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Abstract
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.
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.
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.
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.