Low Atrial Fibrillatory Rate Is Associated With Poor Outcome in Patients With Mild to Moderate Heart Failure

Abstract

Background— Atrial fibrillatory rate (AFR) is a measure of atrial remodeling caused by atrial fibrillation (AF), and its acceleration negatively affects outcome of interventions for persistent AF. However, the prognostic value of AFR in patients with congestive heart failure (CHF) has not been studied. We sought to evaluate whether AFR can predict outcome in patients with mild to moderate (New York Health Association II–III) CHF. Methods and Results— High-resolution 20-minute long Holter ECGs obtained from 169 CHF patients with AF at enrollment were analyzed. AFR was estimated using spatiotemporal QRST cancellation and time–frequency analysis. The patients were followed for a median of 44 months, with primary end point defined as total mortality and secondary end points as sudden death and heart failure death. Atrial signal quality was sufficient for AFR estimation in 142 patients (mean age 69±11 years, 101 male). Of those, 48 patients died during follow-up, including 18 because of CHF progression. Mean AFR was 390±60 fpm and decreased with age ( r =−0.3, P <0.001). Patients with AFR ≤371 fpm (lower tertile) had 44% 3-year mortality as compared with 26% with higher AFR. Lower AFR was an independent predictor of all cause mortality (HR=1.99, 95% CI=1.09–3.63, P =0.025) and CHF death (HR=3.74, 95% CI=1.38–10.14, P =0.010) after adjustment for significant clinical covariates in multivariable Cox analysis. Conclusions— In CHF patients with AF, reduced AFR assessed using noninvasive approach is associated with increased risk of death because of heart failure progression, and may be considered a predictor of outcome.