Introduction: The current European and North Ame-rican guidelines on cardiac pacing generally recom-mend the implantation of dual chamber pacemakers in patients with sick sinus syndrome, because there is an additional risk for atrial fibrillation and reoperation for upgrade in patients initially receiving a single chamber atrial device. Many health assurance systems however can not sustain the costs of dual chamber device im-plantation in all patients.

Objective: Thus, the present study aimed to compare the evolution of the single (atrial) chamber (AAIR) and dual chamber (DR) pacemaker patients along one year of follow-up.

Methods: We retrospectively enrolled 44 patients im-planted in Clinical Rehabilitation Hospital Cluj-Na-poca and divided them into two subgroups: single chamber (AAIR – 28 patients) and dual chamber (DR – 16 patients) pacemaker; in both subgroups the AV conduction was assessed as normal at the time of im-plantation. At one year follow-up visit we assessed the percentage of the atrial and ventricular pacing, the occurrence of atrial fibrillation and the occurrence of atrioventricular block.

Results: The study group consisted of 22 males (mean age 68 years) and 22 females (mean age 65 years). The ration males/females remained the same in the two subgroups, 1:1 and also the mean age (67.3 ± 9.9 years in AAIR subgroup vs. 65.06 ± 8.46 years in DR subgroup). The LA size (39.74 ± 5.5 vs. 40.5 ± 7.5 mm), the indi-cation for pacing (sinus bradycardia 46.4% vs. 43.7%, tachy-brady syndrome 53.6 vs. 56.3%), the prevalence of underlying cardiac disease (ischemic heart disease-10.7% vs. 18.7%; valvular heart disease 25% vs. 31.2%) comorbidities (COPD, diabetes) and antiarrhythmic medication did not differ significantly. At one year follow-up visit we observed an increase in atrial pacing percentage (58.4% to 68.12%, due to betablockers and amiodarone recommended after implantation) but no change in ventricular pacing percentage in DR patients suggesting that AV conduction remained normal des-pite antiarrhythmic drugs. Atrial fibrillation occurred in 17.9% of the AAIR subgroup and 25.4% in the DR subgroup (p=0.241).

Conclusions: In our cohort, the single chamber atri-al pacing proved to be safe and effective in sick sinus syndrome patients with preserved atrioventricular conduction