What Causes an Enlarged Heart — and What It May Mean for Your Health

An enlarged heart can sound alarming, especially if it’s discovered during a routine test or imaging scan. But having an enlarged heart doesn’t always mean your heart is failing — or that you’ll experience symptoms.

Also known as cardiomegaly, an enlarged heart is essentially a sign that something has caused the heart muscle or chambers to change in size. In many cases, these changes develop gradually as the heart works harder to pump blood.

Learning what causes an enlarged heart can help you recognize potential risks and know when it’s time to talk with your doctor.

What is Cardiomegaly?

Cardiomegaly refers to a heart that’s bigger than normal, either because the heart muscle has thickened or because one or more chambers have stretched or dilated. These changes can affect how well the heart pumps blood, and if it isn’t pumping blood well, blood and fluid can back up in the veins or leak into surrounding tissues. Often, the impact of this condition depends on what’s causing the enlargement and how early it’s addressed.

The Most Common Causes of an Enlarged Heart

There isn’t one single reason your heart may become enlarged. Instead, cardiomegaly usually develops as a response to another condition that puts extra strain on the heart.

Some common enlarged heart causes include:

• Cardiomyopathy: Thisrefers to diseases that affect the heart muscle itself. Some cause the heart muscle to thicken, while others cause the chambers to stretch and weaken. Hypertrophic cardiomyopathy, for example, causes the heart muscle to become abnormally thick.

• Congenital heart disease: Some people are born with a structural problem in the heart that affects how blood flows. This can cause the heart to enlarge as it adapts to different circulation patterns.

• Heart attacks and coronary artery disease: A heart attack can damage and weaken the heart muscle. When areas of the heart don’t contract as well, the remaining muscle may stretch or enlarge to compensate. Coronary artery disease, which reduces blood flow to the heart muscle, can cause similar changes over time.

• Heart valve disease: Your heart valves help blood move in the right direction through the heart. If one of your valves is narrowed or doesn’t close properly, the heart may need to pump harder to maintain blood flow. This extra effort can cause parts of the heart to enlarge, especially if the problem isn’t caught and treated early.

• High blood pressure: Long-lasting, or chronic, hypertension is one of the most common reasons the heart becomes enlarged. When blood pressure is high, the heart must work harder to move blood through the body. Over time, this can lead to left ventricular hypertrophy, a condition in which the heart’s main pumping chamber thickens. While the thicker muscle may initially help the heart pump more strongly, it can eventually become stiff and less efficient.

• Lung conditions and pulmonary hypertension: Chronic lung diseases and conditions that raise blood pressure in the lungs can affect the right side of the heart. This may lead to right atrial enlargement or enlargement of the right ventricle as the heart works harder to pump blood to the lungs.

Other Contributing Factors

In some cases, an enlarged heart may be temporary. Pregnancy, for example, can cause short-term heart enlargement that goes away after delivery.

Other contributors may include:

• Excessive alcohol use
• Infections affecting the heart
• Severe anemia
• Thyroid disorders

Finding and addressing the underlying cause of an enlarged heart is crucial to preventing its progression.

Signs of an Enlarged Heart

Some common symptoms of an enlarged heart include:

• Dizziness or chest discomfort
• Fatigue or weakness
• Heart palpitations
• Shortness of breath
• Swelling in the legs, ankles or feet

Most of the time, symptoms develop gradually, which is why routine check-ups can play a crucial role in early detection.

Diagnosing an Enlarged Heart

Often, imaging tests like a chest X-ray or echocardiogram reveal an enlarged heart. Your doctor may also use these tests, as well as a cardiac MRI, to understand which parts of the heart are affected and how well it’s working.

Additionally, you may require blood work, an electrocardiogram, or a stress test to determine the cause.

Cardiomegaly Treatment

Treatment for an enlarged heart often depends on its underlying cause. In some cases, early treatment can help prevent further enlargement and improve symptoms.

Treatment may involve:

• Lifestyle changes, such as improving your diet and physical activity levels
• Medications to lower blood pressure or reduce fluid buildup
• Ongoing monitoring for changes in heart function
• Procedures or surgery to repair your heart valves

Long-Term Care for an Enlarged Heart

An enlarged heart doesn’t define your future. With the right care and support, most people can live well with the condition. Staying on top of your blood pressure, managing chronic conditions and keeping up with appointments with your care team can make a meaningful difference. Paying attention to new or worsening symptoms and seeking care early can also help protect your quality of life.

Expert Care for Complex Heart Conditions

If you’ve been diagnosed with an enlarged heart or have concerning symptoms or risk factors, specialized care matters.

At AdventHealth, our heart and vascular experts work together to identify the underlying causes of heart changes and develop personalized treatment plans that support your health at every stage.

With advanced diagnostics, advanced treatment options and a focus on caring for the whole person — body, mind and spirit — we’re here to help you move forward with confidence.

Learn more about heart and vascular care at AdventHealth.