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Could Long QT Syndrome Be What’s Causing You to Faint?

If you’re prone to fainting, you’ll want to figure out what’s going on so you can take steps to treat the cause. After all, you’re at risk of falling and injuring yourself when you pass out. Fainting occurs when your brain doesn’t get enough blood, and a lot of different health conditions can cause it. 

One of those conditions is called long QT syndrome. While it’s not a common trigger for passing out, if you haven’t identified another cause for your fainting spells, you may want to ask your doctor about it.

Shane Rowan, MD, a cardiologist with Banner Health in Colorado, explained more about the condition.

What is long QT syndrome?

Long QT syndrome is a disorder with your heart’s electrical system that can make your heartbeat too fast. When your doctor examines your heart rhythm with an electrocardiogram (EKG), they can observe an interval called the QT interval. “If that interval becomes too long, then your risk of dangerous heart rhythms increases,” Dr. Rowan said. “Long QT syndrome refers to having a long QT interval.”

What are the symptoms?

Fainting or passing out is a common symptom. You might pass out when you’re exercising or experiencing strong emotions. You may also notice heart palpitations, or fluttering in your chest, and if a normal flow of oxygen doesn’t return to your brain, you could have a seizure. Sudden cardiac arrest, which is fatal, can occur if the heart rhythm doesn’t return to normal.

What causes long QT syndrome?

There are two different causes for long QT syndrome:

  • Inherited (or congenital) long QT syndrome: People are born with an abnormality of the electrical system that causes a long QT interval because they inherit a genetic change from one or both of their parents.
  • Acquired long QT syndrome: Medications or electrolyte abnormalities can cause the QT interval to get too long. You could be at risk for long QT syndrome if you take antiarrhythmics, some antibiotics, some antihistamines, some antidepressants, or medications to help prevent nausea. You could have an electrolyte imbalance due to dehydration, diarrhea or an eating disorder. A history of stroke, heart disease or hypothyroidism could also increase your risk . 

Can it be prevented?

You can’t prevent inherited long QT syndrome. You may be able to prevent acquired long QT syndrome by avoiding combinations of medicines that prolong the QT interval or by treating the condition causing an electrolyte imbalance. 

How is it diagnosed?

“The initial diagnosis is usually made by electrocardiogram (ECG or EKG),” Dr. Rowan said. Your doctor may want to conduct follow-up testing such as treadmill tests, echocardiography or genetic testing.

How is it treated?

Treatment depends on which type of long QT syndrome you have. For the acquired type, you can stop taking the medications causing the QT interval to be long. Your doctor can work with you to find other medicines that can help treat your conditions.

Congenital long QT syndrome is usually treated with medicines called beta blockers. Some people who have congenital long QT syndrome may also require treatment with an implantable cardioverter-defibrillator (ICD).

If you have long QT syndrome, your doctor may recommend that you avoid strenuous sports that can trigger abnormal heart rhythms, and steer clear of swimming, since if you faint when you’re swimming, you could drown.

The bottom line

Many health conditions could cause fainting, including a disturbance in the heart’s electrical system known as long QT syndrome. If you’re prone to fainting, you’ll want to talk to your doctor to figure out what’s making you pass out and how you can treat it. 

Experiencing fainting or have concerns about long QT syndrome?

Schedule an appointment with a primary care provider.
Schedule an appointment with a cardiologist.

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