Relationship Between Nonuniform Isochrone‐Area in Late Activation Mapping and Arrhythmogenic Substrates Related to Atrial Fibrillation

INTRODUCTION: Arrhythmogenic substrates within the atrial myocardium may contribute to the initiation of atrial fibrillation (AF). The relationship between nonuniform isochrone-areas in late activation mapping and arrhythmogenic substrates remains undetermined. METHODS: Sixty-two patients (66 ± 10 years, 47 males, non-paroxysmal AF [n = 30], second ablation procedure [n = 8]) who undergoing catheter ablation for AF were enrolled. High-density left atrial (LA) activation mapping was performed during atrial pacing after pulmonary vein (PV) isolation. Late activation mapping was retrospectively reconstructed. Nonuniform isochrone-areas were defined as regions of nonuniform and mottled conduction-zones characterized by the crowding of ≥ 3 color-isochrones within a 1-cm radius in late activation mapping. The relationship between nonuniform isochrone-areas and arrhythmogenic substrates associated with AF was evaluated. RESULTS: Non-PV triggers were identified in 11 patients (AF-triggers:12; short runs of premature atrial complexes:4), located in the LA wall (posterior:7; anterior:6; septum:2; roof:1). Patients with non-PV triggers had significantly more nonuniform isochrone-areas than those without (median [interquartile range] 5.0 [3.0-6.0] vs. 2.0 [1.0-4.0], p < 0.001). In multivariate logistic analysis for the presence of non-PV triggers, after adjusting for confounders such as non-paroxysmal AF, heart failure-history, and presence of low-voltage areas, the presence of nonuniform isochrone-areas on the LA low-posterior wall was an independent indicator for the presence of non-PV triggers (odds ratio: 6.9 [95% CI:1.1-44.1], p = 0.040). Of the 52 nonuniform isochrone-areas observed in the 11 patients with non-PV triggers, 20 areas corresponded to non-PV trigger sites. CONCLUSION: Identification of nonuniform isochrone-areas located on LA low-posterior wall in late activation mapping may indicate the potential source for non-PV triggers.