Decreased Glomerular Filtration Rate and Markers of Left Atrial Stasis in Patients with Nonvalvular Atrial Fibrillation

BACKGROUND: It is currently unknown if the increased risk of stroke in subjects with chronic kidney disease and atrial fibrillation (AF) is due to the presence of left atrial stasis or to any other vascular or systemic conditions. METHODS: This was a retrospective study of 372 subjects undergoing evaluation during an AF episode. The following markers of left atrial stasis were sought on transesophageal echocardiogram: left atrial or left atrial appendage thrombus (LAAT), dense spontaneous echocardiographic contrast (DSEC), and low flow velocities (LFV) in the left atrial appendage. Subgroup comparisons were performed according to the level of estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration equation as follows: ≥90, 45-89.9, and <45 ml/min/1.73 m2. RESULTS: LAAT was found in 11.6%, DSEC in 29.0%, and LFV in 14.9% of cases. A significant increase in the prevalence of DSEC was observed in the lower categories of eGFR: 37.8% in eGFR <45 ml/min, 30.7% in eGFR 45-89.9 ml/min, and 17.0% in eGFR ≥90 ml/min (p = 0.009; γ for trend = 0.297, p = 0.002). The same was observed when assessing left atrial abnormality, i.e. the presence of at least one of the former transesophageal echocardiogram changes. On multivariate analysis, clinical parameters from CHADS2 (congestive heart failure, hypertension, age ≥75, diabetes mellitus and stroke) and CHA2DS2-VASc (age 65-74, history of vascular disease, and female gender along with the clinical variables from CHADS2) were predictors of transesophageal echocardiogram changes and an additive predictive value was found for eGFR. CONCLUSIONS: Our results suggest an association between compromised renal function as assessed through eGFR and markers of left atrial stasis in patients with AF. The increased risk of stroke in this population may be due to thromboembolism.