Long QT syndrome (LQTS) is a medical condition that affects the normal electrical activity of the heart.

The term QT refers to the portion of the tracing on an electrocardiogram (EKG) that reflects the change in heart rhythm. Doctors may also call this condition Jervell and Lange-Nielsen syndrome or Romano-Ward syndrome.

While LQTS doesn’t always cause symptoms, it does have the potential to cause life-threatening heart arrhythmias. People with LQTS can also experience fainting spells. If you have LQTS, it’s important you manage it to prevent these from happening.

A doctor may identify LQTS on an EKG before a person ever has symptoms. An EKG is a visual tracing of electrical activity in the heart.

A typical tracing has a small bump called a “P” wave, followed by a large peak called a QRS complex. After this peak is another bump that’s usually larger than the “P” wave called a “T” wave.

Each of these changes signals something that’s happening in the heart. In addition to looking at each portion of the EKG, doctors also measure the distance between them. This includes the distance between the start of the Q portion of the QRS complex and the T wave.

If the distance between these is consistently longer than expected, they may diagnose you with LQTS.

LQTS is concerning because the heart relies on an even, steady rhythm and electrical activity to beat correctly. LQTS makes it easier for the heart to beat out of time. When that occurs, oxygen-rich blood doesn’t pump to the brain and body.

Not everyone with LQTS has symptoms, but those who do might notice:

  • fluttering feelings in the chest
  • noisy gasping when sleeping
  • passing out for no known reason

According to the National Heart, Lung, and Blood Institute, one out of every 10 people with LQTS experience sudden death or sudden cardiac death as the first sign of the disorder.

This is why it’s so important to regularly follow up with a doctor if you have a family history of LQTS or an irregular heartbeat.

LQTS can be either inherited or acquired, meaning that something beyond genetics causes it.

Seven types of inherited LQTS exist. They are numbered LQTS 1, LQTS 2, and so on. Researchers have identified more than 15 different types of genetic mutations that can lead to LQTS.

Acquired LQTS can be due to taking certain medications, including:

  • antiarrhythmics
  • antibiotics
  • antihistamines
  • antipsychotics
  • cholesterol-lowering medicines
  • diabetes medications
  • diuretics

Some people may have unknowingly inherited the condition, but don’t realize they have it until they start taking a medication that aggravates it.

If you take any of these medications for a long period of time, your doctor might regularly monitor your heart rhythm on an EKG to check for anything unusual.

Several other things can cause LQTS, especially those that cause a loss of potassium or sodium from your bloodstream, such as:

  • severe diarrhea or vomiting
  • anorexia nervosa
  • bulimia
  • malnutrition
  • hyperthyroidism

Having a family history of LQTS is a major risk factor for the condition. But this can be hard to know, since it doesn’t always cause symptoms.

Instead, some may just know that a family member died unexpectedly or drowned, which can happen if someone passes out while swimming.

Other risk factors include:

  • taking medications known to prolong QT interval
  • being born with full or partial deafness
  • having severe diarrhea or vomiting
  • having a history of medical conditions such as anorexia nervosa, bulimia, or some thyroid disorders

Women are more likely than men to have LQTS.

There’s no cure for LQTS. Instead, treatment usually involves reducing your risk of developing a heart arrhythmia by:

  • taking medications called beta blockers to reduce too fast heart rhythms
  • avoiding medications known to prolong QT interval
  • taking sodium channel blockers if you have LQTS 3

If you experiencing fainting or other signs of an abnormal heart rhythm, your doctor may recommend more invasive treatment, such as implanting a pacemaker or implantable cardioverter defibrillator. These devices recognize and correct abnormal heart rhythms.

Sometimes a doctor will recommend an ablation or surgery to repair the electrical nerves that incorrectly transmit rhythms.

If you have LQTS, there are a few things you can do to avoid sudden cardiac arrest.

These include:

  • Reducing stress and anxiety whenever possible. Consider giving yoga or meditation a chance.
  • Avoiding strenuous exercise and some types of sports, such as swimming. Swimming, especially in cold water, is a known trigger for LQTS complications.
  • Eating more potassium-rich foods.
  • Avoiding loud noises that are known to trigger LQTS 2 (if you have this type), such as a loud alarm clock buzzer or telephone ringer.
  • Telling close friends and family about your condition and what to watch for, such as fainting or breathing issues.

According to the National Heart, Lung, and Blood Institute, roughly 1 in 7,000 people have LQTS. It’s possible more people could have it and just aren’t diagnosed. This makes it hard to know exactly how LQTS impacts someone’s life expectancy.

But people who haven’t had any fainting or heart arrhythmia events by age 40 usually have a low risk of severe complications, according to the Sudden Arrhythmia Death Syndromes Foundation.

The more episodes a person has, the more at risk they are for a life-threatening arrhythmia.

If you have any family history of this condition or unexplained sudden deaths, make an appointment with a doctor to have an EKG done. This will help to identify anything unusual about your heart’s rhythm.