Extracardiac Causes of Atrial Fibrillation

<jats:p>Atrial fibrillation (AF) is a common cardiac arrhythmia that increases cardiovascular morbidity and mortality. AF also has extracardiac causes. Gastrointestinal (GI) disorders are among them. Disorders of the two systems usually co-exist simultaneously, which indicates the existence of a very complex relationship between cardiac and gastrointestinal diseases. Thus, disturbances in the orderly activation and restoration of electrical excitation passing through the heart and gastrointestinal system (GIS) can lead to arrhythmogenesis. Changes in thyroid regulation may increase the inducibility of AF, especially in the elderly, who have been shown to have lower levels of thyroid-stimulating hormone (TSH) associated with an increased incidence of AF. One of the factors explaining the risk of AF in hyperthyroidism is the development of atrial fibrosis under the influence of thyroid dysfunction. The link between hypothyroidism and AF is less clear, though it is associated with several cardiovascular diseases that often coexist with AF. Several large clinical trials have not revealed a residual correlation between clinical or subclinical hypothyroidism and AF after adjusting for concomitant factors. There is no convincing evidence that the restoration of the euthyroid state directly affects the natural course of AF. So, it is necessary to clarify the general mechanisms of the occurrence and development of AF in these patients, which are present between the activity of the cardiac conduction system, gastrointestinal diseases and thyroid dysfunction. There is a need for a thorough examination of patients in this category and their dynamic monitoring not only by cardiologists, but also by gastroenterologists and endocrinologists.</jats:p>