1. A method of automatically determining which of a plurality of possible types of cardiac interventions should be performed in treatment of a patient, the method comprising: storing first prior information representative of types of prior cardiac interventions performed on the patient; storing second prior information representative of the patient's reactions to the prior cardiac interventions; wherein the first and second prior information are other than heart rhythms or ECG waveforms; and processing the first and second prior information using a hidden Markov model to determine which of a plurality of possible further cardiac interventions should be performed.