Medically reviewed by Edward Tavel, MD, Medical Director · Last reviewed 22 August 2026
Cardiomegaly is the medical term for an enlarged heart. It is helpful to understand that cardiomegaly is usually a sign of another condition rather than a disease on its own. When the heart works harder than normal for a long time, or when the heart muscle itself is affected, the heart can enlarge in much the same way any muscle responds to sustained strain. An enlarged heart is often first noticed on imaging — sometimes on a chest X-ray, a CT scan, or an MRI performed for an unrelated reason. Many people who learn they have cardiomegaly feel well and have no idea anything has changed, because the underlying cause has been quietly present for some time.
The most common causes include long-standing high blood pressure (hypertension), heart valve problems, and cardiomyopathy, a group of conditions that affect the heart muscle directly. Coronary artery disease, certain heart rhythm disorders, anemia, and thyroid conditions can also play a role. Because cardiomegaly is a sign rather than a single illness, symptoms vary with the cause and can include shortness of breath, swelling in the legs or ankles, fatigue, or an irregular heartbeat — though many people have no symptoms at all. Evaluation usually combines a physical exam, blood pressure readings, an echocardiogram (ultrasound of the heart), an electrocardiogram, blood tests, and, when more detail is needed, cardiac MRI.
Cardiac MRI gives a detailed assessment of the heart muscle and chambers, measuring their size and how well they pump. A whole-body MRI is not a substitute for a dedicated cardiac evaluation, but it may surface an enlarged heart as an incidental finding worth discussing with a cardiologist. To learn more, see our overview of the conditions a whole-body scan can detect, read about incidental findings on an MRI, or explore the Whole Body Scan at MRI Wellness. The reassuring takeaway is that many causes of an enlarged heart are manageable once they are identified.
Frequently asked questions
Is an enlarged heart serious?
It depends entirely on the cause. Cardiomegaly is a sign that something is asking the heart to work harder. Identifying and treating the underlying cause — such as high blood pressure or a valve problem — matters most, and many causes respond well to treatment.
What causes cardiomegaly?
Common causes include long-standing high blood pressure, heart valve disease, and cardiomyopathy (a condition of the heart muscle). Coronary artery disease, irregular heart rhythms, anemia, and thyroid problems can also contribute.
Can an enlarged heart be reversed?
In some cases, yes. When the cause is treated — for example, by controlling blood pressure or repairing a valve — the heart can sometimes return toward its normal size. Outcomes vary by cause, so this is best discussed with a cardiologist.
How is an enlarged heart diagnosed?
Evaluation typically includes an echocardiogram, an electrocardiogram, blood pressure measurement, blood tests, and sometimes cardiac MRI. These tests measure the heart’s size and function and point toward the underlying cause.
Can an MRI show an enlarged heart?
Yes. Cardiac MRI precisely measures the heart’s chambers and muscle. A whole-body MRI may also reveal an enlarged heart as an incidental finding, which can then be confirmed with a focused cardiac assessment.
Sources
A whole-body MRI at MRI Wellness looks at the brain, spine, chest, abdomen and pelvis in a single session, without radiation or contrast dye. No referral is needed.
