Focal Activations Detected by an Automated Mapping System: Insights From Contralateral Atrial Burst Pacing

The diagnostic performance of CARTO FINDER system for repetitive focal activations (FAs) that may sustain atrial fibrillation (AF) remains under debate.

In this prospective singlecenter study, we evaluated FAs detected by the mapping system during contralateral atrial burst pacing (CLABP) in sinus rhythm (SR) and during AF to characterize their features and potential underlying mechanisms. Protocol 1: The left atrium (LA) and right atrium (RA) were sequentially mapped during CLABP, delivered from the right atrial appendage (RAA) during LA mapping and from the left atrial appendage (LAA) during RA mapping. Protocol 2: Both atria were mapped in AF, and FA sites were partially remapped during CLABP after SR restoration to assess overlap. Mean cycle length (mCL) and its standard deviation (CL-Std) during AF were compared between overlapping and non-overlapping sites.

In Protocol 1, FAs were detected in LA roof/LA septum/LAA/RAA (100%), anterior LA/RA septum (92%), and posterior LA/lateral RA (83%). In Protocol 2, detection sites included lateral LA/LAA/lateral RA/posterior RA/RA septum/RAA (100%), inferior LA (89%), and posterior LA (78%). During CLABP and AF, FAs were frequently and similarly detected in LAA/RAA, septal regions, posterior LA/inferior LA, and lateral RA. Although overlapping sites showed longer mCL (169.8 ± 15.1 vs. 161.8 ± 12.7 ms; p = 0.002) and higher CL-Std (20.1 ± 7.8 vs. 17.1 ± 5.0 ms; p = 0.02), neither predicted overlap.

A substantial portion of FAs detected by the mapping system may arise from complex activation pathways rather than focal sources, delineating interpretive gaps and outlining targets for subsequent refinement.