  One of the challenges in the development of patient-specific models of
cardiac arrhythmias for clinical applications has been accounting for
myocardial fiber organization. The fiber varies significantly from heart to
heart, but cannot be directly measured in live tissue. The goal of this paper
is to evaluate in-silico the accuracy of left atrium activation maps produced
by a fiber-independent (isotropic) model with tuned diffusion coefficients,
compares to a model incorporating myocardial fibers with the same geometry. For
this study we utilize publicly available DT-MRI data from 7 ex-vivo hearts. The
comparison is carried out in 51 cases of focal and rotor arrhythmias located in
different regions of the atria. On average, the local activation time accuracy
is 96% for focal and 93% for rotor arrhythmias. Given its reasonably good
performance and the availability of readily accessible data for model tuning in
cardiac ablation procedures, the fiber-independent model could be a promising
tool for clinical applications.
