47 years old man, implanted with a triple chamber defibrillator Viva XT CRT-D for dilated cardiomyopathy with left bundle branch block; 3 months – routine – follow-up after implantation (DDD 70 bpm) ;
Tracing
In the absence of manifest sinus node dysfunction, it is preferable to promote spontaneous atrial activity by programing a relatively low minimal HR. In this patient, programming the minimal HR at 70 bpm induced a competition and alternation between the spontaneous atrial rhythm and the atrial pacing. Slowing the minimum frequency yielded a permanent atrial sensing at rest as during exercise which allows 1) to limit energy consumption and save battery 2) maintain a physiological atrial activation and reduce the atrial activation time. However, the effect on the potential occurrence of an atrial arrhythmia remains more controversial.
