Atrial tachyarrhythmia detection using selected atrial intervals

A cardiac device, comprising:

• sensing circuitry configured to sense atrial depolarizations;
• a therapy controller configured to control cardiac pacing therapy;
• and
• an atrial tachyarrhythmia detector configured to
• detect A-A intervals between consecutive atrial depolarizations,
• identify A-A intervals in a sequence
• select A-A intervals of the sequence for use in atrial tachyarrhythmia detection based on at least one of:
• information about a first of a pair of sequential A-A intervals relative to a second of the pair of sequential A-A intervals, wherein the information comprises at least one of
• a comparison of a duration of a first A-A interval to a duration of a second A-A interval, and
• odd/even sequence information, and
• information about events occurring between consecutively sensed atrial depolarizations of the A-A intervals,
• operate at least one counter using the selected A-A intervals, and
• detect tachyarrhythmia based on an output of the counter.