Cardiomegaly means that your heart is larger than normal. Often, it is a term used to describe the heart’s appearance on a chest X-ray.
There are several reasons your heart can appear to be large:
- the main pumping chamber, the left ventricle, has become dilated over time, because the heart muscle is weak (dilated cardiomyopathy)
- the heart muscle has become thick (hypertrophy) because it is pumping against a high blood pressure
- there is fluid around the heart (pericardial effusion), making the heart shadow appear big (but it’s just the fluid around the heart, not the heart itself)


If the heart appears to be large on the chest X-ray, then a transthoracic echocardiogram is often the next best test to look at the heart size, structure, and function to see if there is a problem.
Cardiomegaly is not a disease or condition; it’s just a description that tells you the heart appears large. It is important that a cause for cardiomegaly is found and investigated, so that a treatment can started if necessary.