Fibrosis Reduces the Coincidence of Repetitive Activation Patterns between the Coronary Sinus and Atrial Regions in Simulated Atrial Fibrillation

Repetitive Atrial Activation Patterns (RAAPs) detected in the coronary sinus (CS) during atrial fibrillation (AF) may represent a reference to construct composite maps of coincident local RAAPs elsewhere in the atria, potentially improving the identification of AF drivers. RAAP coincidence may however depend on AF complexity and may be affected by structural remodeling. Using computer simulations, we investigated coincidence and coupling of RAAPs in the CS and other regions in the atria, in the absence and presence of fibrosis. In our models, the CS displayed highly repetitive behavior unaffected by fibrosis. RAAP coincidence and coupling of other regions in the atria with the CS was high in the absence of fibrosis, but significantly decreased in the presence of fibrosis, most notably in the left atrium. In coincident RAAPs in the CS and atrial regions, quantification of the degree of RAAP coupling is required to provide further confirmation of the validity of employing CS electrograms as a reference for composite RAAPs maps.