  Sustained spiral waves, also known as rotors, are pivotal mechanisms in
persistent atrial fibrillation (AF). Stochasticity is inevitable in nonlinear
biological systems such as the heart; however, it is unclear how noise affects
the instability of spiral waves in human AF. This study presents a stochastic
two-dimensional mathematical model of human AF and explores how Gaussian white
noise affects the instability of spiral waves. In homogeneous tissue models,
Gaussian white noise may lead to spiral-wave meandering and wavefront break-up.
As the noise intensity increases, the spatial dispersion of phase singularity
(PS) points increases. This finding indicates the potential AF-protective
effects of cardiac system stochasticity by destabilizing the rotors. By
contrast, Gaussian white noise is unlikely to affect the spiral-wave
instability in the presence of localized scar or fibrosis regions. The PS
points are located at the boundary or inside the scar/fibrosis regions.
Localized scar or fibrosis may play a pivotal role in stabilizing spiral waves
regardless of the presence of noise. This study suggests that fibrosis and
scars are essential for stabilizing the rotors in stochastic mathematical
models of AF. Further patient-derived realistic modeling studies are required
to confirm the role of scar/fibrosis in AF pathophysiology.

Biological Physics;Pattern Formation and Solitons;Tissues and Organs