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 atrioventricula r (AV) conduction receive dual chamber (DDDR) pacemakers. Programming a lon g AV delay has been proposed to avoid ventricular pacing. The present study aimed to evaluate ventricular stimulation in SSS patients with DDDR pacema kers 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 (25 th-75th percentiles: 775-21 315) with a large inter-individual variation. T he proportion of Faced events in the ventricle correlated weakly with the b aseline 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 retrograd e atrioventricular conduction, known as VA (ventriculoatrial) conduction, o ccurred in five out of 10 patients. Conclusion DDDR pacing with a fixed long AV delay is inefficient in reducin g ventricular pacing in one third of patients and is associated with a high risk of arrhythmias caused by repetitive retrograde AV conduction, and the refore cannot be recommended for general use in SSS patients.