In this paper, we study the stability result for the conductivities diffusion coefficients to a strongly reaction-diffusion system modeling electrical activity in the heart. To study the problem, we establish a Carleman estimate for our system. The proof is based on the combination of a Carleman estimate and certain weight energy estimates for parabolic systems.where f and g are stimulation currents applied to Ω. We complete this model with Dirichlet boundary conditions for the intra-and extracellular electric potentials