Patent ID: 7062328

Claim:
In an implantable cardiac stimulation device, a method comprising: detecting intrinsic atrial events based on an initial atrial sensitivity level; selectively delivering atrial pacing pulses to at least one atrium and monitoring for loss of capture of the atrial pacing pulses; increasing the atrial sensitivity level upon detecting a predetermined number of losses of capture and monitoring for lower-amplitude atrial events; if lower amplitude atrial events are detected, determining whether the lower amplitude atrial events are true intrinsic atrial events; if lower-amplitude atrial events are not detected, resetting the atrial sensitivity to the initial value; and controlling selected functions of the device based on any true intrinsic atrial events; wherein the device is capable of automatically switching between a tracking mode and a non-racking mode and wherein controlling selected functions of the device further comprises: determining a filtered atrial rate interval (FARI value) based only on intrinsic atrial events; and controlling mode selection based on the FARI value.