Automatic switching between the AAI and the DDD algorithm can prevent repetitive non-reentrant ventriculoatrial synchrony

A 67-year-old man with non-obstructive hypertrophic cardiomyopathy had received an implantable cardioverter-defibrillator (ICD) for an unstable, sustained ventricular tachycardia (VT) induced by programmed stimulation during an electrophysiological study 5 years earlier. An intracardiac electrogram recorded by the ICD revealed repetitive, non-reentrant ventriculoatrial synchrony (RNRVAS) associated with hypotension. Electrophysiologic and hemodynamic studies indicated that RNRVAS was induced and reproducibly termed by a single ventricular extrastimulus from the right ventricular apex. Following attainment of the elective replacement indicator, we replaced the ICD with another having managed ventricular pacing, which automatically switched AAI and DDD, thereby avoiding unnecessary ventricular pacing. Thus far, the patient has not experienced further RNRVAS. Thus, we believe that automatic switching between AAI and DDD can prevent RNRVAS.