Efficacy of the DDD+ Overdrive Algorithm for the Suppression of Atrial Tachyarrhythmias

Atrial fibrillation (AF) persists as the most challenging arrhythmia in clinical practice, and it currently affects an estimated 400 million people worldwide. We view AF as the most common sustained supraventricular tachyarrhythmia, for it is associated with extensive morbidity and mortality [1]. According to some studies, AF is responsible for numerous hospitalizations, which result in significant increases in the cost of healthcare [2]. Permanent pacing has been regarded as a safe option in the prevention of atrial tachyarrhythmias (AT), especially AF, and it has been the focus of extensive investigations. Some studies have demonstrated that atrial pacing (AAI or DDD) is clearly associated with a lower incidence of paroxysmal and permanent AF [3-6] when compared with single-chamber ventricular pacing. Recently, new targeted pacing algorithms have been integrated into dual-chamber pacemakers for the prevention or even the elimination of ATs, adding an innovative perspective in the management of these arrhythmias. Among them is overdrive pacing, which is based on preventive atrial overpacing slightly above the sinus rate. It provides additional benefits by reducing the dispersion of refractoriness [7,8], the delay in interatrial conduction, and the frequency of ectopic beats [9,10]. The DDD+ mode of the Philos DR system (Biotronik, Germany) is an algorithm based on a normal, P-wavesynchronized, atrioventricular pacing (DDD) mode. Moreover, the overdrive pacing mode (DDD+) increases the basic rate after every valid atrial sensed event. The algorithm reacts to an intrinsic atrial beat classified as sinus rhythm by the device with a pro-