Methods and devices for classifying a
cardiac response to pacing involve establishing a retriggerable
cardiac response classification window. A first
cardiac response classification window is established subsequent to delivery of a pacing pulse. A cardiac
signal following the pacing stimulation is sensed in the first classification window. A second cardiac response classification may be triggered if a trigger characteristic is detected in the first classification window. The cardiac
signal is sensed in the second classification window if the second classification window is established. The cardiac response to the pacing stimulation is determined based on characteristics of the cardiac
signal. The cardiac response may be determined to be one of a captured response, a non-captured response; a non-captured response added to an intrinsic beat, and a fusion / pseudofusion beat, for example.