The most common kind of cardiomyopathy in children is dilated cardiomyopathy. Viral infections (viruses) are a common cause. These infections can irritate the heart muscle (a condition called myocarditis) and weaken it. To try keeping up with the body’s need for blood and oxygen, the heart works harder and gets bigger.
Other forms of dilated cardiomyopathy are genetic, meaning it can be passed down from parents to children in their genes and runs in families. Sometimes, no cause can be identified. Doctors call this “idiopathic” dilated cardiomyopathy.
Hypertrophic cardiomyopathy is usually caused by a problem with 1 or more genes that are involved with heart muscle development. Some babies born with this type of cardiomyopathy show signs of an abnormal heart at birth, but in many people, it is not diagnosed until later in life. Hypertrophic cardiomyopathy can also develop after birth because of some other health problem, such as acromegaly (a hormone problem that causes excess growth).
Restrictive cardiomyopathy is the least common kind. It is rare in children and is sometimes associated with a gene problem, but often no cause is identified. The condition can occur in babies born with an unusually thick lining in their heart. It can also develop in children if another condition causes scar tissue or some other kind of cell to build up in their heart muscle. One example would be a tumor that invades the heart.