Patent ID: 8315699

Claim:
A method for monitoring a patient's heart rhythm, the method comprising: sensing cardiac events using a first cardiac electrode pair; detecting a sudden change in the heart rhythm in response to the sensed cardiac events; and detecting a concerning cardiac rhythm in response to detecting the sudden change, wherein detecting the sudden change comprises: measuring a plurality of event intervals between the sensed cardiac events; determining a variability of intervals between the sensed cardiac events; in response to the determined variability of intervals, switching between a low variability mode of operation for detecting the sudden change and a high variability mode of operation for detecting the sudden change; during the low variability mode of operation, detecting the sudden change as a sudden increase in the rate of the cardiac events in response to the plurality of cardiac event intervals; and during the high variability mode of operation, detecting the sudden change as a sudden decrease in the variability of the plurality of cardiac event intervals.