An arrangement (100) for electromagnetic radiation based non-invasive monitoring or assessment of a performance of an anatomic object, such as a heart (101) during an operation, such as an open cardiac surgery of a subject comprises at least one imaging device (102) or imaging input device for obtaining at least two or more images of at least one surface point (113) on a surface of the anatomic object over at least one fraction of a characteristic movement cycle from the surface of the anatomic object. In addition the arrangement comprises an output for a display device (106) or said display device (106), and a control unit (104) for determining deformation based on movements of said at least one surface point (113) over said at least one fraction of the cycle between said at least two or more images of the surface of the heart in function of time. Further changes in said deformation is determined or determined deformation is compared to reference deformation values to find any deviation in said performance or state of the deformation determined. Additionally control data is provided for controlling the display device (106) to display the changes in said deformation or said deviation or state of the deformation determined in function of time.