The invention concerns a data processing apparatus (12) for processing T-wave information (TI) or ST-segment (ST) 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, characterised in that the data processing apparatus (12) is configured to derive a T-wave deviation value (DV, NDV, 2DV, N2D) from a difference of at least two T-wave parameters (P) or ST-segment parameters (P), wherein each of the two parameters (P) belongs to another T-wave (T) or ST-segment (ST) 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.
