Long QT

Signs and Symptoms

The most common symptom of long QT syndrome (LQTS) is a sudden loss of consciousness, also known as syncope. The condition may also cause seizures and in some instances, cardiac arrest and sudden death.

The severity of the condition varies greatly. Some people never experience syncope and others may have frequent episodes that could possibly lead to cardiac arrest and sudden death.

It is important to note that symptoms usually occur without warning and are caused by a very fast heart rhythm called torsade de pointes. Syncope may occur during or just after physical exertion, emotional excitement or sudden auditory arousal, such as from an alarm clock.

Diagnosis

Long QT syndrome (LQTS) is usually diagnosed with an electrocardiogram (ECG), which is a picture of the electrical activity of heartbeats. QT refers to a time interval measured on the ECG. People with this disorder have a longer QT interval than other people.

The ECG isn't a perfect test for the condition. Some people with the disorder will have normal tests or it might be normal on some days and abnormal on other days.

LQTS is usually inherited, which means it may affect multiple family members. Each child, sister, or brother of a person with the disorder has a 50 percent chance of inheriting the genetic mutation that causes the condition.

Once a family member is identified with the condition, it is very important to test all other family members. All close relatives should see a cardiologist and have an ECG.

Genetic testing can also help diagnose LQTS. Once genetic testing has identified the genetic mutation causing the condition in a family, other family members can be tested for that same genetic mutation to see if they also inherited it.

If a relative of a person with the disorder has genetic testing and is found not to carry the genetic mutation for the condition, then that relative need not be followed by a cardiologist. This can relieve a lot of stress and worry.

Treatment

It is important to note that with the correct diagnosis and therapy, long QT syndrome (LQTS) is a treatable disorder and most deaths are preventable. Many people with the condition can be treated with medication. A minority of patients will need an implantable cardiac defibrillator.