Methods and systems involve the formation of a classification interval used for sensing a cardiac signal following a pacing pulse to determine a cardiac response to pacing. One or more cardiac signals associated with a type of cardiac pacing response are sensed. The timing of at least one feature of the cardiac signal may be used to define an initial cardiac response classification interval. The classification interval is adapted based on the variability of the timing of the feature. The classification interval may be adapted using a predetermined number of additional cardiac signals or until a predetermined stability criterion is achieved.