The management of patients with pacemakers who experience episodes of atrial arrhythmia is complex due to the various known mechanisms that trigger atrial arrhythmias and the risk of ventricular pacing runaway upon detection of a rapid atrial rhythm.

The device can be programmed to respond to atrial arrhythmia by switching to an asynchronous mode to avoid high-frequency ventricular pacing that could compromise hemodynamic stability. Mode switching refers to the pacemaker’s ability to automatically switch from an atrial-led mode (DDD or VDD) to a non-atrial-led mode (DDI or VDI). The ventricular pacing rate gradually decreases from the maximum synchronous rate to the slave rate or base rate. This prevents a sudden drop in the ventricular rate. When the atrial tachyarrhythmia ends, mode switching returns to the programmed synchronous pacing mode.

Mode switching is programmed by default and must not be deprogrammed even if the patient has no known history of atrial arrhythmia. In this patient, the absence of a drop in rate is associated with prolonged rapid ventricular pacing at the maximum tracking rate. The combination of loss of atrial systole and runaway ventricular pacing is responsible for the observed signs of cardiac decompensation.

In this patient, it is necessary to program the retraction to prevent ventricular synchronization with rapid atrial activity.