The study protocol was developed by the staff of the Lomonosov Moscow State University. This study is devoted to the association between blood rheology, hemostasis and functional status in patients with chronic heart failure (CHF). The importance of this study is determined by the need for new approaches to diagnosis and treatment of elderly patients with cardiovascular diseases, especially in context of widespread CHF in population. The study focuses on non-cardiac causes of impaired tolerance to physical exertion and importance of blood in binding and delivering oxygen. A unique feature of this research is modern optical technologies and artificial intelligence. Diagnostic methods include measuring the microrheological blood parameters at the level of cells and blood samples using modern optical methods and digital image processing. The study aims to explore the role of erythrocytes as an indicator of cardiovascular health. The authors pay a particular attention to red cell distribution width as a quantitative measure of anisocytosis and a complex indicator associated with various pathological processes in chronic diseases. The authors will investigate deformability and aggregation of erythrocytes, as well as their adhesion to vascular endothelium that is crucial for adequate perfusion and oxygen delivery to peripheral tissues.