Long QT Syndrome (LQTS)


  • Long QT Syndrome (LQTS) is a condition affecting the electrical system of the heart, which increases the risk for an abnormally fast and chaotic heart rhythm. This abnormal heart rhythm can trigger a fainting spell, a seizure, or sudden cardiac death.
  • Long QT syndrome an inherited condition, and can be triggered in some cases by exercise, a sudden loud noise, and certain medications that prolong the QT interval. There is also an ‘acquired’ Long QT syndrome caused by certain medications, electrolyte imbalances, or other medical conditions.
  • Long QT syndrome is the most common of the genetic arrhythmia conditions and is treatable.
  • Long QT syndrome is estimated to affect approximately 1 in 2,500 people of all ages, around the world. Most have Long QT type 1 or Long QT type 2, but there are several rarer types. A genetic test is used to determine the Long QT type.

Treatment/Standard of Care

Diagnosing Long QT syndrome includes looking at the clinical and family history, as well as cardiac testing. A normal ECG does not ‘rule out’ the diagnosis, and the standard recommendation is to see a cardiac specialist for evaluation.

Treatment includes medication, cardiac devices and avoiding other medications and conditions that can provoke an arrhythmia.

Additional Resources

Please note: The Canadian SADS Foundation provides links to external websites for informational purposes only. While we regard these as reputable sources of information, please be aware that The Canadian SADS Foundation is not responsible for the accuracy, legality, or content of the external site or for that of subsequent links.

Genetics Education Canada (GECKO)

Information from Genetics Education Canada (GECKO) for family doctors about Long QT syndrome as well as when to refer to Cardiology or Genetics

Credible Meds

Website with a database of medications (prescription and over-the-counter medications) that could cause prolonged QT interval or arrhythmia.

There is also a free Credible Meds app available in 5 languages, to look up medications.

Heart and Stroke

Heart and Stroke Foundation patient page on Long QT syndrome.

Nova Scotia Health

Nova Scotia Health pamphlet on Long QT syndrome.

Alberta Health

Alberta Health website has a page on Long QT Syndrome.

Hear From Patients Living With Long QT Syndrome

The Guthrie's Family Story

Read about The Guthrie’s journey with LQTS.