1. In an implantable medical device for implant within a patient, the device having a plurality of sensors and a control unit for processing signals from the sensors, a method performed by the control unit comprising: receiving signals from the sensors representative of physiological parameters of the patient; determining a value representative of a risk of mortality for the patient to congestive heart failure based on the signals; and comparing the value representative of risk of mortality with a threshold value and generating a warning signal if the value representative of risk of mortality exceeds the threshold value.