A method of mapping cardiac electrical activity includes the acquisition of electrophysiological signals and using signal processing hardware to process such signals to identify lateness attributes thereof. If the lateness attribute exceeds a lateness threshold, then the corresponding point on the patient's heart can be designated as a therapy (e.g., ablation) target. It is also contemplated to use an upper bound on the lateness threshold, such that the corresponding point on the patient's heart is only designated as a therapy target if the lateness attribute both exceeds the lateness threshold and does not exceed the lateness bound. Both late activation (&ldquo；Late-A&rdquo；) and late potential (&ldquo；Late-P&rdquo；) attributes are contemplated.
