Dietary Salt Intake Contributes to the Variation of B-Type Natriuretic Peptide Levels in Patients with Chronic Atrial Fibrillation

Abstract

We assessed the hypothesis that salt intake was associated with B-type natriuretic peptide (BNP) levels in patients with atrial fibrillation (AF), which could contribute to BNP variation. Consecutive 48 chronic AF patients who had no signs of heart failure and 103 hypertensive patients with sinus rhythm were included. We measured BNP, systolic blood pressure, and heart rate at the time of urinary sampling, which was used for the estimation of salt intake. We assessed the relationship of individual changes in BNP (δBNP) and changes in salt excretion (δNaCl) in 7 to 56 weeks. In AF patients, baseline BNP levels were 184±110 pg/ml and estimated salt excretion was 9.6±2.4 g/day. There was a positive correlation between δNaCl and percent changes in δBNP (%δBNP, r=0.45, p<0.01). No correlation was found between changes in heart rate and δBNP. Some trends toward positive correlation was observed between changes in blood pressure and %δBNP (p=0.073). Multiple regression analysis revealed that only δNaCl was associated with %δBNP (p<0.01). Baseline BNP levels in sinus rhythm patients were 33±25 pg/ml. No significant correlation was observed between δNaCl and %δBNP (p=0.14). In conclusions, salt intake was associated with BNP levels only in AF but not in hypertensive sinus rhythm patients, which might contribute to the wide variation of BNP levels in patients with AF.