What is long QT syndrome?

Long QT syndrome (LQTS) is a disorder of the heart's electrical system that can cause episodes of fast, disordered heartbeats, called arrhythmias. It is named after the pattern seen on an electrocardiogram (ECG or heart tracing).

What are the symptoms of long QT syndrome?

People with LQTS may experience fast or irregular heartbeats, fainting or seizures. If the heart beats irregularly for a long time it can cause cardiac arrest in some people, and possibly sudden death.

What causes long QT syndrome?

If you have LQTS, you may have been born with a gene that puts you at risk. Some medicines can increase your risk of an abnormal fast heart rhythm if you have this gene. LQTS may also be caused by certain medicines.

When should I see my doctor?

If you have any symptoms of LQTS such as fainting, seizures or irregular heartbeats, you should see your doctor, who can advise you on treatment. If you have a family member who has been diagnosed with LQTS, ask your GP if you need a referral to a (heart specialist).

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How is long QT syndrome diagnosed?

Long QT syndrome can be diagnosed by your doctor by doing a test called an electrocardiogram (ECG). This test measures the heart’s electrical activity. An ECG creates a graph of your heart's electrical activity. It’s a simple, safe and painless test.

Long QT syndrome is named after the distinctive pattern seen on an ECG.

If someone in your family is diagnosed with LQTS, it is important that other close family members are also checked for the condition .This could involve having an ECG or undergoing genetic testing.

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How is long QT syndrome treated?

The aim of treatment in LQTS is to prevent heart arrythmias.

Treatment may involve limiting intense physical activity, avoiding certain medicines or taking medicines to help prevent you having fast or irregular heartbeats. Some people with LQTS may also need surgery that places an implantable cardioverter defibrillator (ICD) in the chest. An ICD is a device that monitors your heart rhythm and can treat episodes of arrhythmias if they occur.

Learn more about implantable cardioverter defibrillators (ICDs).

Can long QT syndrome be prevented?

Long QT Syndrome is usually genetic and cannot be prevented. It is usually present from birth but might only be diagnosed during childhood, young adulthood or later in life.

If your doctor has diagnosed you with LQTS, you need to avoid medicines that increase your risk of an abnormal heart rhythm. Tell your doctors you have LQTS before they prescribe a medicine, and check with your pharmacist before you take a new medicine.

Complications of long QT syndrome

If LQTS is not properly controlled, it can lead to serious episodes of arrhythmias, possibly causing cardiac arrest and sometimes even death.

Resources and support

For more information about the causes, symptoms, diagnosis and management of LQTS, see the Sydney Children’s Hospital Network website.

If you or a family member has LQTS, join the Australian Genetic Heart Disease Registry, whose aim is to register every family in Australia with an inherited heart disease.

Call healthdirect helpline on 1800 022 222 at any time to speak to a registered nurse (known as NURSE-ON-CALL in Victoria) for more information and advice.