A medical device system comprising: sensing circuitry configured to generate one or more physiological signals of a patient; and processing circuitry that, for each of a plurality of periods, is configured to: determine a respective value for each of a plurality of patient parameters, wherein, for one or more of the plurality of patient parameters, the respective values are determined based on the one or more physiological signals generated during the period; for each of the plurality of patient parameters, determine a difference metric for a current period for each of the plurality of periods based on a value of the patient parameter determined for the current period and a value of the patient parameter determined for an immediately preceding period of the plurality periods; determine a score for the current period based on a sum of the difference metrics for the current period for the one or more of the plurality of patient parameters; determine a threshold for the current period based on scores determined for N periods of the plurality of periods that precede the current period, wherein N is an integer constant; compare the score for the current period to the threshold for the current period; and determine whether to generate an alert indicating that an acute cardiac event of the patient is predicted based on the comparison. sensing circuitry configured to generate one or more physiological signals of a patient; and processing circuitry that, for each of a plurality of periods, is configured to: determine a respective value for each of a plurality of patient parameters, wherein, for one or more of the plurality of patient parameters, the respective values are determined based on the one or more physiological signals generated during the period; for each of the plurality of patient parameters, determine a difference metric for a current period for each of the plurality of periods based on a value of the patient parameter determined for the current period and a value of the patient parameter determined for an immediately preceding period of the plurality periods; determine a score for the current period based on a sum of the difference metrics for the current period for the one or more of the plurality of patient parameters; determine a threshold for the current period based on scores determined for N periods of the plurality of periods that precede the current period, wherein N is an integer constant; compare the score for the current period to the threshold for the current period; and determine whether to generate an alert indicating that an acute cardiac event of the patient is predicted based on the comparison. determine a respective value for each of a plurality of patient parameters, wherein, for one or more of the plurality of patient parameters, the respective values are determined based on the one or more physiological signals generated during the period; for each of the plurality of patient parameters, determine a difference metric for a current period for each of the plurality of periods based on a value of the patient parameter determined for the current period and a value of the patient parameter determined for an immediately preceding period of the plurality periods; determine a score for the current period based on a sum of the difference metrics for the current period for the one or more of the plurality of patient parameters; determine a threshold for the current period based on scores determined for N periods of the plurality of periods that precede the current period, wherein N is an integer constant; compare the score for the current period to the threshold for the current period; and determine whether to generate an alert indicating that an acute cardiac event of the patient is predicted based on the comparison.