The invention concerns a data processing apparatus for processing T-wave information or ST-segment information from an electrical signal from a myocardium of a heart of a human or animal, for an assessment of a condition of at least a part of the myocardium or the whole myocardium, characterized in that the data processing apparatus is configured to derive a T-wave deviation value from a difference of at least two T-wave parameters or ST-segment parameters, wherein each of the two parameters belongs to another T-wave or ST-segment from the same heart. Further, an assessment apparatus for assessing the condition of at least a part of a myocardium of a heart of an individual human or animal, a method for providing data for an assessment of a condition of at least a part of a myocardium of a heart of a human or an animal, wherein the method includes processing T-wave information from an electrical signal from at least a part of a myocardium and a diagnosis method for diagnosing a condition or a disease of a heart are proposed. Further, a method for data processing, a method for assessing a condition or a disease of the heart and a diagnosis method are proposed.
