Cardiomyopathy is a term that encompasses several different disorders of the heart muscle. The most common type is dilated cardiomyopathy. In dilated cardiomyopathy, the heart chambers dilate (stretch out and become thinner). This affects how well your heart can pump blood to the rest of your body. Over time, your heart may weaken and you can experience heart failure. Some people do not realize they have dilated cardiomyopathy until symptoms of heart failure appear.