An example system and method of reconstructing cardiac activation information are disclosed. A first cardiac signal and a second cardiac signal are processed via a computing device to determine whether there is a point of change in a derivative of the first cardiac signal with respect to a derivative of the second cardiac signal above a threshold. An activation onset time is assigned in the first cardiac signal at the point of change to define cardiac activation indicating a beat in the first cardiac signal if it is determined that the point of change is above the threshold.
