Biomarkers of left atrial volume: a longitudinal study in patients with end stage renal disease

Left atrial volume (LAV) has recently emerged as a useful biomarker for risk stratification and risk monitoring in patients with end stage renal disease. We investigated the relationship between cardiac natriuretic peptides (atrial natriuretic peptide [ANP] and brain natriuretic peptide [BNP]) and norepinephrine (NE) with LAV and LAV changes over time in 199 end stage renal disease patients. At baseline, LAV was directly related to BNP (r=0.60), ANP (r=0.59), and NE (r=0.28; P<0.001), and these relationships held true in multiple-regression models adjusting for potential confounders (P< or =0.003). In the longitudinal study (17+/-2 months), LAV increased from 9.8+/-4.6 to 10.9+/-5.4 mL/m(2.7) (+11%). In a multiple linear regression model, BNP (beta=0.28; P=0.003), ANP (beta=0.22; P=0.03), and NE (beta=0.27; P=0.003) predicted LAV changes. The area under the receiver operating characteristic curve for predicting LAV changes (>3 mL/m(2.7) per year) of a risk score on the basis of standard risk factors was 0.72. Plasma BNP (+12%; P=0.004), ANP (+8%; P=0.03), NE (+8%; P=0.05) and midwall fraction shortening (+8%; P=0.05) increased the area under the receiver operating characteristic curve to a significant extent, whereas LV mass did not (+5%; P=0.18). Predictive models, including BNP, ANP, and NE, maintained a satisfactory discriminatory power for LAV and LAV changes also when tested by a bootstrap resampling technique. BNP and ANP are strongly related to LAV in the end stage renal disease patients and predict LAV changes over time in these patients. Because an increased LAV underlies diastolic dysfunction and/or volume overload (ie, potentially modifiable risk factors), the measurement of the plasma concentration of these compounds might be useful for risk stratification and for guiding treatment in dialysis patients.