A Snapshot of Four-Chamber Adipocyte Distribution in the Human Heart.

Introduction: The distribution of adipose tissue and fibrosis in the heart is important because of its associations with cardiovascular conditions. However, research on the specific locations of adipocytes and fibrosis across the four cardiac chambers of the heart remains limited. Our study aimed to quantify the distribution of adipocytes and fibrosis across the four chambers of the human heart and to relate these structural findings to the causes of death in the post-mortem cases. Materials and Methods: As part of routine cardiac examination, images of Masson Trichrome-stained transverse myocardial slices from each of the four chambers of the heart of 52 post-mortem cases were analysed for adipocyte, fibrosis and cardiomyocyte area. Results: The greatest adipocyte area was observed in the right atrium (∼45%), with both the right atrium and left atrium having the greatest fibrosis formation (∼20-23%), whereas the right ventricle (8%) had substantially more adipocytes compared to the left ventricle (∼0.6%), but rather similar levels of fibrosis (∼3-4%). The post-mortem cases that were diagnosed with a cardiac cause of death had greater adipocyte area and less cardiomyocyte area in the left ventricle compared to cases without a cardiac cause of death. Discussion and Conclusion: Our descriptive study suggests that adipocyte and fibrosis distribution are clearly different in the four chambers of the heart, and that the location might be important for the development of cardiovascular diseases and potential cardiac death.