Patent ID: 8145307

Claim:
A method for detecting a cardiac event in a patient, comprising: determining an activity level count from an activity sensor signal for each of a plurality of time segments; storing an activity level count for each of the plurality of time segments in a histogram; accumulating the stored activity level counts to determine a percentage of time segments having an activity level count above a given activity level count; establishing an activity level count threshold in response to the accumulated activity level counts; sensing a cardiac signal from a plurality of electrodes for each of the plurality of time segments; classifying the cardiac signal for each of the plurality of time segments as one of a treatable segment and a non-treatable segment; comparing a stored activity level for a given one of the plurality of time segments to the activity level count threshold in response to classifying a treatable segment; reclassifying the treatable segment as a non-treatable segment if the stored activity level for the given one of the plurality of time segments is greater than the activity level count threshold; and detecting the cardiac event in response to a treatable segment not being reclassified.