Optimization of evoked response detection in an automatic capture detection system employed by an implantable cardiac stimulation device is presented. Patient state information is used to determine the appropriate settings of variables that are associated with the evoked response signal detection algorithm. The variables used by the evoked response signal detection algorithm are first established for the patient in a variety of positions. During operation of the implantable cardiac stimulation device, the patient state is monitored and the variables used by the evoked response signal detection algorithm are adjusted accordingly.