Substrate properties in sinus rhythm underlie dominant frequency patterns during atrial fibrillation
S Ros, J Lopez-Doriga, M Munoz-Perez, I Martin-Martinez, L Gonzalez, A M Climent, M S Guillem, E Gonzalez-Torrecilla, P Avila, A Carta-Bergaz, J Bermejo, A Arenal, G Rios-Munoz, F AtienzaAbstract
Background
Atrial fibrillation (AF) reflects complex structural and electrophysiological remodelling, yet the link between substrate properties in sinus rhythm (SR) and AF dynamics remains unclear.
Objective
To determine how atrial conduction and voltage features measured in SR relate to dominant frequency (DF) patterns during AF.
Methods
Electroanatomical mapping was performed in 17 persistent AF patients (64 ± 16 years; 16 male; 6 redo) undergoing pulmonary vein isolation (10 spontaneous, 7 induced AF). AF and SR maps were obtained. In SR, voltage and isochronal activation maps were acquired during distal coronary sinus pacing at 300 and 600 ms cycle lengths (CLs). Custom software computed "true deceleration" (TD) maps identifying the areas with the largest continuous decline in conduction velocity across consecutive isochrones. During AF, 30-second electrograms were analysed to compute DFs (180 ± 89 recordings per patient). Each DF was correlated with local SR voltage and conduction metrics within a 1 cm radius, excluding areas with insufficient mapping density.
Results
DF values did not differ between induced and basal AF (p = 0.145). Both voltage magnitude and heterogeneity in SR were independently associated with higher DF (p < 0.001) regardless of pacing CL. Conversely, regions with higher TD exhibited lower DF (p = 0.002). Interestingly, the DF-TD relationship diminished with distance from the pacing site (p = 0.002), becoming non-significant beyond 55.6 mm at 600 ms CL and 67.3 mm at 300 ms.
Conclusion
AF activation rates are strongly determined by substrate characteristics measurable in SR. Regions with high voltage and heterogeneous voltage distribution showed faster AF activity, whereas marked true deceleration was associated with slower AF dynamics. Importantly, the pacing-site dependence of TD highlights its dynamic, functional nature, capturing spatially confined conduction reserve that voltage alone cannot describe. Integrating both voltage and TD mapping may better characterize atrial substrate and guide individualized ablation strategies.