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What is Short QT Syndrome?

Short QT syndrome is a rare heart disorder that can sometimes cause irregular heartbeats. This heartbeat pattern can cause your child to become very dizzy or faint without warning. The term “short QT” is in reference to the activity in the heart’s lower chambers as measured with an electrocardiogram [ee-lek-troh-CAR-dee-oh-gram] (EKG or ECG). This measurement is called the QT interval.

Although rare, short QT can cause the heart to beat so fast or unpredictably, that a child may develop heart failure or die suddenly .Some doctors think that this syndrome might even be a cause of some sudden infant death syndrome (SIDS) fatalities.

Some of the heart problems caused by short QT syndrome include:

  • Atrial fibrillation [AY-tree-uhl fib-reh-LAY-shun], also called “afib,” and is a type of abnormal heart rhythm that happens in the heart’s upper chambers
  • Ventricular [ven-TRICK-you-lar] fibrillation, which is a very fast and abnormal heart rate that causes sudden death
  • Ventricular tachycardia [tak-eh-car-dee-uh], a very fast hearth rhythm in the heart’s lower chambers


Most children do not have any symptoms of signs of short QT syndrome. You may only find out about your child’s condition because of a doctor’s visit or medical test, genetic testing results, or if you have a family history of the syndrome.

Symptoms of short QT syndrome usually happen when a child is startled, and include:

  • Fainting
  • Heart pounding
  • Afib, or irregular heartbeat
  • Dizziness
  • Trouble breathing
  • Fatigue (getting very tired for no reason)
  • Chest pain

This condition can also cause heart failure and sudden death, which may be the first symptom your child has.

When to See a Doctor

It is important to catch and treat your child’s short QT syndrome as early as you can. It can be fatal if not treated, so it should be treated as soon as possible. Make an appointment to see your child’s doctor if you notice any of the symptoms for short QT syndrome.


Children that have short QT syndrome are born with it. Doctors aren’t sure if it is passed on in the parent’s genes, or if it is a problem that happens in the child’s body as they grow in the womb.

Diagnosis and Tests

Your child’s doctor will do a physical exam and ask you about any symptoms your child may have, including how long they have had them, and how severe they are. If your doctor thinks your child may have short QT syndrome, they will likely order more tests to help confirm the diagnosis.

These other tests may include:

  • An EKG, which is a test that monitors the timing of the heartbeat
  • A Holter monitor, which is a mobile EKG device that is worn for at least a day
  • An event monitor, which is a portable EKG device that is worn for a few weeks
Although not common, sometimes an EKG does not show the short QT interval, and makes it hard to confirm the diagnosis. If this is the case, your doctor may order other tests, such as:
  • Genetic testing, which helps your doctor see if your child has genetic causes for the syndrome
  • Exercise stress test, which is where an EKG is done while your child is walking or running on a treadmill to help the heart beat more
  • A non-exercise stress test, which is where an EKG is performed right after a child is given medicine to help the heart beat faster, like they are playing hard

You may want to seek a second opinion if your child is diagnosed with short QT syndrome.


Treatments for short QT syndrome will depend on your child’s symptoms.

The goal of long QT syndrome treatment is to prevent sudden death by keeping the heart from beating too fast or out of control. Your child’s doctor may also treat heart rhythm disorders as needed.

Treatment may include one or more of the following:

  • Lifestyle changes
  • Medicine
  • Surgery
  • Implanted medical devices.

There are also some lifestyle changes that may help with short QT syndrome. If your child short QT syndrome:

  • Talk to your child’s doctor before starting any medicines to make sure you avoid ones that may cause the QT cycle to be longer.
  • If your child has a fever, contact your child’s doctor. Your child should not run a fever for a long period of time.
  • Make sure your child stays hydrated, especially during times where they are sick and may have a higher chance of getting dehydrated (such as when they are throwing up or have diarrhea).
  • Try to prevent your child from getting startled or scared, or avoid situations that may cause them to get too excited or angry.
  • Don’t allow your child to participate in strenuous sports or exercise
  • Work with your doctor to create a plan just in case your child does have a cardiac event.


Because your child may develop long QT syndrome before birth, there may be nothing you can do to prevent it.
Short QT syndrome is a rare heart disorder that can cause an irregular heartbeat (arrhythmia). Some people may not have any symptoms of short QT syndrome, In others, the irregular heartbeat can cause dizziness, fainting (syncope), and even sudden death.