1. A medical image diagnosis assisting apparatus, comprising: a cardiac function analyzer configured to calculate, with one or more of first three-dimensional medical images representing a heart as input, a cardiac function evaluation value representing a cardiac function with respect to each of predetermined portions of the heart; a myocardial infarction analyzer configured to calculate, with one or more second three-dimensional medical images representing the heart as input, a myocardial infarction rate representing a degree of myocardial infarction with respect to each of predetermined portions of the heart; and a superimposed image generator configured to output a superimposed image representing the cardiac function evaluation value and the myocardial infarction rate in a superimposing manner such that they are distinguishable from each other in a coordinate system capable of representing each position of the heart in the three-dimensional medical image; wherein: the cardiac function analyzer is further configured to calculate, with the one or more of first three-dimensional medical images representing the heart in one or more of predetermined cardiac phases respectively, a cardiac function evaluation value for myocardial wall motion; the myocardial infarction analyzer is further configured to calculate a myocardial infarction rate from the one or more second three-dimensional medical images representing a delayed enhancement phase of a heart obtained by imaging a subject with an MRI system after predetermined time from the time of administration of a predetermined contrast agent to the subject; and wherein: the apparatus further comprises a correspondence relationship determinator configured to determine a correspondence relationship of anatomical positions of the heart in the first and second three-dimensional medical images; the superimposed image is an image in which the cardiac function evaluation values and the myocardial infarction rate at corresponding anatomical positions are represented at the same position in the coordinate system based on the correspondence relationship of the anatomical positions; the medical image diagnosis assisting apparatus is configured to generate and display a topography map; and the medical image diagnosis assisting apparatus is configured to display an anatomy of the coronary artery with the cardiac function evaluation values and infraction rates in a superimposing manner; wherein: the apparatus comprises a coronary artery extractor contfigured to extract a coronary artery region from a three-dimensional medical image representing the heart; and wherein the superimposed image output generator outputs a superimposed image further representing the extracted coronary artery region in a superimposing manner in the coordinate system, said coronary artery region being distinguishable in the superimposed image.