Cell therapy and tissue engineering applied to cardiac tissue underlie the use of cultured cells. These cells show intrinsic variability in their contractile or electrical properties. An interesting innovative application of tissue engineering is the biopacemaker patch consisting of autonomous electrical cardiac cells that could ultimately serve as a replacement for electronic pacemakers. Experiments show that initial seeding of cells is composed of mainly two populations: electrically spontaneous cells and excitable but non-autonomous cells. Random initial deposition followed by an unknown state-dependent cell division process creates a spatially heterogeneous monolayer with intrinsic rate of electrical activity. A mathematical model of stochastic dispersion of autonomous cells was studied to investigate the effects of varying spatial patterns of cell and its influence on inter-sample rate. As a first step, cells are modeled with modified Fitzhugh-Nagumo models and deposited via a stochastic algorithm to form a completely full square monolayer. As expected, higher density of spontaneous cell increases the rate of activity of the monolayer and faster changes with increasing density are found for cases with increased growth of existing clusters. Interestingly, inter-sample variability is greater for distribution showing lower fractal dimension for identical density of spontaneous cell. These results confirm the need for a better understanding of cell characteristics and spatial patterning within the cell monolayer to optimize the biopacemaker function.