Home Heart Disease Enlarged Heart (Cardiomegaly)

What Causes an Enlarged Heart?

An orange circle with a red heart and magnifying glass as a metaphor for an enlarged heart


Cardiomegaly or an enlarged heart occurs when the heart is bigger than the normal. The heart is a muscular pump that is usually around the size of a clenched fist. The heart can become enlarged if the chambers widen or if the muscle works hard that it thickens.

An enlarged heart isn’t a condition but rather a symptom of a heart condition or defect that makes the heart work harder. It may be a symptom of high blood pressure, cardiomyopathy, or heart valve problems.

An enlarged heart cannot pump blood as effectively and as efficiently as a normal sized heart that’s why it may lead to complications such as heart failure and stroke.

An enlarged heart is frequently due to another condition that puts added stress on the heart that leads to damage of the heart although there are several possible causes for having an enlarged heart.

These are some of the causes of an enlarged heart:

  • Hypertension or high blood pressure

High blood pressure is one of the most common causes of having an enlarged heart. When an individual has hypertension or high blood pressure, the blood pumps with more effort through the arteries which strains the heart. High blood pressure can be due to a sedentary lifestyle and obesity.

  • Coronary artery disease

Coronary artery disease or ischemic heart disease is another common cause of having an enlarged heart which occurs when the fatty plaques or deposits build up inside the coronary arteries which result in narrowed arteries that prevent blood from going to the heart. It decreases the supply of oxygen that is needed as fuel for the pump.

  • Idiopathic dilated cardiomyopathy

There may be a lot of causes for having an enlarged heart but in some cases, the cause is unknown. Having a dilated or enlarged heart is a common type of cardiomyopathy.

  • Cardiomyopathy

Cardiomyopathy is a heart condition that is progressive. It has several types. Diseases that cause damage to the heart muscle can cause the heart to enlarge. The more damage that there is, the harder it is for the heart to pump.

  • Heart valve disease

Medications, infections, and connective tissue diseases can cause damage to the valves that allow blood to keep flowing in the correct direction through the heart. A damaged mitral valve allows the blood to flow backward, causing the heart chamber to work harder and contract with more force than the usual to be able to push the blood out.

  • Myocarditis

Myocarditis, also called inflammatory cardiomyopathy, is an inflammation of the heart muscle that is frequently caused by a virus infection. An individual may first experience a viral illness followed by symptoms of congestive heart failure.

  • Cardiac ischemia

Cardiac ischemia is a restriction in the supply of blood to tissues which causes a shortage of oxygen that is needed by the body for cellular metabolism. This condition can cause angina or a stabbing pain in the heart.

  • Arrhythmia or abnormal heartbeat

Arrhythmia is a condition in which the heartbeat is abnormal or irregular, meaning, it is either too slow or too fast. Most types of arrhythmia don’t have symptoms but some cases of arrhythmia present symptoms such as palpitations and feeling pause in between heartbeats.

  • Thyroid disease or disorders

The thyroid gland produces hormones that regulate the metabolic functions. Overproduction and underproduction of the hormones can cause high blood pressure, irregular heartbeat, enlargement of the heart, and high blood cholesterol l levels.

  • Pericardial effusion

Pericardial effusion or fluid around the heart is the abnormal accumulation of fluid in the pericardium where the heart is located. The accumulation of fluid results in an increased intrapericardial pressure that can badly affect the heart function and can cause the heart to appear enlarged on a chest x-ray.

  • Anemia

Anemia is a condition in which there aren’t enough healthy red blood cells produced to carry enough oxygen to the tissues of the body. Chronic anemia that is left untreated can result in an irregular heartbeat. The heart needs to pump more blood to make up for the lack of oxygen in the blood.

  • Hemochromatosis

Hemochromatosis is a condition in which there is excess iron in the body which allows it to build up in different organs in the body including the heart. It can cause an enlarged left ventricle because of the weakened heart muscle.


Congenital diseases are heart conditions that an individual is born with. Congenital diseases that can cause an enlarged heart include:

  • Coarctation or narrowing of the aorta
  • Ebstein’s anomaly or a problem with the valve separating the ventricle and the atrium
  • Atrial septal defect
  • Patent ductus arteriosus or a hole in the aorta
  • Ventricular septal defect
  • Tetralogy of Fallot or a mixture of birth defects that interrupt the normal blood flow through the heart

Other possible causes of an enlarged heart include:

  • Alcohol and drug abuse
  • Previous heart attack
  • Old age
  • Lack of exercise
  • Obesity
  • Rare diseases affecting the heart like amyloidosis
  • Pregnancy
  • HIV infection
  • Kidney disease that needs dialysis
  • Genetic conditions