A method includes receiving a cardiac signal that is sensed by electrodes at a location in a heart of a patient, the cardiac signal including signal components evoked by respective activations. The signal components in the cardiac signal are found and annotated. Respective time differences are calculated between the annotations and the corresponding activations. Based on the time differences, one or more cardiac tissue locations are identified, that demonstrate progressively slowing activation (PSA). An EP map of at least a portion of the heart is presented to a user, including providing a graphical indication of the one or more tissue locations that demonstrate the PSA.