What Is It, Causes, Treatment, and More

Author: Ashley Mauldin, MSN, APRN, FNP-BC

Editors: Alyssa Haag, Ian Mannarino, MD, MBA

Illustrator: Jillian Dunbar

Copyeditor: Joy Mapes

Modified: 28 Dec 2023

What is cardiomegaly?

Cardiomegaly refers to the enlargement of the heart and is usually indicative of an underlying heart condition

The heart, which is located in the center of the chest, is responsible for pumping blood throughout the body. It is made up of two atria, the chambers at the top, and two ventricles, the bottom chambers. The septum, a dividing wall of tissue, separates the heart into left and right halves. With cardiomegaly, enlargement of the heart can include the entire heart, one side of the heart (i.e., the right or left), or a specific area (i.e., the atria or ventricles). 

What causes cardiomegaly?

Cardiomegaly can develop from a variety of conditions that affect how the heart functions. Certain conditions, such as high blood pressure, can make the heart work harder to pump blood throughout the body. On the other hand, conditions like coronary artery disease and cardiomyopathy can lead to damage of the heart muscle. Regardless, all of these conditions can reduce the heart’s ability to pump blood efficiently and consequently cause the heart muscle to enlarge, resulting in cardiomegaly.  

In the case of high blood pressure, the heart muscle enlarges because the heart muscle must work harder so it can overcome the higher pressure and keep pushing blood throughout the body. Similarly, pulmonary hypertension, which occurs when there is increased pressure in the pulmonary artery that connects the right side of the heart to the lungs, can also force the heart to pump harder in order to push blood forward, through the lungs, and into the left side of the heart. As a result of the increased exertion, the right side of the heart may enlarge. 

Coronary artery disease, which results from the build up of fat deposits (i.e., plaque) in the arteries of the heart, can block some blood flow to the heart and subsequently damage or kill parts of the heart muscle. In order to compensate for the damaged muscle, the rest of the heart muscle will enlarge so it can continue pumping blood throughout the body.

Cardiomyopathy, a group of heart conditions that directly affect the heart muscle, also lead to cardiomegaly. The most common types of cardiomyopathy are dilated, restrictive, and hypertrophic cardiomyopathy. In addition, pericarditis, or inflammation of the heart’s pericardium (i.e., the fibrous sac surrounding the heart), can make the heart enlarge. 

Moreover, conditions that do not directly affect the heart can also lead to cardiomegaly. Anemia, which is characterized by low red blood cell counts, may require the heart to pump harder in order to circulate enough oxygen throughout the body. An underactive thyroid (i.e., hypothyroidism) or an overactive thyroid (i.e., hyperthyroidism) can change the heart rate and blood pressure in ways that enlarge the heart. Additionally, excessive iron in the body, or hemochromatosis, can cause cardiomegaly as a result of iron deposition and accumulation in the heart. 

Other risk factors for the development of cardiomegaly include heart valve disease, congenital heart conditions (i.e., heart conditions that are present at birth), rare diseases (e.g., amyloidosis), and having a family history of cardiomegaly. Cardiomegaly can also result from conditions that cause short-term stress on the body, including pregnancy. 

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What are the signs and symptoms of cardiomegaly?

People who have an enlarged heart usually show signs or symptoms that may include shortness of breath, abnormal heart rhythms, fatigue, chest pain, and swollen feet.

How is cardiomegaly diagnosed?

To diagnose cardiomegaly, a healthcare provider will start by reviewing the individual’s medical history and performing a physical exam. A chest X-ray is often conducted in order to visualize enlargement of the heart. Once cardiomegaly has been confirmed, additional tests will be performed to determine the cause of the enlargement. These tests can include an electrocardiogram, which looks at the electrical activity of your heart; an echocardiogram, which measures how effectively the heart is able to pump blood; and cardiac magnetic resonance imaging (MRI), which can assess the size and shape of the heart. Blood tests (e.g., complete blood count, complete metabolic panel, brain natriuretic peptide test, troponin test) may also be recommended to help determine the underlying cause.

How is cardiomegaly treated?

Treatment of cardiomegaly often begins with lifestyle modifications to decrease risk factors. These may include losing weight, increasing exercise, decreasing alcohol consumption, and eating a variety of fruits, vegetables, whole grains, nuts, poultry, and fish, while limiting intake of sodium, red meats, and saturated fats. 

Beyond lifestyle modifications, treatment often involves medication to address the underlying cause. In cases of coronary artery disease, medication may be prescribed to reduce cholesterol levels in the body (e.g., statins, niacin) and keep blood flowing through the arteries (e.g., aspirin). Other prescription medications, like angiotensin-converting enzyme (ACE) inhibitors, can help regulate high blood pressure. Hypertrophic cardiomyopathy treatment usually consists of medications (e.g., beta blockers, calcium channel blockers) that work to relax the heart so it can pump blood more effectively.

If left untreated, cardiomegaly can lead to the development of blood clots and heart failure. Cardiomegaly can be life-threatening, so diagnosis and treatment by health care professionals are critical.

What are the most important facts to know about cardiomegaly?

Cardiomegaly refers to the enlargement of the heart. Cardiomegaly isn’t a disease itself, but is rather a change in the heart muscle as a result of an underlying heart condition. These conditions either make the heart work harder to pump blood throughout the body or damage the heart muscle, so the heart enlarges to compensate for the extra exertion. Coronary artery disease, high blood pressure, cardiomyopathy, pulmonary hypertension, pericarditis, anemia, thyroid disease, hemochromatosis, heart valve disease, congenital heart conditions, pregnancy, and a family history of cardiomegaly can all lead to development of cardiomegaly. People who have an enlarged heart usually show signs or symptoms that may include shortness of breath, abnormal heart rhythms, fatigue, chest pain, and swollen feet. Treatment of cardiomegaly often involves lifestyle changes to reduce risk factors and medication to treat the underlying cause. If the cause of cardiomegaly is left untreated, blood clots, cardiac arrest, heart failure, and death can occur. 

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Related links

ACE inhibitors, ARBs, and direct renin inhibitors
Anatomy of the heart
Cardiac muscle histology
Lipid-lowering medications: Statins

Resources for research and reference

American Heart Association. (2017, August 15). The American Heart Association diet and lifestyle recommendations. [Online]. Available from: Accessed March 31, 2021.

American Heart Association. (n.d.). How the healthy heart works. In American Heart Association: Health topics; Congenital heart defects. [Online]. Available from: Accessed March 15, 2021.

American Heart Association. (2017, May 31). What is heart failure? In American Heart Association: Health topics; Heart failure. [Online]. Available from: Accessed March 20, 2021.

Cedars Sinai. (n.d.). Restrictive cardiomyopathy. In Cedars Sinai: Health library; Conditions & treatments. [Online]. Available from: Accessed April 6, 2021.

Cleveland Clinic. (n.d.). Hypertrophic cardiomyopathy. In Cleveland Clinic: Health library; Disease & conditions. [Online]. Available from: Accessed March 20, 2021.

Dignity Health. (n.d.). Diagnose your cardiomegaly with an expert at dignity health. [Online]. Available from: Accessed March 19, 2021.

Felker GM, Thompson RE, Hare JM, et al. Underlying causes and long-term survival in patients with initially unexplained cardiomyopathy. N Engl J Med. 2000;342(15):1077-1084. doi:10.1056/NEJM200004133421502

Sethi T, Singh AP, Singla V, Singh Y. Biatrial enlargement: an unusual cause of massive cardiomegaly. BMJ Case Rep. 2013;2013:bcr2012008320. Published 2013 Jan 31. doi:10.1136/bcr-2012-008320