Programming a fixed long atrioventricular delay is not effective in preventing ventricular pacing in patients with sick sinus syndrome

Aim Most patients with sick sinus syndrome (SSS) and normal atrioventricular (AV) conduction receive dual chamber (DDDR) pacemakers. Programming a long AV delay has been proposed to avoid ventricular pacing. The present study aimed to evaluate ventricular stimulation in SSS patients with DDDR pacemakers with a long AV delay. Methods and Results Thirty eight patients treated with DDDR pacemakers with a fixed long AV delay (300 ms) were studied. Data from the pacemaker event recorder were retrieved after 3 months and every year after implantation. Ten patients underwent 24h Holter recording. Mean follow-up was 11.9 +/- 8.3 months. Median daily number of paced events in the ventricle was 2659 (25th-75th percentiles: 775-21 315) with a large inter-individual variation. The proportion of Faced events in the ventricle correlated weakly with the baseline PQ interval (Spearman's rho 0.331, P=0.043). In 12/38 patients the mean daily number of paced events in the ventricle exceeded 10 000. During 24 h Holter recording, pacemaker arrhythmias caused by repetitive retrograde atrioventricular conduction, known as VA (ventriculoatrial) conduction, occurred in five out of 10 patients. Conclusion DDDR pacing with a fixed long AV delay is inefficient in reducing ventricular pacing in one third of patients and is associated with a high risk of arrhythmias caused by repetitive retrograde AV conduction, and therefore cannot be recommended for general use in SSS patients.