Investigating the spectral characteristics of human persistent atrial fibrillation using non-contact multisite mapping: a prospective ablation study

The electrophysiological mechanism underlying persistent atrial fibrillation (persAF) is incompletely understood and compounded by the limitations of current point-by-point mapping technologies, generating uncertainty regarding the optimal ablation strategy. Spectral mapping allows derivation of dominant frequency (DF) and regularity index (RI), which have been suggested as indicators of AF sources. The basis of the current work combines this signal processing technique with a commercially available panoramic non-contact mapping catheter in order to analyse, ablate, and further understand AF behaviour.

In this clinical translational pilot study, DF maps were created from 30 seconds of continuous human persAF data via a bespoke user interface designed and implemented specifically for this work. Prospective ablation of dynamically-detected highest DF (HDF) was undertaken safely and efficaciously. Isopotential maps of HDF areas showed highly correlated focal breakout and exit but no other significant activation patterns, supportive of spatially conserved multi-layer behaviour at these areas.

Using 5 minute periods of AF data, a strong inverse relationship between DF variability and RI was demonstrated. HDF and highest RI were associated with lesion ablation outcome only when cumulative effects were excluded, and AF disorganization was associated with low pre-ablation mean DF and RI.

Stable DF episodes were investigated as a temporal marker of AF substrate. Such events were shown to be intermittent and spatially asynchronous but anatomically-anchored at a preferential activation rate. Consistent with our earlier findings, DF stability was found to drive periods of higher RI. These results are potentially compatible with a role for stable DF detection in identifying intermittent source behaviour in the both spatial and temporal dimensions. Stable DF difference divergence, where the same tissue could support more than one stable DF value, was related to lack of termination during substrate ablation, and may represent a novel marker of more functionally complex underlying substrate.