiological mapping.…”

“…The details of the measurement can be found in the previous publication. 7 In this study, the areas with an LGE-volume ratio of < 10% were defined as lesser LGE areas, and heterogenous LGE areas were defined as areas with an LGE-volume ratio of > 10%.…”

“…The detail of this mapping system was previously described. 7 ExTRa Mapping was applied to persistent AF patients and as a result, each wave dynamics were classified into 3 patterns, meandering rotors (MRs), multiple wavelets (MWs), and planar wave. Planar wave propagation was defined as passive activation, whereas MR and MW were defined as non-passive activations.…”

“…However, AF drivers are also observed in lesser LGE areas. 7 Roy et al reported that the AWT gradients played an important role in anchoring AF drivers in the absence of fibrosis. 8 In an optical mapping ex vivo study of perfused right atria from explanted diseased human hearts, activation delays between the endocardium and epicardium during atrial pacing were more prominent in areas with an increased wall thickness, transmural fiber orientation angle gradient, and interstitial fibrosis.…”

“…However, some of them were also found in lesser LGE areas. 7 This has implied that there are other possible structural factors associated with AF drivers. A previous computer simulation study demonstrated the role of the atrial wall thickness (AWT) as a substrate for AF drivers and marker for the identification of AF driver locations in patient-specific atria, and the AWT gradients acted as anchoring points for AF drivers in the absence of fibrosis.…”