What Does Cardiomegaly Mean on a Chest X-Ray?

What it means

Cardiomegaly literally means "large heart". On a chest X-ray, the radiologist compares the width of the heart shadow with the width of the chest. If the heart shadow takes up more of the chest than expected, the report may say cardiomegaly or "enlarged cardiac silhouette".

The heart can look enlarged because the heart muscle is thicker, the chambers are stretched, or there is fluid around the heart. It can also look larger than it really is depending on how the X-ray was taken, such as when lying down or not breathing in fully. By writing this word, the radiologist is flagging the heart size for the doctor who ordered the X-ray, who will decide whether it needs looking into.

An echocardiogram (heart ultrasound) is often used to look at the heart's size and function in more detail. Cardiomegaly is different from heart failure: one describes how the heart looks on a picture, and the other describes how well the heart is working.

Where you may see it

• The findings or "Impression" section of chest X-ray reports
• Chest CT reports, sometimes as "the heart is enlarged"
• Cardiology letters and echocardiogram referrals
• Hospital discharge summaries listing chest X-ray findings