Abstract 10039: Functional Properties of Complex Fractionated Atrial Electrograms During Atrial Fibrillation Can be Explained by Structural Remodeling: A Computational Study
Introduction: Electrogram-based catheter ablation, targeting complex fractionated atrial electrograms (CFAE), is empirically known to be effective in halting chronic atrial fibrillation (AF). Since recent clinical studies have shown that non-fractionated electrograms were recorded during sinus rhythm at chronic AF CFAE sites and that blocker of the fast component of the delayed rectifier K current (IKr) diminished CFAE regions, whether the CFAE mechanisms are functional or structurally-based remains a topic of debate.
Hypothesis: Functional properties of CFAE during chronic AF can be explained by fibroblast proliferation as part of structural remodeling.
Methods: To address this issue, we investigated the electrophysiological mechanisms of CFAE using in silico model of human chronic AF under heart failure, based on the Fibroblast-CFAE hypothesis (Circ Res 2012) stating that fibroblast proliferation leads to the formation of CFAEs during chronic AF.
Results: (1) CFAEs were recorded in fibroblast proliferation area (Fb-Area) where spiral wave breakup was observed, because the small excitable gap (resulting from the short diastolic intervals) decreased myocardial excitability (Figure, left panel). (2) Non-fractionated electrograms were recorded in the same area during pacing because the larger excitable gap (longer diastolic intervals) recovered myocardial excitability, preventing wave breakup (Figure, right panel). (3) In case of IKr block by 50%, spiral wave breakup was suppressed and the excitation intervals during AF were prolonged, resulting in the decrease in CFAE complexity. These simulation results are consistent with clinical studies in patients with chronic AF.
Conclusion: Since fibroblast proliferation alters electrotonically the electrophysiological properties of the atrial myocardium via myocyte-fibroblast coupling, structural remodeling in the atrial myocardium cannot be excluded even if CFAEs exhibit functional features.
- © 2012 by American Heart Association, Inc.