US Patent 10335047 Automatic heart rate diagnostics

In some examples, processing circuitry of a medical device system determines, for each of a plurality of periods, a plurality of heart rates of a patient based on a cardiac electrogram signal, and identifies a first subset of the plurality of heart rates as nighttime heart rates and a second subset of the plurality of heart rates as resting heart rates. The processing circuitry determines a representative nighttime heart rate based on the first subset of the plurality of heart rates, determines a representative resting heart rate based on the second subset of the plurality of heart rates, and determines a nocturnal dip base on the representative nighttime heart rate and the representative resting heart rate. The processing circuitry compares at least one of the representative nighttime heart rate, the representative resting heart rate, and the nocturnal dip in heart rate to a respective threshold value, and determines whether to generate an alert indicating a change in the cardiac function of the patient based on the comparison.