Renal dysfunction is highly prevalent among patients with atrial fibrillation (AF) and confers an increased risk of thrombotic and bleeding complications. We evaluated the effect of renal function on prognosis in anticoagulated patients with AF and assessed the changes in renal function during a long-term follow-up period. We recruited 978 consecutive stable anticoagulated patients with AF from our outpatient anticoagulation clinic (international normalized ratio 2.0 to 3.0 within the previous 6 months). The estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Disease equation at inclusion and 2 years of follow-up. Adverse events were recorded during follow-up (thrombotic/vascular events, major bleeding episodes, and mortality). Longitudinal changes in renal function were analyzed in 886 patients (90.6%). At baseline, the median eGFR using the Modification of Diet in Renal Disease equation was 70.24 ml/min/1.73 m(2) (interquartile range 46.79 to 72.52). During follow-up, a low eGFR was associated with thrombotic/vascular events, with every 30 ml/min/1.73 m(2) eGFR decrease (hazard ratio 1.42, 95% confidence interval [CI] 1.11 to 1.83, p = 0.006), bleeding (hazard ratio 1.44, 95% CI 1.08 to 1.94, p = 0.015), and mortality (hazard ratio 1.47, 95% CI 1.13 to 1.91, p = 0.004). After excluding patients with a baseline eGFR <30 ml/min/1.73 m(2), the mean eGFR in our cohort decreased >10 ml/min/1.73 m(2) in 181 patients (21%) during the follow-up period. The variables associated with severe renal impairment during follow-up were heart failure (odds ratio 3.58, 95% CI 1.36 to 9.42, p = 0.010), basal eGFR (odds ratio 6.34, 95% CI 2.44 to 16.50, p <0.001), and CHADS2 (Congestive heart failure, Hypertension, Age >75 years, Diabetes mellitus, and previous Stroke or transient ischemic attack [doubled]) score (odds ratio 1.63, 95% CI 1.19 to 2.23, p = 0.003). In conclusion, the presence of impaired renal function was closely related to thrombotic/vascular events, bleeding, and mortality in anticoagulated patients with AF. During follow-up, 1/5 of the patients had significant impairment in renal function. Importantly, normal or mild renal dysfunction at baseline did not exclude the subsequent development of severe renal dysfunction during the follow-up period.
Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.