Older cats may have a thickened heart muscle due to an underlying systemic cause. In our middle aged and older cats high blood pressure, kidney disease, and hyperthyroidism are common problems that increase the workload of the heart muscle and cause secondary thickening. We always try to rule out a potential underlying cause before we make the diagnosis of hypertrophic cardiomyopathy. If your cat has another problem, the response to therapy for that primary problem usually improves and may resolve the secondary heart changes. The response to any therapy depends on the stage of disease with the best response seen when therapy is started earlier in the course of the problem.
Restrictive cardiomyopathy is another type of heart muscle disease.
This form can be a late stage of hypertrophic disease or may be a primary entity. Unfortunately, restrictive cardiomyopathy presents a much greater challenge in its treatment. These cats tend to have very large left atria and are usually at high risk for the development of a blood clot and heart failure. If your cat has experienced an increased effort or rate of respiration, he or she may have experienced an episode of heart failure. Multiple medications are typically recommended to improve this situation and try to maintain your cat's normal lifestyle and appetite.