In an example, a cardiac rhythm management system includes an implantable physiological data monitor, a processor, a memory, and a display. The implantable physiological data monitor can be configured to monitor a plurality of cardiac responses. The processor can be configured to classify the cardiac response into one of at least three classes including pace-dominant, fusion, and pseudo-fusion. The processor can also be configured to calculate statistical information regarding the classified cardiac responses. In this example, the pace-dominant, fusion, and pseudo-fusion classes correspond to a cardiac response resulting from a corresponding electrostimulation. The memory is configured to store the classified cardiac responses and calculated statistical information for future use by the processor or for display. The display is configured to display the statistical information stored in the memory for diagnostic and device programming purposes.