A device, system and related methods for monitoring a mammal with heart failure, kidney disease or both, to make predictions about the likelihood of a life threatening ventricular arrhythmia. The device, system and related methods can have one or more sensors in electronic communication with a processor, the sensors determining one or more physiological parameters of a patient, and communicating the physiological parameter to the processor, and the processors using an algorithm to determine the probability of a ventricular arrhythmia based on the physiological parameters.