Having an enlarged heart may have serious consequences.

Unlike the metaphorical big heart, having an actual enlarged heart may not be such good news. Although it’s not a disease in itself, it could point to an underlying heart problem.

An enlarged heart is sometimes only discovered during a routine x-ray. Up until then the patient may not have experienced any symptoms. This is why most of the time, people who have it are not even aware they do.

“When it’s discovered, we will usually investigate further to identify the root cause,” said Dr Tang Hak Chiaw, Senior Consultant, Department of Cardiology, National Heart Centre Singapore (NHCS ).

What causes the swell?

The heart enlarges for various reasons. The most common cause is coronary artery disease, in which cholesterol buildup narrows the arteries which supply blood to the heart. When this happens, the person is at a higher risk of having a heart attack, which can damage the heart muscle and weaken its function. In addition, insufficient blood supply to the heart muscle itself also weakens it.

A weakened heart muscle means the heart is unable to pump the full volume of blood to the rest of the body. It tries to make up for this by becoming bigger.

“A large proportion of heart failure patients have enlarged hearts. They come to us with breathlessness, chest pain, leg swelling or abdominal bloating, which are typical symptoms of heart failure. Further tests reveal an enlarged heart,” said Dr Tang.

He said enlargement is a compensatory mechanism of the body. “Theoretically, a larger heart pumps better, but beyond a certain stage, the heart will fail.”

Left untreated, patients may have to live with symptoms of heart failure – being always breathless, on long-term medication, and frequently hospitalised for water retention.

 Infections, genetic diseases, alcohol or drug abuse, and chemotherapy can damage the heart muscle, too.

Other causes of heart weakening are conditions that make the heart overwork, such as uncontrolled high blood pressure, leaky or malfunctioning heart valves, and thyroid disease.

Treating the root cause

Dr Tang said that the best way to manage an enlarged heart is to treat the underlying disease.

Patients with coronary artery disease may be put on medication or have a stent put in, to open up their narrowed arteries. Medication can also lower uncontrolled high blood pressure. But whether a heart reverts to its original size after treatment depends on how much damage it has already sustained.

Sometimes, total reversal of the enlargement is possible. “For example, a leaky valve can be fixed by surgery.

We will usually monitor the heart’s size and beyond a certain size, we will advise surgery to fix the leakage. If intervention occurs at the correct time, the enlarged heart can be totally reversed,” said Dr Tang.

However, not all underlying causes can be treated. Nothing much can be done if the heart muscle is severely damaged due to genetic diseases or a heart attack. In such cases, patients are given medication to prevent further enlargement. If that fails, a heart transplant may be needed. 

Prevention is best

Dr Tang said that patients can play a part too. “If [a patient] has high blood pressure, he needs to keep it in check by taking his medication regularly and according to the prescribed dosage. If not, his heart will weaken and he may end up with heart failure.”

He encourages patients to maintain a healthy lifestyle with a well-balanced diet and regular exercise. Those with risk factors such as a family history of coronary artery disease should get themselves screened, so that it can be caught before it leads to heart failure.

Having an enlarged heart is not always a cause for concern though. For instance, the heart of an avid runner or cyclist works harder to pump more blood, and hence, oxygen, to the rest of the body.

“At rest, the heart pumps about four to five litres of blood in a minute. But when running or cycling it can go up to 20-30 litres a minute. So, in a person who does this fairly regularly, the heart adapts by becoming larger to manage this capacity. This is entirely reversible in most of these athletes’ hearts,” said Dr Tang.


NHCS is currently doing a real-time study of exercise using cardiovascular magnetic resonance to accurately diagnose whether an enlarged heart is due to a person’s active lifestyle or underlying heart conditions. It is looking for healthy volunteers for stage 1 of the study (stage 2 will come later, and will involve patients with heart conditions). Healthy volunteers who wish to take part in stage 1 can call 8131 8488 or email mribike@ nhcs.com.sg for more information.