A group of diseases that affect the myocardium (muscle of the heart).

There are three basic types of cardiomyopathy, which are distinguished by the kind of muscle problem involved:

• Dilated cardiomyopathy, in which the heart muscle becomes weak and the heart chambers subsequently dilate.
• Hypertrophic cardiomyopathy, in which the heart muscle itself is much thicker than normal.
• Restrictive cardiomyopathy, in which the heart becomes stiff and cannot fill efficiently during diastole, the period of the...