Heart failure remains one of the most common causes of hospitalization, disability, and mortality in the working population in the world, particularly in Ukraine; it has a high prevalence, an unfavorable prognostic course, and also causes significant economic costs. The prevalence of heart failure (HF) in the general population is 1.5 - 2.0%, and among people over 65 years old - 6 - 10% [10]. The main etiological cause of the development of chronic heart failure (CHF) is coronary heart disease (CHD), which is confirmed by the data of multicenter studies. One of the features of CHF is the high heterogeneity of its clinical manifestations and the absence of absolutely pathognomonic symptoms, which often leads to late diagnosis and deterioration of the prognosis of the course of the disease [1-6]. In the last decade, biomarkers for the diagnosis and prognosis of HF have been actively researched in search of the "ideal" one that can characterize the activation of all links of the HF syndrome and provide additional information about natriuretic peptides (NAUP). Given the extremely complex and multifaceted biochemical interactions that underlie the pathophysiology of CHF, scientists are paying more attention to a multimarker strategy for the diagnosis and risk stratification of CHF.Aim. The purpose of the paper is to investigate the role of brain natriuretic peptide (BNP), NT-pro BNP, galectin-3, s-ST2 in the development of heart failure in patients with atrial fibrillation.Material and methods. 468 patients aged 45-65 years (54,3±7,2 years) and 56 healthy people were included in the study. Among the examined were 234 (50,0%) women and 234 (50,0%) men. Group I – control, 56 practically healthy individuals; Group II - patients with CHF without AF (n=234); III group - patients with CHF and AF (n=234).Diagnoses of AF and HF were carried out according to the clinical protocol for providing medical care to patients with atrial fibrillation and heart failure, confirmed by the order of the Ministry of Health of Ukraine №436 of 07.03.2006. and according to the 2021 Recommendations of the European Society of Cardiology (ESC) on the diagnosis and treatment of acute and chronic heart failure. In addition to the general clinical examination, an enzyme immunoassay was also performed to determine the content of brain natriuretic peptide, NT-pro BNP, galectin-3 and sST-2 in the blood.Results. The analysis of structural changes of the myocardium in various phenotypes of CHF revealed a probable increase in the transverse size of the left atrium by 18,5%, the index of the size of the left atrium by 25,4%, the area of the left atrium by 25,3%, the volume of the left atrium by 21,6% and left atrial volume index by 10,1% in patients with CHF and concomitant AF.The study founds a probable increase in the levels of NT-pro BNP (by 50,1%; p<0,05) and brain natriuretic peptide (by 47,3%; p<0,05) in patients with AF and CHF. With an increase in the size of the left atrium against the background of CHF and AF, a probable increase in the concentration of galectin-3 (by 24.3%, p<0.05) and a probable increase in the level of sST-2 (by 41.4%, p<0, 05) were set. It has been proven that an important aspect of the phenotype of CHF with accompanying AF is the enlargement of the left atrium (LA), which probably correlates with the content of brain natriuretic peptide (BNP) (r=0,35; p<0,05), as well as with sST-2 content (r=0,41; p<0,05).