Effects Of Minimizing Ventricular Pacing On Incidence Of Atrial Fibrillation In Patients With Sick Sinus Syndrome

Objective To explore the effects of minimizing ventricular pacing on incidence of atrial fibrillation(AF) in patients with sick sinus syndrome(SSS). Methods Patients with SSS who were implanted with DDD pacemakers from April 2004 to April 2008 were enrolled.They were randomized to conventional dual-chamber pacing group (56caces) and minimizing ventricular pacing group(56caces),and were follwed up at 3 month, and 6 month after implantation and then annually. Pacemaker interrogation, electrocardiogram, echocardiography were performed during follow-up.The main outcome measures was occurrence of atrial fibrillation. The second outcome measures were the changes in cardiac sizes and function measured by echocardiography (Including the left atrial diameter, left ventricular end-diastolic diameter and left ventricular ejection fraction) and the state of rehospitalizing for heart failure. Results Mean follow-up time was (33.7±17.1)months. The mean proportion of ventricular pacing significantly decreased in minimizing ventricular pacing group than in conventional dual-chamber pacing group(10.1%vs92.3%,P<0.001),but the mean proporation of atrial pacing were similar in two groups (73.6%vs72.8%,p=0.98).Cumulative paroxysmal atrial fibrillation was significantly less common in minimizing ventricular pacing group than in conventional dual-chamber pacing group(RR=0.65,95%CI 0.59~0.93,P=0.015). Compared with preimplantation,left atrial(LA),ventricular size and cardiac function were not changed significantly at each follow-up in minimizing ventricular pacing group. But two years later, the left atrial diameter was significantly enlarged in conventional dual-chamber pacing group compared with minimizing ventricular pacing group. The left ventricularsize and cardiac funcyion were not statistically changed between two groups. Conclusions Right ventricular apical pacing could lead to more atrial fibrillation events and enlarge LA diameter.In patients with SSS and normal atrioventricular conduction,A more careful selection of minimizing ventricular pacing is safe and feasible, and should be advocated.