on cardiac re-entry dynamics, although difficult to demonstrate in experiment, is well appreciated [@Bishop-etal-2010; @Bishop-etal-2011; @Bishop-Plank-2012; @Fukumoto-etal-2016], and has been studied in simplified mathematical and computer models [@Fenton-Karma-1998; @Pertsov-etal-PRL2000; @Wellner-etal-PNAS2002; @RodriguezEasonTrayanova-2006; @Dierckx-etal-PRE2013]. The [BeatBox]{} [@bbx-2017-PONE] High Performance Computing (HPC) cardiac electrophysiology computer simulation environment allows direct incorporation of the high resolution DT-MRI heart anatomy data sets into the biophysically and anatomically realistic computer simulations. In the [BeatBox]{} *in-silico* model, the anisotropy of the tissue is switched “on” and “off” to allow for comparison between the anatomically realistic isotropic and anisotropic conduction, in order to see the specific pure anatomy effects, as well as the interplay between the anisotropy and anatomy of an individual heart. In this paper, we present the DT-MRI based anatomy and myofiber structure realistic computer simulation study of cardiac re-entry dynamics in the *in-silico* model of the human foetal heart [@Pervolaraki-etal-2013]. We demonstrate that, in a 2D slice of the heart, the realistic fiber anisotropy of the tissue changes cardiac re-entry dynamics from pinned into fast anatomical re-entry. In the full 3D DT-MRI based model, depending on the initial location of the re-entry, the isotropic geometry of the heart might sustain a perpetual re-entry even with a 