Assessment of factors affecting plasma BNP levels in patients with chronic atrial fibrillation and preserved left ventricular systolic function

Background: Several studies have reported that plasma brain natriuretic peptide (BNP) levels are increased in patients with chronic atrial fibrillation (AF). The objective of this study was to assess the factors influencing plasma BNP levels in patients with chronic AF and preserved left ventricular (LV) systolic function. Methods: Transthoracic echocardiography was performed in 104 patients (48 men, 56 women; mean age, 63.9 ± 10.7 years) with chronic AF. At the same time, plasma BNP levels were measured with a Triage^R kit (Biosite, San Diego, CA). Results: Women, long duration of AF, and hypertension were more prevalent in the highest quartile group of BNP levels than in the lowest quartile of BNP. Significant correlations were observed between plasma BNP levels and the following: mitral E velocity (r = 0.343), mitral annular E′ velocity (r = - 0.402), ratio of mitral E velocity and mitral annular E′ velocity (r = 0.487), left atrial(LA) size (r = 0.653), LA volume index (r = 0.775), right atrial (RA) volume index (r = 0.563), maximal velocity (V_max) of mitral regurgitation (MR) (r = 0.448), tricuspid regurgitation (TR) V_max (r = 0.532) and LV mass index (r = 0.581). In stepwise multiple linear regression analysis, LA volume index (β = 0.326, p < 0.001), LV mass index (β = 0.395, p < 0.001) and duration of AF (β = 0.492, p < 0.001) independently predicted plasma BNP levels in the study subjects. The patients with increased LA volume index exhibited a longer duration of AF, larger RA volume index and LV mass index, higher MR V_max, TR V_max and plasma BNP level. Conclusions: LA volume index, LV mass index and duration of AF are independent predictors of plasma BNP levels in patients with chronic AF and preserved LV systolic function.