Atrial tachycardia misinterpreted as ventricular high-rate event in a patient with the sick sinus disease and a DDD pacemaker.

The device misinterpreted atrial high-rate episode (AHRE) as ventricular high-rate episode (VHRE), since consecutive atrial beats fell in the postventricular atrial blanking (PVAB) period. This resulted in the failure of auto mode switch (AMS). This was corrected by decreasing the PVAB and the patient was asymptomatic on follow-up.