The understanding of the pathogenetic mechanisms leading to the structural restructuring of the myocardium and the formation of atrial fibrillation (AF) is expanding. Unfortunately, there is still no single theoretical understanding that would allow us to fully explain the pathogenesis and, thus, approach 100% results of the effectiveness of therapy. First of all, when receiving patients with AF (and these are more often patients of older age groups), the doctor evaluates the state of carbohydrate and fat metabolism and atrial volume indicators according to echocardiography. While the state of protein metabolism in some cases remains without the close attention of the clinician. The article analyzes the factors leading to a violation of protein metabolism (protein synthesis) in patients with heart rhythm disorders. Among them are disorders of the nutritional status (including a decrease in the intake of protein, magnesium, vitamin D), disorders in the digestive system, hormonal disorders (age-related disorders of the hormonal status of patients, an increase in sarcopenia with age, the addition in some cases of a metabolic syndrome with the formation of insulin resistance). Attention is focused on the effect of IGF-1 (insulin-like growth factor-1) on the myocardium. The question is raised about the prognostic value of the levels of IRF-1 and IRF-binding proteins (IGFBP) in the blood serum for the development of AF.