Cardiomegaly (Enlarged Heart)

What cardiomegaly means

On a standard chest X-ray, the heart's width is compared with the width of the chest. A cardiothoracic ratio greater than 0.5 (the heart takes up more than half the chest width) is reported as cardiomegaly. X-rays can overestimate heart size, for example in a portable X-ray taken from the front, a shallow breath, or extra fat or fluid around the heart. So "mild cardiomegaly" on an X-ray always needs an echocardiogram (ultrasound of the heart) to confirm it.

The heart enlarges in two main ways:

A pericardial effusion (fluid collecting in the sac around the heart) can make the heart look enlarged on an X-ray even when the heart itself is normal.

Causes of an enlarged heart

• High blood pressure: the most common cause. Pumping against high pressure for years thickens the left ventricle.
• Coronary artery disease and heart attacks: damaged muscle stretches and the remaining muscle works harder.
• Cardiomyopathy: diseases of the heart muscle, including inherited dilated and hypertrophic types.
• Heart valve disease: a narrowed valve such as aortic stenosis causes thickening. Leaky valves cause stretching.
• Arrhythmias: a persistently fast rhythm, including poorly controlled atrial fibrillation, can weaken and enlarge the heart.
• Pulmonary hypertension: high pressure in the lung arteries enlarges the right side of the heart.
• Severe anemia, an overactive thyroid and kidney disease: these make the heart pump more blood.
• Alcohol, cocaine and some chemotherapy drugs: these can damage the heart muscle directly.
• Pregnancy: peripartum cardiomyopathy develops in late pregnancy or soon after birth.
• Athletic training: endurance athletes develop a mildly enlarged, healthy "athlete's heart". A cardiologist can usually tell this apart from disease.

Symptoms

Many people have no symptoms, especially early on. When the enlarged heart cannot pump well, the symptoms are those of heart failure:

• Shortness of breath on exertion, then at rest or when lying flat
• Waking at night breathless
• Swelling of the ankles and legs, or the belly
• Tiredness and reduced exercise ability
• Palpitations or an irregular heartbeat
• Dizziness or fainting
• Rapid weight gain from fluid

How doctors investigate it

1. History and examination: blood pressure, heart murmurs, swelling, family history, alcohol and drug use.
2. Echocardiogram: the key test. It measures chamber size, wall thickness, pumping strength (ejection fraction) and valves.
3. Electrocardiogram (ECG): shows rhythm problems, thickened muscle and signs of past heart attacks.
4. Blood tests: BNP or NT-proBNP (raised in heart strain), blood count, thyroid, kidney function and iron.
5. Further tests as needed: cardiac MRI to look for scarring or inflammation, a coronary angiogram or CT to check for blocked arteries, a Holter monitor, and genetic testing if cardiomyopathy runs in the family.

Treatment

Treatment depends on the cause:

• Blood pressure control with medicine and less salt.
• Heart failure medicines when the ejection fraction is reduced. Combinations of ACE inhibitors or ARNIs, beta-blockers, mineralocorticoid antagonists and SGLT2 inhibitors improve survival and can make the heart smaller. Diuretics relieve fluid build-up.
• Valve repair or replacement for significant valve disease.
• Treating the rhythm: rate or rhythm control for atrial fibrillation.
• Revascularization with stents or bypass surgery for blocked coronary arteries.
• Devices: an implantable defibrillator (ICD) for people at high risk of dangerous rhythms, or a biventricular pacemaker to coordinate the heart's pumping.
• Stopping alcohol or drugs that damage the heart.

Home measures

• Weigh yourself every morning and report sudden gains.
• Limit salt, and fluids if advised.
• Take medicines exactly as prescribed and avoid NSAIDs such as ibuprofen unless your doctor agrees, because they cause fluid retention and worsen heart failure.
• Stay active with an exercise plan approved by your care team, or join cardiac rehabilitation.

Complications

• Heart failure
• Blood clots in the enlarged chambers, which can cause a stroke
• Leaky heart valves as the valve ring stretches
• Dangerous heart rhythms and sudden cardiac arrest

Outlook

The outlook depends on the cause and how well the heart pumps. Enlargement from high blood pressure, a fast rhythm, alcohol, pregnancy or thyroid disease often improves once the cause is treated. Modern heart failure medicines can partly reverse enlargement, a process called reverse remodeling. Inherited cardiomyopathies need lifelong follow-up, and close relatives should be screened.

Frequently asked questions

Is cardiomegaly serious?

It can be, because it shows the heart has been under strain. But how serious depends on the cause and how well the heart pumps. Mild enlargement from high blood pressure with a normal pump is very different from a large, weak heart. An echocardiogram answers this.

Can an enlarged heart go back to normal?

Sometimes. When the cause is treatable, such as high blood pressure, a fast heart rhythm, alcohol, thyroid disease or pregnancy, the heart can shrink partly or fully. Heart failure medicines can also reverse some enlargement. Long-standing damage from heart attacks usually does not fully reverse.

What does mild cardiomegaly on a chest X-ray mean?

It means the heart's outline looks slightly wider than half the chest. It may be a real enlargement or an effect of how the X-ray was taken. Your doctor will usually arrange an echocardiogram to measure the heart accurately.

What are the symptoms of an enlarged heart?

Many people have none. When symptoms appear, they include breathlessness, swollen ankles, tiredness, palpitations, dizziness and fast weight gain from fluid. These reflect heart failure or rhythm problems caused by the enlarged heart.

Can you live a long life with an enlarged heart?

Many people do, especially when the cause is found early and treated, and when they take heart failure medicines and attend follow-up. The outlook is worse with a very weak pump or untreated cause.