Patent ID: 8452405

Claim:
A method of operating an implantable cardiac rhythm device to deliver pacing to an atrium, the method, comprising: delivering atrial pacing during an atrial capture threshold test; using a post ventricular refractory period (PVARP) having a first PVARP duration during cardiac cycles of the atrial pacing in which an atrial pace captures the atrium; using an A-A interval having a first A-A interval duration between cardiac cycles of the atrial pacing in which the atrial pace captures the atrium; and using a PVARP having a second PVARP duration and using an A-A interval having a second A-A interval duration during cardiac cycles of the atrial pacing in which the atrial pace does not capture the atrium, wherein the second PVARP duration is greater than the first PVARP duration and the second A-A interval duration is greater than the first A-A interval duration and is extended from an atrial depolarization sensed during the PVARP having the second PVARP duration.