Enlarged heart. Coloured chest X-ray of a 91 year old woman showing gross (severe) enlargement of the heart (red), known as cardiomegaly. Cardiomegaly can be symptomless and may only be detected on a chest X-ray. There are a variety of disorders that can cause cardiomegaly including hypertension or a weakening of the heart muscle (cardiomyopathy). It may also occur in response to strain on the heart such as in obesity. The gradual loss of heart function (heart failure) leads to breathlessness and exhaustion, even when at rest. Various drugs help in managing the symptoms with transplantation as a last resort.