A system for heart performance characterization uses an interface to receive waveform signal data representing electrical activity of a patient heart over at least one heart beat cycle. The signal processor uses a signal peak and amplitude detector for, identifying a first signal portion of a first heart cycle of the signal data, identifying multiple different amplitude levels within the first signal portion, determining a first area under the waveform in the first signal portion corresponding to at least one particular amplitude level and deriving a parameter in response to the determined first area. The output processor generates an alert message if at least one of, (a) the derived parameter and (b) a difference between the derived parameter and a corresponding derived parameter for a different heart cycle for the same patient, exceeds a predetermined threshold value.