a mobile plethysmographic device for detecting a premature atrial contraction 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 premature atrial contraction event for a patient is determined based on an identification of a time interval of the pleth waveform that is below the threshold minimum time interval followed immediately by a time interval that is above the threshold maximum time interval .