This is a prospective, randomized, double blinded, multi-center, controlled study to evaluate the clinical impact at 18 months after DDD implantation of alternative pacing site (RVOTs and RVA) and the different conduction path (RVOTs and AV node) on cardiac dysfunction prevention.

Ventricular pacing is unavoidable in many patients because of unreliable or absent AV conduction, or permanent AF. In recognition of this need, interest has focused on alternative site(s) ventricular pacing to maximize pumping function. These sites include the RV septum, His bundle, various LV sites, and combination of LV and RV (biventricular [BiV]). The RV outflow tract septum (RVOTs) seems to be the most promising site within the RV.

However, small enrollment and inconsistent experimental methods hinder the interpretation of these studies. Locations of alternative pacing sites were not clearly specified, were largely topographic, and lacked consistent anatomic designation. And what is more, there was no prospective, double-blind randomized, multi-center clinical trial which is design to test whether RVOTs pacing is superior to right ventricular apical pacing in preserving left ventricular systolic function and avoiding adverse left ventricular remodeling in patients with a normal left ventricular ejection fraction, ventricular synchrony and standard indications for pacing (sinus node dysfunction) in China. There was also no prospective, double-blind randomized, multi-center clinical trial which is design to test whether RVOTs pacing is not inferior to AAIR pacing in preserving left ventricular systolic function and avoiding adverse left ventricular remodeling in patients with a normal left ventricular ejection fraction, ventricular synchrony and sinus node dysfunction in the world.

So SJM China will sponsor a prospective, randomized, double blinded, multi-center, controlled study to evaluate the clinical impact at 18 months after DDD implantation of alternative pacing site (RVOTs and RVA) and the different conduction path (RVOTs and AV node) on cardiac dysfunction prevention.

Inclusion Criteria:

• Patients with only sinus-node dysfunction and meet pacing indication
• Patients with LVEF≥60% and with ventricular synchrony.
• Patients signed the written informed consent for the study
• Patients can endure the required follow up

Exclusion Criteria:

• Patients with atrial fibrillation
• Patients with atrial-ventricular block
• Patients with LBBB
• Patients with significant valvular disease
• Patients with severe hematopathy or severe renal inadequacy
• Patients with life expectancy < 1.5 year
• Patients who are in the period of pregnant or lactation
• Patients who are younger than 18 years old
• Patients who are ongoing other devices or agents study