A cardiac monitoring device for determining the occurrence of a sick sinus syndrome condition of a patient that includes a plurality of electrodes to sense a cardiac signal, a sensing module electrically coupled to the plurality of electrodes having circuitry positioned therein to receive the sensed cardiac signal, and a processor coupled to the sensing module and configured to determine an RR interval variability during an RR interval variability session in response to the sensed cardiac signal, determine whether a P-wave occurs during the RR interval variability session, determine whether a sick sinus indicator is satisfied in response to a P-wave occurring, increment a sick sinus count in response to the sick sinus indicator being satisfied, determine whether a sick sinus burden is satisfied in response to the sick sinus count being incremented, and determine the occurrence of sick sinus syndrome in response to the sick sinus burden being satisfied.
