A medical device includes pacing circuitry configured to deliver during a cardiac cycle a first pacing pulse to a first site using a first electrode as a cathode electrode for the first pacing pulse and to deliver a second pacing pulse to a second site using a second electrode as a cathode electrode for the second pacing pulse. Sensing circuitry is configured to generate a differential signal between cardiac electrical activity sensed at the first electrode and cardiac electrical activity sensed at the second electrode. Capture circuitry discriminates between single site capture and multi-site capture based on the differential signal.
