Abstract: A method and system for testing the integrity of a high voltage output stage and high voltage leads of an implantable cardioverter/defibrillator. The method and system comprises charging one or more high voltage capacitors associated with the high voltage output stage to a predetermined relatively low voltage on the order of 10-20 volts, discharging the high voltage capacitors synchronous with a sensed cardiac event for a predetermined time period, measuring a residual voltage on the high voltage capacitors, and then comparing the residual voltage to a reference voltage to assess the integrity of the output stage and high voltage leads.