Right atrial pacing and the risk of postimplant atrial fibrillation in cardiac resynchronization therapy recipients

Background In patients with cardiac resynchronization therapy (CRT) devices, right atrial (RA) pacing introduces a significant prolongation in interatrial conduction time, delaying left atrial mechanical systole and curtailing left ventricular filling. The resultant increase in left-sided filling pressures may facilitate atrial fibrillation (AF). We sought to determine whether the extent of RA pacing influences the incidence of AF after CRT. Methods Consecutive CRT patients (n = 309) followed at our institution were retrospectively studied for percentage of RA pacing and incidence of high atrial rates, as determined by regular device interrogations. Additional clinical data were collected from the medical record. Results The mean follow-up was 18.1 +/- 13.3 months, during which 209 (67.6%) patients had at least 1 detected high atrial rate episode consistent with AF. Higher percentages of RA pacing were associated with a greater risk of postimplant AF, with its incidence increasing incrementally with quartiles of RA pacing: 44.6%, 64.3%, 79.7%, and 81.6%, respectively (P <.001). After controlling for all factors predictive of postimplant AF on univariate analysis (right atrial pacing quartile, follow-up duration, mitral regurgitation severity, and prior AF history), RA pacing quartile remained a significant predictor of post-CRT AF (hazard ratio 1.92, 95% CI 1.40-2.62, P <.001) upon multivariate analysis. In addition to predicting AF incidence, higher RA pacing quartiles were also associated with significantly greater AF burden. (Conclusions Compared to atrial sensing, atrial pacing is associated with a 2-fold increased risk of post-CRT AF. Prospective comparison of DDD and VDD pacing modes in CRT is warranted.