An example system and method of processing cardiac activation information are disclosed. The method includes accessing a first cardiac signal and a second cardiac signal obtained from a patient. The first cardiac signal and the second cardiac signal are processed to determine whether there is a point of change in the first cardiac signal at which a derivative of the first cardiac signal diverges 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 a cardiac activation if the point of change is in the first cardiac signal.