Cardiovascular disease is one of the most significant causes of death in captive great apes.4 The most common pathological finding is idiopathic myocardial fibrosis, where cardiac muscle is replaced by connective tissue, leading to impaired cardiac function.3 The aim of this study was to compare the structure and morphology of 12 hearts of chimpanzees (Pan troglodytes) affected by different degrees of myocardial fibrosis using microcomputed tomography. Findings were compared with histologically defined levels of interstitial and replacement fibrosis and sex and age of the animals at the time of death. In half of the hearts, areas of mineralisation were detected within the heart. In three of them, an area of ossification was present, and it was localised within the right fibrous trigone, between the mitral and tricuspid valves. Another three chimpanzees presented multiple foci of mineralisation. All animals affected by advanced myocardial fibrosis revealed ossification, cartilaginous metaplasia or mineralisation, while animals that did not show myocardial fibrosis had no bone nor mineral deposition, independently of their age. The presence of an os cordis in the cardiac skeleton of the heart has been described in ruminants, camelids, and otters, but never in great apes.1,2 The development of bone tissue in the heart of chimpanzees affected by myocardial fibrosis could influence the risk of cardiac arrhythmias and sudden death. This is the first study using microcomputed tomography to analyse cardiac structure in great apes.
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