Long QT Syndrome

What is long QT syndrome?

Long QT Syndrome (LQTS) is an inherited condition that affects the heart’s electrical rhythm and can cause fast, erratic heartbeats. It is named for the prolonged QT interval it causes on an electrocardiogram (ECK or EKG).

Left untreated, LQTS can be a life-threatening condition that can lead to sudden cardiac death. LQTS causes approximately 3,000 to 4,000 sudden deaths of children and young adults each year in the United States.

LQTS is fairly rare, it is estimated that about 1 in every 2,500 children born have the condition.

What are the types of long QT syndrome?

There are three types of LQTS:

  • LQT1 is more likely to cause symptoms with exercise or emotional stress
  • LQT2 is more likely to cause symptoms with emotional stress
  • LQT3 is more likely to cause symptoms during periods of rest or sleep

What are the symptoms of long QT syndrome?

Some children with LQTS have no symptoms. This makes family screening particularly important.

Symptoms of LQTS can include:

  • fast heart beat (palpitations)
  • fainting (syncope) during periods of strenuous exercise or emotional distress
  • seizures
  • cardiac arrest

What are the causes of long QT syndrome?

In many cases, LQTS is caused by an inherited genetic mutation passed down from a family member. Children with a parent or sibling who has LQTS have a 50 percent chance of having it as well.

In some cases, LQTS may also be caused by certain mediations.

How we care for long QT syndrome

Early diagnosis of LQTS is important. The Inherited Cardiac Arrhythmia Program at Boston Children’s Hospital specializes in family-based services for children with inherited arrhythmias like long QT syndrome. The program meets with and assesses entire families all at once, usually in one day. Our specialists use genetic testing to identify all family members at risk of developing the condition.