Electrogram fractionation caused by microfibrosis: insights from a microstructure model

Fractionated electrograms have long been associated with non-uniform propagation in the atria, owing to a heterogeneous substrate marked by fibrosis. It is not known, however, whether the features of the electrograms can be used to quantify the degree of fibrosis in the heart. A computer model of a monolayer of cells was developed to investigate how progression of microfibrosis impacts electrogram morphology and the degree of fractionation. The analysis of unipolar electrograms simulated in the model revealed that more pronounced microfibrosis was associated with slow conduction and electrogram waveforms featuring a higher degree of fractionation and a larger spatial variability in morphology. This modeling framework forms a basis to better understand the genesis of fractionated electrograms and for developing a strategy to use the electrogram features to quantify fibrosis in patients with atrial fibrillation, possibly impacting the target sites for catheter ablation.