There are essentially three types of heart diseases that cats get and these have different treatments.
Hypertrophic cardiomyopathy (HCM) is the most common form of feline heart disease. It occurs when the heart muscle wall becomes thickened and the inside of the heart becomes smaller. Less blood can be pumped with every beat and the heart has to work harder. A murmur can develop as the valves also become involved. As the cat ages the heart becomes thicker and less and less blood can be pumped. Fluid will accumulate in the lungs. This type of heart disease is seen in young to middle aged cats and is more common in purebreds such as Ragdolls and Persians. HCM can lead to blood clots or thromboembolisms as they are called. HCM may be treated with a number of drugs. There currently is no evidence that any drug alters the natural history of hypertrophic cardiomyopathy (HCM) in cats until they are in heart failure. Diltiazem, atenolol, ACE inhibitors and, possibly, spironolactone are commonly administered by veterinarians to cats with mild to severe HCM that are not in heart failure on an empirical basis in the hope that they will slow the progression of the disease. Once the cat is in heart failure, other medications may be given including drugs such as plavix to reduce risk of embolism. Treatment is rather frustrating and may be disappointing.
Dilated cardiomyopathy (DCM) is less common in cats now. DCM occurs when the heart muscle thins out and the chamber enlarges. The heart is not able to pump the blood forward because the muscle is weak. Fluid accumulates in the lungs and abdomen and causes congestive heart failure. DCM is associated with low taurine levels. Taurine is supplemented in all commercial foods now so DCM is relatively uncommon. However if your cat is on a homemade diet you need to supplement taurine to prevent this problem.
Restrictive cardiomyopathy (RCM) is the third type of heart disease in cats. It is not common and is difficult to diagnose. Prognosis for this type of heart disease is poor.
From a natural stand point, there are many ways to treat these feline heart problems. Traditional Chinese Veterinary Medicine with herbs and acupuncture can be helpful. Chinese herbs such as Dan Shen and Gingko may be used but this requires a diagnosis by a practitioner as each case is different. Homeopathy and homotoxicology has been helpful along with conventional medication for those kitties in heart failure. Omega 3 fatty acids (fish oil) is always a good and safe choice. Pet Wellbeing has a new herbal medication called Young At Heart (Link is here: http://bit.ly/HI65Iw). This herbal combination has Hawthorne in it which has been proven to help people and animals with heart disease. I have used it in my patients when other conventional medications have failed and had good results. Be sure to discuss any herbal product that you give to your pet with your primary veterinarian.