Atrial fibrillation is an independent determinant of increased NT-proBNP levels in outpatients with signs and symptoms of heart failure.

Background: N-terminal pro-B-type natriuretic peptide (NT-proBNP) is increasingly used in the diagnosis and prognostic assessment of heart failure; however, the possible influence of atrial fibrillation on BNP is still a matter of controversy. We assessed the influence of atrial fibrillation on NT-proBNP levels in outpatients with signs and symptoms of heart failure.

Methods: Consecutive outpatients (n = 306) referred to a university hospital heart-failure clinic for evaluation of signs and symptoms of heart failure underwent clinical and echocardiographic assessment and had their NT-proBNP levels determined in a sandwich chemiluminescent immunoassay with two antibodies on an Elecsys analyzer. The influence of atrial fibrillation on NT-proBNP levels was assessed using a non-parsimonious linear regression model with propensity score adjustments to balance for possible confounders.

Results: Atrial fibrillation was associated with increased NT-proBNP levels in patients with (median concentration 1944 vs. 1390 pg/ml) and without (1093 vs. 172 pg/ml) underlying structural disease (P < 0.001). In a linear regression model with a propensity score, atrial fibrillation emerged as an independent determinant of NT-proBNP levels (P = 0.023), even after allowing for possible confounders (left ventricular ejection fraction and end-diastolic diameter, left atrial diameter, mitral insufficiency, age, sex, NYHA class or heart rate).

Conclusions: Atrial fibrillation is an independent determinant of increased NT-proBNP levels. This association should be taken into account when NT-proBNP levels are used in the diagnosis of heart failure in patients with atrial fibrillation.