A system and method for facilitating a cardiac rhythm disorder diagnosis with the aid of a digital computer is provided. Cutaneous action potentials of a patient are recorded over a set period of time as ECG data and a difference between recording times of successive pairs of R-wave peaks are recorded as R-R intervals. A heart rate is associated with each time difference. An R-R interval plot of the ECG data is generated. A presence of a cardiac event is displayed by presenting a presence of sinus tachycardia or a presence of bradycardia via the R-R interval plot.