[Changes in NT-proBNP levels in patients with atrial fibrillation related to heart failure].

INTRODUCTION: NT-proBNP, a well-established diagnostic and prognostic marker in clinical practice, is significantly elevated in individuals with atrial fibrillation (AF), even in absence of heart failure or major structural heart disease. OBJECTIVES: The aim of this study was to determine the cut-off value of NT-proBNP for diagnosis of heart failure in individuals with atrial fibrillation. METHODS: We compared 44 patients (25 male/19 female) with AF and concomitant overt heart failure [age 76 (62-82) years; median (interquartile range - IQR)] versus 29 patients (16 male/13 female) with AF with no signs of heart failure [age 59 (50-67) years; median (IQR)]. We considered the underlying causes of heart failure and its severity, comorbidities, echocardiographic and selected laboratory parameters, the body mass index as well as the treatment at discharge. We determined the cut-off value for heart failure and major structural heart disease using ROC curve analysis. RESULTS: Median NT-proBNP in the group of patients with AF and concomitant heart failure was 3 218 ng/l (IQR 1 758-7 480 ng/l) vs 981 ng/l (IQR 431-1 685 ng/l) in the group of patients with AF with no signs of heart failure; this difference was statistically significant (p < 0.001). The level of NT-proBNP higher than 1 524 ng/l in patients with AF was diagnostic of major structural heart disease and pointed towards a possible heart failure (sensitivity 80%, specificity of 76%, accuracy 78%, positive predictive value 83%, negative predictive value 71%). The NT-proBNP levels significantly correlated with age (p < 0.001), left atrial diameter (p < 0.01) and furosemide dose at discharge (p < 0.05). The NT-proBNP levels significantly negatively correlated with left ventricular ejection fraction (p < 0.001) and body mass index (p < 0.05). CONCLUSION: We found out that NT-proBNP is significantly elevated in patients with AF with preserved left ventricular function and in absence of heart failure and significantly correlates with age, left ventricular ejection fraction, left atrial diameter, body mass index and the furosemide dose necessary to achieve cardiac compensation. Furthermore, we determined the NT-proBNP cut-offvalue predictive of a possible heart failure in patients with AF.