A Grid Search of Fibrosis Thresholds for Uncertainty Quantification in Atrial Flutter Simulations.

Atypical atrial flutter (AAF) is a cardiac arrhythmia commonly developed following catheter ablation for atrial fibrillation. Patient-specific computational simulations of propagation have shown promise in prospectively predicting AAF reentrant circuits and providing useful insight to guide successful ablation procedures. These patient-specific models require a large number of inputs, each with an unknown amount of uncertainty. Uncertainty quantification (UQ) is a technique to assess how variability in a set of input parameters can affect the output of a model. However, modern UQ techniques, such as polynomial chaos expansion, require a well-defined output to map to the inputs. In this study, we aimed to explore the sensitivity of simulated reentry to the selection of fibrosis threshold in patient-specific AAF models. We utilized the image intensity ratio (IIR) method to set the fibrosis threshold in the LGE-MRI from a single patient with prior ablation. We found that the majority of changes to the duration of reentry occurred within an IIR range of 1.01 to 1.39, and that there was a large amount of variability in the resulting arrhythmia. This study serves as a starting point for future UQ studies to investigate the nonlinear relationship between fibrosis threshold and the resulting arrhythmia in AAF models.