The morphological background of the left atrial appendage thrombosis (review)

The clinical significance of atrial fibrillation is largely associated with the risk of thromboembolic complications, which are most often caused by the formation of a thrombus in the left atrial appendage. The aim of the study was to systematize the data presented in the literature on the role of morphological features of the left atrial appendage in the development of atrial thrombosis and thromboembolic complications in patients with atrial fibrillation. Materials and research methods consisted of searching for articles in the RSCI and PubMed (MEDLINE) databases, using the following keywords: «left atrial appendage», «left atrial thrombosis», «epicardial fat», «atrial fibrillation». As a result of a meta-analysis of the literature, it was found that a number of studies have shown the likelihood of thrombus formation in the left atrial appendage and its anatomical features interrelated, in particular, the likelihood of thrombosis in the anatomical type of the left atrial appendage in the form of a «chicken wing» significantly lower than with other variants of its structure. However, the question of the reasons for the predominant formation of blood clots in the appendage of the left rather than right atrium remains unclear. One of the possible reasons may be the inherent endocrine function of the left atrial appendage, which is expressed in the secretion of a number of biologically active substances, in particular, natriuretic peptide. Another possible reason for the predominant formation of blood clots in the left atrial appendage may be its close contact with the atrial depot of epicardial fat, the excess of which plays an important role in the development of a number of cardiovascular diseases. The question of the morphological prerequisites for the development of thrombosis mainly in the left atrial appendage seems to be insufficiently studied. The study of this issue can improve the effectiveness of prevention of thromboembolic complications in atrial fibrillation.