“An enlarged heart (cardiomegaly) isn’t a disease, but rather a sign of another condition.

The term “cardiomegaly” refers to an enlarged heart seen on any imaging test, including a chest X-ray. Other tests are then needed to diagnose the condition that’s causing the enlarged heart.

An enlarged heart (cardiomegaly) can be caused by damage to the heart muscle or any condition that makes the heart pump harder than usual, including pregnancy. Sometimes the heart gets larger and becomes weak for unknown reasons. This condition is called idiopathic cardiomyopathy.”

MAYO CLINIC (Enlarged heart – Symptoms & causes – Mayo Clinic)