We provide an analysis of the bidomain theory in relation to anterior subendocardial ischemia. Using the static bidomain model, this analysis explains why simulations often do not produce ST depression when the ischemia is introduced into an anisotropic model. More precisely, if the ischemic border zone is represented as a smooth surface, then almost right angles between the normal vector of the border and the tangential plane of the fibers will lead to cancelling effects. The simulated transmembrane current flux, entering the ischemic region, will thus be underestimated, and the expected ST depression in chest leads may not occur.