28 September, 2015:
Growing evidence suggests a role of cardiovascular fat (epicardial + paracardial + aortic) in the pathogenesis of coronary heart disease. In order to study the relationship between deposits of cardiovascular fat and the menopause, El Khoudary and colleagues studied 456 women with an average age of 50 years from the SWAN heart cohort. Sex hormone levels were measured and cardiovascular fat volume was quantified by computerized tomographic scan. Late peri/postmenopausal women had greater volume of cardiovascular fat as compared with pre/early perimenopausal women independent of age and obesity. Lower estradiol concentrations were associated with greater cardiovascular fat volumes. The authors concluded that cardiovascular fat perhaps plays a role in the higher risk of coronary heart disease reported in women after the menopause .
The relationship between the menopause and increased weight is not completely clear; what is clear is that the cessation of ovarian function is associated with redistribution of body fat, increased abdominal fat and waist circumference, all known cardiovascular risk factors . Accumulation of abdominal fat is greatest in postmenopausal women and may play a role in the increased prevalence of cardiovascular risk observed after menopause onset. Adipose tissue is not merely a silent organ for energy storage, but rather an active source of multiple bioactive factors called adipokines, peptides that signal the functional status of adipose tissue to targets in the brain, liver, pancreas, immune system, vasculature, muscle, and other tissues. Secretion of adipokines (adiponectin, fibroblast growth factor 21, vaspin, apelin, progranulin, etc.) is altered in adipose tissue dysfunction and may contribute to a spectrum of obesity-associated conditions such as cardiovascular and metabolic, chronic inflammatory, and several malignant diseases .
For some years it has been known that not only abdominal fat is associated with increased cardiovascular risk, but also that the adipose tissue surrounding the heart is associated with this increase . Cardiac adipose tissue could locally modulate the morphology and function of the heart and vasculature, thereby possibly playing a role in adiposity-related atherosclerosis. Iacobellis and colleagues have shown that epicardial adipose tissue is significantly related to carotid intima-media thickness, an index of subclinical atherosclerosis. Variations in adipokine secretion from the cardiovascular fat could be evoked among the potential explanatory mechanisms of this effect .
The study of El Khoudary and colleagues takes a step further in the understanding of the relationship between cardiovascular fat and female cardiovascular disease. They point to a clear relationship between the menopause, endogenous estrogen levels and cardiovascular fat and therefore cardiovascular risk in late peri/postmenopausal women, indicating the importance of avoiding weight increase at this stage of female life. Therefore, this study contributes to medical knowledge that in the near future may even have therapeutic implications. However, from a diagnostic point of view, it is unlikely to be useful, since costs related to cardiovascular fat measurement are not lower when compared to other more simple diagnostic tools. For instance, since abdominal obesity has a good correlation with cardiovascular fat, it would much easier to regularly measure waist circumference in our patients in order to have a good assessment of cardiovascular risk. A large multinational study showed that a waist circumference greater than 88 cm has 84.8% sensitivity, 69.9% specificity and a 60.4% positive predictive value in the detection of the metabolic syndrome, a strong cardiometabolic risk marker . In summary, the present study of El Khoudary and colleagues provides a nice contribution to medical knowledge that could have a practical application in the near future.
Dr Juan Enrique Blümel
Associate Professor, Universidad de Chile, Santiago de Chile, Chile
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