Patent ID: 7957803

Claim:
An implantable cardiac device, comprising: a plurality of implantable cardiac electrodes configured to be electrically coupled to a heart; sensing circuitry configured to sense cardiac signals; a processor configured to control delivery of a first pacing pulse to an atrium during a first cardiac cycle, sense for an atrial evoked response following delivery of and associated with the first atrial pacing pulse, sense for an intrinsic activation of a ventricle during the first cardiac cycle, deliver a pacing pulse to the ventricle if the intrinsic ventricular activation is not sensed during the first cardiac cycle, sense in the atrium for a retrograde P-wave, the retrograde P-wave responsive to the ventricular pacing pulse or the intrinsic ventricular activation, classify the cardiac response to the first atrial pacing pulse as a non-captured response if the retrograde P-wave is detected and the atrial evoked response is not detected, classify the cardiac response to the first atrial pacing pulse as a captured response if the atrial evoked response is detected, and, deliver, during a second cardiac cycle immediately following the first cardiac cycle, a second atrial pacing pulse to the atrium, the second atrial pacing pulse having a scheduled delivery time, but the second atrial pacing pulse being delivered at a time that is delayed relative to the scheduled delivery time if the cardiac response of the first atrial pacing pulse is classified as a non-captured response and if a time period between the detected retrograde P-wave and the scheduled delivery time is no greater than an atrial effective refractory period (AERP).