A system and method detects and terminates a repetitive nonreentrant ventriculo-atrial synchronous (RNRVAS) rhythm. The system and method is particularly adapted for use in an implantable cardiac stimulation device that includes a pulse generator that delivers atrial and ventricular pacing stimulation pulses and implements an atrial escape interval and a VA delay interval. This system includes a sensing circuit that senses cardiac activity of a heart and a detector that is responsive to the sensing circuit that determines if an RNRVAS rhythm is present. If an RNRVAS rhythm is present, a therapy control circuit causes the pulse generator to deliver a secondary atrial pacing pulse following a primary atrial pacing pulse delivered at the end of an atrial escape interval. The therapy control circuit may additionally cause the pulse generator to deliver a tertiary atrial pacing pulse following the next ventricular pacing pulse to prevent the occurrence of a retrograde P wave.