Cardiomyopathy means disease of the heart muscle, and in HCM the left ventricle of the heart, which pumps blood through the aorta, the body's largest artery, is thickened. This thickening stops the heart expanding properly. Unfortunately many cats are asymptomatic or show very few symptoms, which can make HCM hard to diagnose and treat. Other possible symptoms can be similar to those of CRF, including lack of appetite, lethargy and vomiting. This is both life-threatening and extremely painful, and you should consult a vet as soon as possible.
Affected legs are likely to be cold to the touch.
Otherwise, HCM cannot be cured but it can be controlled by way of drugs. Unfortunately many drugs which help the heart condition put strain on the kidneys, so if your cat has both heart disease and CRF, discuss which drug to use with your vet. It must be emphasised that it is essential to treat heart disease if it is present, and that treating the heart disease must take precedence over treating the CRF, which is an academic problem if the heart stops beating. At present there is limited information available on this treatment in cats in the USA, although if your vet is a member of the Veterinary Information Network he or she might be able to obtain further information from them. This is often the treatment of choice in the USA, where a drug called Atenolol is used.