A computer readable program storage unit encoded with instructions that, when executed by a computer of a medical device, perform a method for indicating via a communication unit an occurrence of a state change, wherein the method performed by the instructions comprises the steps of obtaining, by using sensors coupled via sensor leads to the medical device, data relating to at least a portion of a heart beat complex from a patient comparing the at least portion of the heart beat complex with a corresponding portion of a first reference heart beat complex template of the patient and indicating the occurrence of the state change based upon a determination that the heart beat complex fails to match at least one characteristic of the first reference heart beat complex template.
