Background. According to the national registries of European countries and epidemiological studies, the prevalence of chronic heart failure (CHF) among adults is 2,0-5,0%, and increases due to age, in people aged over 70 years old it is 10,0-20,0%.Objective. To find out the specific features of remodeling of the left atrium and change of vasodilation factors in ischemic heart failure with reduced and preserved left ventricular ejection fraction and to establish correlation relationships.Methods. A full clinical examination of 153 patients with CHF (105 men and 48 women) was conducted to achieve this objective. The surveyed patients underwent clinical examinations; spectrophotometric parameters: quantification of markers of vasodilation, metabolites of monoxide nitrogen – nitrates and nitrites with Gris reagent; content of endothelial nitric oxide synthase (eNOS) in serum - ELISA for the set of Nitric Oxide Synthase 3, Endothelial (NOS3) Human ELISA Kit (Cloud-Clone Corp, USA). Electrocardiographic (ECG) examination was conducted in 12 standard conventional leads on electrocardiograph by the Hungarian production Heart Screen 112 D.Results. The 1st group of the examined patients with reduced LV EF prevails III (significant) degree LA dilatation in 33 (70.21%) cases, II (moderate) degree of LA dilatation was determined in 14 (29.78%), and I (initial) degree was not defined at all. In the 2nd group of the patients with preserved LV EF mainly the II degree of LA dilatation was determined in 44 (44.51%) cases, and decreased LA dilation in 39 (36.79%) cases (p<0.01), and III degree of LA dilation was defined in 23 (21.69%) cases (p<0.01). In patients with stable coronary heart disease, complicated by heart failure with reduced LV EF and II degree of LA dilatation, eNOS levels in the serum was 449.00±39.91 pg/ml, whereas in patients with stable coronary heart disease, complicated by heart failure with preserved LV EF and II stage of LA dilatation – 673.56±50.98 pg/ml (p<0.01). At III stage of LA dilatation in patients of the 1st group level eNOS was 344.20±51.98 pg/ml in the patients of the 2nd group – 616.90±36.49 pg/ml (p<0.01). At the same degree and with LA dilation in the patients of the 2nd group eNOS was 750.27±99.85 pg/ml. Conclusions. The structural and functional changes of the left atrium and changing factors of vasodilation in patients with stable coronary artery disease of II-III functional classes complicated by heart failure of I-III functional classes are studied. It is established that in the examined patients with stable coronary heart disease complicated by heart failure with reduced left ventricular ejection fraction mainly III (significant) degree of dilatation of the left atrium was determined, while in patients with stable coronary heart disease, complicated by heart failure with preserved left ventricular ejection fraction mainly II (moderate) degree of dilation of the left atrium was determined. In comparison with the results of research among the patients with stable coronary heart disease, complicated by heart failure with reduced left ventricular ejection fraction, and a group of patients with preserved left ventricular ejection fraction, it was determined a significant decrease in eNOS, nitrites, total amount of nitrites and nitrates.