Abstract
BACKGROUND: Patients with sinus node dysfunction (SND) are at risk of atrial fibrillation (AF) after dual-chamber pacemaker implantation. AF is a risk factor for cardiovascular and cerebrovascular events. The location of atrial electrodes can influence AF occurrence. This study aimed to investigate the differences in the incidence of new-onset AF between low atrial septal (LAS) and right atrial appendage (RAA) pacing in patients with SND and explore the possible underlying mechanisms. MATERIALS AND METHODS: We included 155 patients with SND, including 83 and 72 who received LAS and RAA pacing, respectively. We collected baseline data, electrocardiogram indexes, and ultrasound cardiogram indexes, as well as postoperative complications, program testing data of the pacemaker, electrocardiogram indexes, and AF occurrence during 1-year follow-up. RESULTS: The operative duration was significantly longer in the LAS group than in the RAA group (P < 0.001). The intraoperative P-wave amplitude was significantly smaller in the LAS group than in the RAA group (P =0.001). The P-wave duration and cumulative percentages of ventricular pacing (Cum % VP) in the LAS group were significantly lower than those in the RAA group (P < 0.001 and P =0.039, respectively). At 1-year follow-up, the incidence of new-onset AF was significantly lower in the LAS group than in the RAA group (16.9% vs. 36.1%, hazard ratio [HR]: 0.363, 95% confidence interval [CI]: 0.156-0.846, P = 0.019). The independent risk factors for new-onset AF at 1-year follow-up were combined bundle branch block (odds ratio [OR] 8.015, 95% CI 1.232-52.132, P = 0.029), large left atrium (OR 5.812, 95% CI 1.202-28.088, P= 0.029), and prolonged postoperative P-wave duration (OR 1.027, 95% CI 1.009-1.045, P = 0.018). LAS pacing was associated with a reduced risk of postoperative AF occurrence (OR 0.072, 95% CI 0.010-0.542, P = 0.011). CONCLUSION: For patients with SND after dual-chamber pacemaker implantation, AF incidence within 1 year after LAS pacing was significantly lower than that after RAA pacing. LAS pacing could shorten the postoperative P-wave duration, an independent risk factor for new-onset AF, and LAS pacing effectively reduced the Cum % VP, which may be the underlying mechanism by which LAS pacing prevents postoperative AF occurrence.