Patent ID: 7558623

Claim:
A system for detecting a cardiac event in a human patient, the system including: at least two electrodes implanted in the patient for obtaining the electrical signal from the patient's heart, the electrical signal being an electrogram; an implantable device having alerting means, the implantable device designed to process the electrogram at a first time period, thereby obtaining a reference value of a heart signal parameter, and to store the reference value of the heart signal parameter, and to detect a cardiac event by processing the electrogram at a second time that is at least twelve hours after the first time, the implantable device designed to categorize detected cardiac events into at least two different levels of severity, wherein a cardiac event associated with a relatively lower level of severity is based on the value of the heart signal parameter resulting from an elevated heart rate during a second time period as compared to the reference value of the heart signal parameter when measured at the first time period.