1. A system for visualizing a cardiac parameter at a plurality of positions in a myocardium and at a plurality of stress levels, the system comprising: a memory unit which receives and stores stress level cardiac functional data, the stress level cardiac functional data including cylindrical coordinates of positions on an outer surface and on an inner surface of a wall of the myocardium at a plurality of phases of a cardiac cycle and at a plurality of stress levels; a determination unit for determining a value of the cardiac parameter at a position from the plurality of positions in the myocardium and at a stress level from the plurality of stress levels on the basis of stress level cardiac functional data; and a visualization unit for visualizing the determined value of the cardiac parameter by displaying a point in a viewing plane, where in a polar coordinate system in the viewing plane; a radial coordinate of the point visualizes the determined value of the cardiac parameter; and an angular coordinate of the point visualizes an angular coordinate of the position in the myocardium in a cylindrical coordinate system.