Anatomical illustration of red glowing enlarged heart

What Causes an Enlarged Heart?

Medically reviewed on Feb 25, 2024 by Jordan Stachel, M.S., RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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Healthcare providers use the clinical term cardiomegaly to describe the phenomenon of having an enlarged heart. Rather than being a heart disease, cardiomegaly is a compensatory action your body takes in response to other factors—whether a preexisting illness, like heart valve disease, or lifestyle factors, like routinely engaging in high-intensity exercise. [1]

It’s important to catch cardiomegaly early, as heart enlargement can signal the existence of an underlying illness and raise your risks of heart damage and cardiac events, like congestive heart failure or blood clots. [1, 2] Treating cardiomegaly requires a thorough clinical assessment to screen for heart-related conditions so that you can target the underlying cause.

What causes an enlarged heart?

There are many causes and contributors to cardiomegaly. Below, we’ll explore them, as well as diagnostic and treatment options.

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Causes and Contributors to Cardiomegaly (Enlarged Heart)

The best way to understand cardiomegaly is that it is a sign that your heart is under too much strain or stress. [3] Because cardiomegaly is not itself an illness or a heart disease, it’s often caused by another diagnosable underlying health condition. Common causes include [1]:

  • Coronary artery disease (CAD) – Approximately 18 million American adults have CAD, considered the most common precursor to cardiomegaly. [3] CAD results in the accumulation of plaque and other substances in the arteries, inhibiting blood flow and circulation. [4] Later, CAD can lead to congestive heart failure, a progressive condition that can have both immediate and long-term consequences for the heart and for your overall health. [4]
  • Hypertension (high blood pressure) – Chronic high blood pressure can cause the heart to work harder to circulate blood. Over time, overexertion can cause the heart muscle to thicken and swell.
  • Heart valve disease – Problems with the valves of your heart can alter how blood flows in and out of your heart. Sometimes, this can cause the heart to swell to compensate for those irregularities.
  • Cardiomyopathy – Several types of cardiomyopathy affect different parts of the heart. Cardiomyopathy can cause the heart to become thicker or more rigid, leading to enlargement and making it more difficult to do its job properly.
  • Heart attack – Many people who’ve had heart attacks sustain structural damage to their heart muscle. Sometimes, scar tissue can form, causing the heart to get bigger or swell.
  • Anemia – People with anemia have fewer red blood cells to bring oxygen to the rest of the body. In response, the heart may work harder to pump available blood, leading to inflammation and heart enlargement.
  • Hemochromatosis – People who absorb too much iron from their food have a condition known as hemochromatosis. [5] Sometimes, your body can store excess iron in the heart, causing swelling (especially in the heart’s left chamber). [1]
  • Thyroid conditions – Both underactive and overactive thyroid function can be connected to heart enlargement. [6] While an underactive thyroid can reduce your heart rate and raise blood pressure, a hyperactive thyroid can cause the heart to work harder. [6] In both cases, the heart may swell to compensate for the disruption. [6] Learn how to improve your resting heart rate for better heart health.

In addition to related illnesses, lifestyle or anatomical factors can also contribute to cardiomegaly [1]:

  • High-intensity athletic training – Athletes and highly active people may develop mild cardiomegaly. However, this form of heart enlargement isn’t usually pathological and may not require medical treatment. [1]
  • Substance abuse – People who use alcohol or other substances in excess are at a heightened risk of developing cardiomegaly. [3] Tobacco use is also associated with cardiomegaly. [3]
  • Pericardial effusion (fluid buildup) – Your heart has a sac surrounding it known as the pericardium. Fluid can gather inside it, putting pressure on your heart and causing it to swell. [7]
  • Pericardial fat – Some people, especially people with obesity, can develop deposits of fat surrounding the heart, in the pericardium. [8] This can cause cardiomegaly, as well as a stiffening of the heart muscle and, in severe cases, heart failure. [8]
  • Congenital heart defects – Being born with a genetic heart condition can impair the heart’s structural and functional integrity. Cardiomegaly and a weakening of the heart can be complications.

Cardiomegaly Symptoms and Complications

Symptoms of cardiomegaly vary, as they’re often associated with the illness causing the heart to enlarge. However, many people with cardiomegaly report [3]:

  • Feeling faint or dizzy
  • Fatigue or persistent exhaustion
  • Fluid retention or swelling in the legs, feet, or stomach (edema)
  • Sensations of heart fluttering, skipping, or [heart palpitations at night](https://www.everlywell.com/blog/heart-health/heart-palpitations-at-night/)

Shortness of breath, feeling winded from physical activity, or chest pain may also arise with cardiomegaly. [4] Shortness of breath, in particular, is a common symptom of many of cardiomegaly’s underlying causes, like coronary artery disease and hypertension. [4, 9]

How is Cardiomegaly Diagnosed?

To be diagnosed with cardiomegaly, the width of your heart (called the transverse diameter) must measure at least 50% of the width of your chest. [2] Clinically, this is called an increased cardiothoracic ratio. [2]

This measurement is primarily taken using two imaging technologies [2]:

  • Radiographs
  • Computed tomography

If a healthcare provider confirms cardiomegaly, they may use other examination tools to determine which parts of your heart are enlarged. [2] Where your heart is swollen can indicate important information about possible underlying causes of your condition. [2] You may also receive blood tests, chest X-rays, and electrocardiograms to evaluate your heart’s electrical activity.

In addition to a physical examination, healthcare providers will likely take a comprehensive medical history to determine your risk of cardiomegaly and other possible cardiovascular conditions.

You may be at higher risk of an enlarged heart if [2]:

  • You’ve already been diagnosed with one of the four stages of heart failure [2]
  • You’re an older adult [2]
  • You’re African American [2]
  • You’re biologically male, as people assigned male at birth (AMAB) are at higher risk of cardiomegaly than people assigned female at birth (AFAB) [2]

Is Cardiomegaly Treatable?

Cardiomegaly is considered treatable, but determining the root cause of heart enlargement is critical for establishing the most effective healing regimen. Depending on your healthcare provider’s assessment, the following interventions may be recommended to help improve your heart health and overall well-being.

Medication

Various medications can help with the conditions spurring heart enlargement. These include [10]:

  • Angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) – These two drugs were designed to treat hypertension by reducing blood pressure and helping your heart work better. Both medicines work by helping your veins relax and widen to improve blood flow and relieve some of the pressure. [11, 12]
  • Diuretics – Diuretics are also intended to treat hypertension. They work by lowering the amount of salt (sodium) in your body to bring blood pressure down to normal levels.
  • Blood thinners – People with cardiomegaly are considered at a higher risk of heart attack, stroke, or other cardiac events. [1] Anticoagulants, or blood thinners, can help lower blood clot risk and chances of stroke or heart attack. [1]
  • Antiarrhythmics – People with cardiomegaly and other heart conditions may have irregularities in their heart’s electrical function. [13] Antiarrhythmic medicines work against these irregularities by moderating your abnormal heart rhythm. [1]

Implants and Surgery

In more serious cases of cardiomegaly, patients may need more invasive strategies to correct heart dysfunction.

When your heartbeat is irregular, healthcare providers may recommend [1]:

  • Pacemakers, which are implanted near the neck. These send electrical signals to the heart if it stops or slows, helping it to achieve a steadier pace.
  • Implantable cardioverter-defibrillators (ICDs), which are used in more serious cases to regulate your heart’s rhythm. ICDs conduct electricity directly through your veins and heart to steady your heart rate.

LVADs, or left ventricular assist devices, may be used if you have heart failure and your heart is too weak to pump blood properly. [10]

Surgery is another option for more serious cases of cardiovascular disease if implantable devices are insufficient to support heart health. Your healthcare provider may suggest [10]:

  • Heart valve surgery, if you’ve been diagnosed with heart valve disease
  • Coronary bypass surgery, if your cardiomegaly has been caused by a heart or arterial congestion

Heart transplants are a last resort treatment for people whose heart enlargement has been caused by serious and potentially fatal cardiovascular illness. Taking care of your heart health early through careful monitoring, lifestyle adjustments, and, if necessary, medication can help limit your chances of needing a heart transplant.

Lifestyle Adjustments

In most cases of cardiovascular illness, changing your lifestyle habits can greatly support the efficacy of your other treatments. It’s commonly recommended that people with cardiomegaly and other like-heart conditions [10]:

  • Limit their sodium and saturated fat intake
  • Incorporate daily exercise
  • Quit smoking (if applicable)
  • Quit or limit caffeine, alcohol, or other drug use (if applicable)
  • Control chronic stress and anxiety (if applicable)
  • Limit or eliminate excessive aerobic exercise

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References

  1. Enlarged heart - Symptoms & causes - Mayo Clinic. Mayo Clinic. Published May 4, 2022. Medical Citation URL. Accessed February 2, 2024.
  2. Amin H. Cardiomegaly. StatPearls - NCBI Bookshelf. Published November 20, 2022. Medical Citation URL. Accessed February 2, 2024.
  3. Professional CCM. Enlarged heart (Cardiomegaly). Cleveland Clinic. Last reviewed July 10, 2022. Medical Citation URL. Accessed February 2, 2024.
  4. Professional CCM. Coronary artery disease. Cleveland Clinic. Last reviewed October 13, 2023. Medical Citation URL. Accessed February 2, 2024.
  5. Hemochromatosis - Symptoms and causes - Mayo Clinic. Mayo Clinic. Published January 6, 2023. Medical Citation URL. Accessed February 2, 2024.
  6. Harvard Health. Thyroid hormone: How it affects your heart. Harvard Health. Published August 8, 2023. Medical Citation URL. Accessed February 2, 2024.
  7. Pericardial effusion - Symptoms & causes - Mayo Clinic. Mayo Clinic. Published November 13, 2021. Medical Citation URL. Accessed February 2, 2024.
  8. Study: Extra fat around the heart is associated with an increased risk for heart failure | NHLBI, NIH. NHLBI, NIH. Published June 1, 2021. Medical Citation URL. Accessed February 2, 2024.
  9. High blood pressure (hypertension) - Symptoms & causes - Mayo Clinic. Mayo Clinic. Published September 15, 2022. Medical Citation URL. Accessed February 2, 2024.
  10. Enlarged heart - Diagnosis & treatment - Mayo Clinic. Mayo Clinic. Published May 4, 2022. Medical Citation URL. Accessed February 2, 2024.
  11. Angiotensin-converting enzyme (ACE) inhibitors. Mayo Clinic. Published August 16, 2023. Medical Citation URL. Accessed February 2, 2024.
  12. Angiotensin II receptor blockers. Mayo Clinic. Published August 4, 2023. Medical Citation URL. Accessed February 2, 2024.
  13. Professional CCM. What are Antiarrhythmics? Cleveland Clinic. Last reviewed April 28, 2022. Medical Citation URL. Accessed February 2, 2024.
Jillian Foglesong Stabile, MD, FAAFP is a board-certified Family Physician. Since completing her residency training in 2010, she’s been practicing full-scope family medicine in a rural setting. Dr. Foglesong Stabile’s practice includes caring for patients of all ages for preventative care as well as chronic disease management. She also provides prenatal care and delivers babies. Dr. Foglesong Stabile completed a teaching fellowship in 2020 and teaches the family medicine clerkship for one of her local medical schools. Dr. Foglesong Stabile’s favorite thing about family medicine is the variety of patients she sees in her clinical practice.
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