Abstract 1897: Right Atrial Pacing Increases the Risk of Atrial Fibrillation In Patients Undergoing Cardiac Resynchronization Therapy
Introduction: Cardiac resynchronization therapy (CRT) devices are often programmed to provide atrio-biventricular (DDD) pacing. However, right atrial (RA) pacing prolongs interatrial conduction, which delays left atrial systole and curtails left ventricular filling compared to atrial-tracked biventricular (VDD) pacing. The consequent increase in left-sided filling pressures may promote atrial fibrillation (AF).
Hypothesis: The burden of RA pacing will increase AF incidence after CRT.
Methods: All CRT patients (n=310) followed at our institution were retrospectively studied for RA pacing burden and incidence of high atrial rates, as determined by device interrogations. Additional clinical data were also obtained.
Results: Over a mean follow-up of 560 ± 400 days, during which 206 (66.7%) had at least one detected episode of high atrial rates consistent with AF, greater percentages of RA pacing were associated with an increased risk of post-implant AF. When divided into RA pacing quartiles (0–1%, 1–15%, 15–53%, and >53%), AF incidence was 45.8%, 62.9%, 78.7%, and 81.6%, respectively. RA pacing quartile (p<0.001), follow-up duration (p<0.001), mitral regurgitation severity (p=0.03), ischemic HF (p=0.02), and AF history (p<0.001) were each associated with post-CRT AF. There were no differences in HF or anti-arrhythmic drug usage, gender, LVEF, left atrial or LV dimensions, NYHA class, or duration of HF. Multivariate analysis demonstrated that only RA pacing quartile (HR 1.84; 95% CI 1.33–2.55; p<0.001) and prior AF (HR 4.13; 95% CI 2.01– 8.55; p<0.001) independently predicted post-CRT AF. When patients without prior AF were examined separately, only RA pacing quartile (p=0.013), follow-up duration (p=0.03), and afterload-reducing agents (p=0.004) differed significantly between those with and without post-CRT AF. Multivariate analysis demonstrated a HR of 1.46 (95% CI 1.08–1.98; p=0.015) for post-CRT AF with increasing quartiles of RA pacing.
Conclusion: Atrio-biventricular pacing increases the risk of post-CRT AF compared with atrial-tracked, biventricular pacing. Prospective comparison of DDD and VDD pacing in CRT is warranted.