Does DDD pacing with minimized ventricular stimulation prevent atrial fibrillation in sinus-node disease?

BACKGROUND There are several cardiac pacing options available to patients with sinus-node disease (SND), but each is associated with clinical disadvantages and the optimum strategy has not been identified. OBJECTIVE To test the hypothesis that DDD (dual-chamber) pacing with minimal right ventricular (RV) stimulation reduces the risk of atrial fibrillation (AF) in patients with SND, when compared with traditional DDD pacing. DESIGN AND INTERVENTION This was a randomized, controlled trial conducted at 72 treatment centers in the US and Canada between 15 January 2003 and 19 December 2006. All patients were older than 18 years of age, had SND with symptomatic bradycardia, and had a QRS interval of 120msec or less. Exclusion criteria were second or third-degree atrioventricular block, persistent AF, two or more cardioversions for AF in the 6 months prior to enrollment, and a life-expectancy of 2 years or less. All patients underwent implantation of a dual-chamber pacemaker (Kappa® 700, Kappa® 900, EnPulse®, or EnRhythm® [all Medtronic Inc., Minneapolis, MN]). Participants who passed an atrial pacing test were randomly assigned to receive conventional DDD pacing or DDD pacing with minimal RV stimulation. Ventricular pacing was suppressed using new pacemaker technology preserving the intrinsic atrioventricular conduction, thereby preventing ventricular desynchronization. Patients were followed up 1 month after enrollment and at 6-month intervals thereafter. OUTCOME MEASURES The primary outcome measure was time to first persistent episode of AE Secondary end points were proportion of atrial and ventricular beats paced and rate of heart-failure hospitalizations (HFH). RESULTS From a total of 1,321 screened patients, 1,065 were enrolled and randomly assigned to one of the treatment groups (conventional pacing=535; minimal RV pacing=530). The mean age of patients was 72 years. The mean ejection fraction in both groups was 58%, and 38% of all patients had a history of AE At baseline, more patients in the conventional-pacing group were receiving antiarrhythmic medication than were those in the minimal-RV-pacing group (22.8% vs 17.5%; P= 0.03). After a mean follow-up period of 1.7 years, the median proportion of paced ventricular beats was much higher (99.0% vs 9.1%; P<0.001) and there was a higher incidence of persistent AF (12.7% vs 7.9%; P=0.004) among patients in the conventional-pacing group than among those in the minimal-RV-pacing group. Multivariate analysis revealed that the minimal RV pacing strategy was associated with a 40% reduction in the relative risk of persistent AF when compared with conventional pacing (hazard ratio 0.60, 95% CI 0.41-0.88; P=0.009). There was no significant difference between the treatment groups in the rate of HFH. CONCLUSION Minimization of RV stimulation during DDD pacing reduces the risk of persistent AF in patients with SND when compared with traditional DDD pacing. [ABSTRACT FROM AUTHOR]