Hypertrophic cardiomyopathy (HCM) is a complex cardiac disease marked by thickening of the heart muscle. In HCM patients this thickening occurs for no apparent clinical cause like significant high blood pressure. The disease doesn't affect everyone the same way, with different degrees of muscular wall thickening and a variety of symptoms. Patients may have shortness of breath, exercise intolerance, chest pressure or pain, fainting, or no symptoms at all. In unusual cases HCM can cause sudden cardiac death. The diagnosis of HCM is usually made with echocardiography, a cardiac ultrasound examination. Among the many variations that can occur in HCM, some patients are found to have obstruction while others are non-obstructed. Patients in both groups have heart thickening and both can have troubling symptoms. Patients with obstruction have a blockage inside the heart that results in the heart overworking as it pumps blood to the body. Obstructive HCM used to be called idiopathic hypertrophic subaortic stenosis (IHSS). In patients without obstruction the thickening of the heart itself results in the symptoms. Why do patients seek evaluation and treatment for HCM? Some patients seek relief of symptoms. Others come because they have risk factors for sudden cardiac death such as blackouts or sudden deaths in the family. Occasionally patients seek confirmation of a diagnosis of HCM. For example, it is sometimes difficult to differentiate HCM from the athlete's heart syndrome, a mild thickening of the heart due to exercise conditioning. Because HCM is often inherited, family members may carry a gene for the disease even if they have no symptoms. All parents, children, brothers and sisters of anyone with HCM should be screened. In HCM patients, it is thought that the walls of the heart thicken because of a genetic abnormality of the heart muscle. To learn more about HCM contact the Hypertrophic Cardiomyopathy Association, a national educational organization for HCM patients. Another contact is the Hypertrophic Cardiomyopathy Research Foundation website. HCM Diagnosis HCM Treatment   If you have any questions or concerns about this site, please contact webmaster@hcmny.org.