A mobile plethysmographic device for detecting a Peripheral Artery Disease (“PAD”) event or other arrhythmia event is disclosed herein. The mobile plethysmographic device generates a pleth waveform, which is automatically screened by algorithms that measure the waveform to correlate, detect and store aberrations related to heart anomalies. A peripheral artery disease event for a patient is determined based on a quantative measure of blood flow in the extremities based on the differential in amplitude in the pleth signal between the arm and the two lower extremities. The changes in amplitude from the arm and one or both lower extremities can indicate PAD.