Minimizing ventricular pacing to reduce atrial fibrillation in sinus-node disease.
BACKGROUND
Conventional dual-chamber pacing maintains atrioventricular synchrony but results in high percentages of ventricular pacing, which causes ventricular desynchronization and has been linked to an increased risk of atrial fibrillation in patients with sinus-node disease.


METHODS
We randomly assigned 1065 patients with sinus-node disease, intact atrioventricular conduction, and a normal QRS interval to receive conventional dual-chamber pacing (535 patients) or dual-chamber minimal ventricular pacing with the use of new pacemaker features designed to promote atrioventricular conduction, preserve ventricular conduction, and prevent ventricular desynchronization (530 patients). The primary end point was time to persistent atrial fibrillation.


RESULTS
The mean (+/-SD) follow-up period was 1.7+/-1.0 years when the trial was stopped because it had met the primary end point. The median percentage of ventricular beats that were paced was lower in dual-chamber minimal ventricular pacing than in conventional dual-chamber pacing (9.1% vs. 99.0%, P<0.001), whereas the percentage of atrial beats that were paced was similar in the two groups (71.4% vs. 70.4%, P=0.96). Persistent atrial fibrillation developed in 110 patients, 68 (12.7%) in the group assigned to conventional dual-chamber pacing and 42 (7.9%) in the group assigned to dual-chamber minimal ventricular pacing. The hazard ratio for development of persistent atrial fibrillation in patients with dual-chamber minimal ventricular pacing as compared with those with conventional dual-chamber pacing was 0.60 (95% confidence interval, 0.41 to 0.88; P=0.009), indicating a 40% reduction in relative risk. The absolute reduction in risk was 4.8%. The mortality rate was similar in the two groups (4.9% in the group receiving dual-chamber minimal ventricular pacing vs. 5.4% in the group receiving conventional dual-chamber pacing, P=0.54).


CONCLUSIONS
Dual-chamber minimal ventricular pacing, as compared with conventional dual-chamber pacing, prevents ventricular desynchronization and moderately reduces the risk of persistent atrial fibrillation in patients with sinus-node disease. (ClinicalTrials.gov number, NCT00284830 [ClinicalTrials.gov].).
Sweeney
Michael O
MO
Cardiac Arrhythmia Service, Brigham and Women's Hospital, Boston, MA 02115, USA. mosweeney@partners.org
Bank
Alan J
AJ
Nsah
Emmanuel
E
Koullick
Maria
M
Zeng
Qian Cathy
QC
Hettrick
Douglas
D
Sheldon
Todd
T
Lamas
Gervasio A
GA
D000368:Aged; D001281:Atrial Fibrillation / Q000517:prevention & control*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006352:Heart Ventricles; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D010138:Pacemaker, Artificial / Q000009:adverse effects; D012804:Sick Sinus Syndrome / Q000401:mortality / Q000628:therapy*; D012849:Sinoatrial Node