Background: According to the current guidelines, atrioventricular (DDD) pacing is superior to atrial pacing (AAI) in the treatment of sick sinus syndrome (SSS).

Aim: To compare outcomes of AAI and DDD pacing in patients with SSS during long-term follow-up.

Methods: We studied 809 patients, including 86 patients in the AAI group (57 women, mean age 65 ± 15 years) and 723 patients in the DDD group (406 women, mean age 71.5 ± 10 years). Evaluation of outcomes of AAI and DDD pacing in SSS was based on the analysis of medical records of patients who underwent pacemaker implantation.

Results: Average duration of follow-up was 52 ± 25 months. In the AAI group, 63 of 86 patients remained without intervention. In the DDD group, 661 of 723 patients did not require surgical intervention. Overall, 105 patients died, including 13 in the AAI group and 92 in the DDD group (p = 0.4516). In the AAI group, a high degree atrioventricular block occurred on average after 46.3 ± 8.8 months and its incidence was estimated at 0.85% per year. Atrial fibrillation (AF) developed in 8 patients in the AAI group and 81 patients in the DDD group (p = 0.23). Among aetiological factors of an increased risk of developing AF, only the presence of tachycardia-bradycardia syndrome (hazard ratio [HR] 11.31) and the absence of antiarrhythmic therapy (HR 4.23) significantly increased the risk of AF. Urgent reoperation was needed in 23 patients in the AAI group and 62 patients in the DDD group (p < 0.01). Log-rank test analysis showed a significant effect of the development of AF on the risk of reoperation in this group (p = 0.0420). Lead-related complications were noted in 6 patients in the AAI group and 49 patients in the DDD group (p = 0.94). After 45 months, the risk of reoperation in the AAI group increased significantly due to a need for ventricular lead implantation.

Conclusions: 1. Atrial stimulation is safe in SSS but it may be associated with an increased risk of ventricular lead implantation if atrioventricular block or persistent AF with slow ventricular rate develops. 2. DDD and AAI groups did not differ significantly in terms of survival, development of persistent AF, and lead-related complications. 3. Tachycardia-bradycardia syndrome and the lack of antiarrhythmic treatment with beta-blocker and amiodarone increased the risk of persistent AF during long-term follow-up. 4. A higher rate of reoperations in patients with AAI systems, related mainly to development of persistent AF, especially after the fourth year of follow-up, may justify DDD system implantation in SSS.