Summary

  • Fainting can be a symptom of long QT syndrome and is sometimes mistaken for a seizure.
  • You should be investigated for long QT syndrome if you faint for no apparent reason, or during or after exercise or emotional excitement.
  • Long QT syndrome is usually inherited, although it can be acquired after taking certain medication.
  • If you have long QT syndrome, always tell your doctor before they give you a prescription.

Long QT syndrome is a relatively common cause of sudden death in children and young adults. Long QT syndrome is diagnosed by electrocardiograph (ECG). Fainting can be a symptom of long QT syndrome and is sometimes mistaken for a seizure. About one third of people who have long QT syndrome do not have any symptoms.

Long QT syndrome warning signs

You should be investigated for long QT syndrome if:
  • you faint for no apparent reason
  • you faint during or shortly after exercise or emotional excitement
  • there is a family history of unexplained fainting or sudden death in your family.

Types of long QT syndrome

There are two main types of long QT syndrome: inherited long QT syndrome and acquired long QT syndrome.

Inherited long QT syndrome

There are two types of inherited long QT syndrome:
  • Romano-Ward syndrome – is being recognised with increasing frequency. Researchers have found more than 15 genes that cause long QT syndrome, and more are expected to be discovered in the future. Genetic testing for long QT syndrome is now available.
  • Jervell and Lange-Nielson syndrome – this form is rare and also causes deafness.

Acquired long QT syndrome

Long QT syndrome can also be acquired by taking certain over-the-counter medications and some prescribed medications. If you have long QT syndrome, always tell your doctor before they give you a prescription. There is an updated list of medications to avoid at Center for Education and Research on Therapeutics.

Event triggers of long QT syndrome

An event can be triggered by:
  • exercise
  • being startled by a loud noise, such as a horn, ringing telephone or alarm clock
  • exams, tests or other stressful situations
  • anger or crying.

Treatment for long QT syndrome


Treatments include:
  • medications – beta blockers are effective for 90 per cent of people with long QT syndrome.
  • implantable cardioverter-defibrillators (ICDs) – ICDs are devices placed inside the body to detect and correct abnormal heart rhythms. ICDs may be necessary for patients that do not respond to beta blocker therapy.

Where to get help

  • Your doctor
  • SADS (Sudden Arrhythmic Death Syndrome) Australia. Tel. 0430 911 717

Things to remember

  • Fainting can be a symptom of long QT syndrome and is sometimes mistaken for a seizure.
  • You should be investigated for long QT syndrome if you faint for no apparent reason, or during or after exercise or emotional excitement.
  • Long QT syndrome is usually inherited, although it can be acquired after taking certain medication.
  • If you have long QT syndrome, always tell your doctor before they give you a prescription.

More information

Genes and genetics

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A-Z of genetic conditions

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This page has been produced in consultation with and approved by: Victorian Clinical Genetics Services (VCGS)

Last updated: June 2014

Page content currently being reviewed.

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