Depolarization waves are described by the basic model for the cardiac reaction-diffusion system: The bidomain equations for electrical potentials in and between cells and the spread of the depolarization waves. Our goal is to develop, to analyze, and to numerically realize a fully coupled model for the cardiac electromechanical system. This includes the dynamics of depolarization waves and their initiation by pace-and-drive mechanisms allowing for a qualitatively correct prediction of depolarization wave patterns on the time-dependent heart geometry.