What Causes an Enlarged Heart?

An enlarged heart, medically known as cardiomegaly, occurs when parts of the heart thicken or become too big. In some cases, people are born with this condition, but heart disease, diabetes, and pregnancy can also raise the risk. Common causes of an enlarged heart include coronary artery disease and abnormal heart rhythms.

Coronary Artery Disease

Coronary artery disease (CAD) occurs when the heart's arteries (blood vessels) narrow and can't supply enough oxygen-rich blood to the heart. This condition affects the large coronary arteries on the heart's surface.

The most common cause of CAD is a buildup of cholesterol, a waxy substance, inside the artery walls. This can cause plaque to form in your arteries and partially or completely block blood flow in the heart's large arteries, which may enlarge your heart and raise your risk of a heart attack and heart failure.

Valvular Heart Disease

The heart has four valves, and any of them can become damaged or infected. This is called valvular heart disease. Normally, heart valves open and close to control blood flow in and out of the heart. When a valve becomes diseased or damaged, it will not close properly. This causes blood to flow in a backward motion, makes it harder for your heart to pump blood, and enlarges your heart.

Congenital Heart Defects

Sometimes, people are born with heart conditions, which are known as congenital heart defects. One example is an atrial septal defect, which occurs when a hole in the wall separates the heart's upper chambers (atria). Another example is a ventricular septal defect, where a hole in the wall separates the heart's lower chambers (ventricles).

There are nearly 20 known types of congenital heart defects, all of which can cause your heart to become larger in size.

Cardiomyopathy

Cardiomyopathy is a heart muscle disease that makes it harder for the heart to pump blood to the rest of the body. There are different types of cardiomyopathy, like hypertrophic cardiomyopathy, which causes the heart muscle to become too thick and large. Over time, the heart becomes weaker and less able to pump blood effectively, which can lead to heart failure or arrhythmias.

Abnormal Heart Rhythm (Arrhythmia)

Abnormal heart rhythms (also known as arrhythmias) occur when the heart doesn't beat as it should. Certain heart rhythm problems, such as atrial fibrillation (AFib) and atrial flutter, can lead to an enlarged heart.

In atrial fibrillation, the heart’s upper chambers beat rapidly and irregularly. This causes the heart to not fill with blood completely in between beats. An atrial flutter also causes your heart's upper chambers to beat too rapidly, but the beating is organized and regular.

Lung Diseases

Certain lung diseases like pulmonary hypertension, chronic obstructive pulmonary disease (COPD), and pulmonary embolism can all cause an enlarged heart.

Pulmonary hypertension happens when the blood pressure in the lung’s arteries is too high, COPD occurs when your airways become too narrow and cause trouble breathing, and pulmonary embolisms develop when a blood clot is stuck in the lung.

Is an Enlarged Heart Hereditary?

An enlarged heart can sometimes be linked to your genes.

Familial dilated cardiomyopathy is a type of genetic heart disease that can get passed down from parents to children. In this condition, the heart muscle becomes thin and weak in at least one of its chambers, causing it to become bigger. This causes your heart to have difficulty pumping blood effectively. In response, the heart tries to pump more blood, which leads to further thinning and weakening of the heart muscle. Over time, this condition can result in heart failure.

More than 30 genes have been linked to familial dilated cardiomyopathy. These genes help make proteins in heart muscle cells. However, more research is needed to understand the genetic mutations in these genes and why they may be causing an enlarged heart.

Who Gets an Enlarged Heart?

Anyone can develop an enlarged heart. A person can be born with an enlarged heart or develop the condition later in life. As people get older, the heart may also increase in size. This is usually due to the heart working harder over the years to pump blood. These changes can be a normal part of aging but can also be influenced by other risk factors such as hypertension (high blood pressure) and heart disease.

Risk Factors 

While having a family history of heart disease or an enlarged heart can increase your risk of having too large of a heart, certain underlying health conditions can also raise your chances of developing the condition.

Diabetes

Diabetes, which causes high blood sugar levels due to an inability to respond to insulin properly, is a common risk factor for heart disease. High blood sugar can harm your blood vessels and the nerves that control your heart. As you age, this can affect the functioning of your heart. People with diabetes also have a higher chance of developing heart disease compared to those who don't live with diabetes.

Uncontrolled High Blood Pressure

High blood pressure can raise your risk of heart disease and stroke. If you don't receive proper treatment and make healthy lifestyle changes, uncontrolled high blood pressure can make it difficult for your heart to pump blood. As the condition worsens, your heart muscle can become too thick and large, especially in the left ventricle.

Sarcoidosis and Amyloidosis

Sarcoidosis is a rare inflammatory disease in which the immune system overreacts, causing clusters of inflamed tissue to form in an organ. It typically affects the lungs and lymph nodes but can also affect the heart.

Amyloidosis is a condition that causes a buildup of toxic protein in your organs and tissue. These protein fibers can build up in the heart and cause heart disease. Both of these conditions can raise your risk of developing an enlarged heart.

Pregnancy

Peripartum cardiomyopathy or postpartum cardiomyopathy is an uncommon form of heart failure. It occurs toward the end of pregnancy or in the months following childbirth. In this condition, the heart chambers enlarge and the heart muscle weakens. This leads to the heart becoming unable to pump as much blood as it should.

A Quick Review

Several health conditions, such as coronary artery disease and heart valve problems, can cause your heart to become too large. However, having a family history of heart disease, living with diabetes or uncontrolled high blood pressure, or going through pregnancy can also raise your risk of an enlarged heart.

If you may be at risk of an enlarged heart or one of the conditions that cause it, it's a good idea to see your healthcare provider for screening tests and treatment if needed.