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Vol. 27, Art. 33 (pp. 777-814)    |    2026       

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The role of myocardial fibrosis and cardiac adiposity in the pathogenesis of atrial fibrillation

Silkin M.S., Mitrofanova L.B.

Federal State Budgetary Institution “Almazov National Medical Research Centre” of the Ministry of Health of the Russian Federation, 197143, Russian Federation, Saint- Petersburg, 2, Akkuratova str. Department of Pathological Anatomy with a Clinic.

Brief summary

This scientific review systematizes current concepts regarding the role of myocardial fibrosis and epicardial adipose tissue as the fundamental pathomorphological substrates of atrial fibrillation. The literature search and selection were conducted using the PubMed, Scopus, eLIBRARY, and Web of Science electronic databases for the period from 1995 to 2026. The search was performed using keywords and their combinations. The review included original experimental, clinical-morphological, and autopsy studies, as well as international clinical guidelines. The paper provides a detailed examination of the primary molecular and cellular cascades of fibrogenesis, including the signaling pathways of transforming growth factor-beta, angiotensin II, and hypoxia-inducible factor-1-alpha. The impact of hemodynamic, ischemic, and oxidative stress on the transformation of fibroblasts into myofibroblasts is described. The review analyzes the role of disruptions in the spatial architecture of the extracellular matrix, particularly changes in the ratio between type I collagen and type III collagen, which promote endo-epicardial dissociation and delayed impulse conduction. Furthermore, the study substantiates the significance of epicardial adipose tissue as a paracrine-active organ that secretes profibrotic cytokines and infiltrates the atrial myocardium, creating substrates for micro-re-entry circuits. The contradictions present in the literature concerning unified threshold values for pathological fibrosis and the diagnostic utility of circulating biomarkers are specifically highlighted. The review concludes by emphasizing the high importance of morphological studies for standardizing the criteria for the structural remodeling of the atria.


Key words

atrial fibrillation; atrial fibrosis; pathological anatomy; extracellular matrix; type I and III collagen; epicardial adipose tissue; myofibroblasts; structural remodeling; literature review.

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