Enlarged heart: What are the causes?

Enlarged heart (cardiomegaly) is not a disease but a sign of an underlying problem. It can have many causes, including:

• High blood pressure
• Heart valve disorders
• Weakness of the heart muscle (cardiomyopathy)
• Severe anemia
• Thyroid disorders
• Excessive iron in the body (hemochromatosis)
• Abnormal protein buildup in an organ (amyloidosis)

In some people, an enlarged heart causes no signs or symptoms. Others may experience:

• Breathing difficulties
• Shortness of breath
• Dizziness
• Abnormal heart rhythm (arrhythmia)
• Swelling (edema)

Treatment is directed at the underlying cause of enlarged heart.

Source:
http://www.mayoclinic.com/print/enlarged-heart/HQ00623/METHOD=print