Long QT Syndrome

What is Long QT Syndrome?

Long QT syndrome (LQTS) is a rare, usually congenital disorder that causes an irregular heartbeat. This can cause sudden, dangerous arrhythmias and in some cases ventricular fibrillation, usually in response to exercise or stress.

Baptist Health is known for advanced, superior care for patients with heart disease and the diagnosis, management and treatment of long QT syndrome. You will appreciate timely appointments and a professional, friendly atmosphere where we take time to listen to your concerns. At Baptist Health, you have access to the region’s most comprehensive, multidisciplinary team of specialists and innovative therapies, including many available only through specialized clinical trials. In every way, we work to demonstrate the utmost in excellent care to those who trust us with their health.

Signs and Symptoms

Many people with LQTS normally display no signs or symptoms. Symptoms may be triggered by strenuous exercise, emotional stress, sudden loud noises or surprises, or a slow heart rate during sleep. The main symptoms of LQTS are:

  • Fast, erratic or abnormal heartbeat
  • Fainting or loss of consciousness


Because LQTS is largely congenital, and most people with LQTS are likely to experience their first episode as a child or young teen, LQTS is usually diagnosed early. A diagnosis of LQTS after the age of 40 is extremely rare. To determine if you have long QT syndrome, your doctor will start by reviewing your symptoms, risk factors, and family and medical histories, and performing a physical exam. If your doctor suspects you may have LQTS, he or she will then order an EKG or stress test.

Electrocardiogram (EKG): This test measures the electrical activity of the heart and can help determines if parts of the heart are enlarged, overworked or damaged. The heart’s electrical currents are detected by 12 to 15 electrodes that are attached to the arms, legs and chest via sticky tape.

Stress Testing: This test is conducted during exercise. If a person can't exercise, medicine is given to increase heart rate. Used along with an EKG, the test can show changes to the heart’s rate, rhythm or electrical activity as well as blood pressure. Exercise makes the heart work hard and beat fast while heart tests are administered.


Though LQTS is most often a congenital disease, meaning it is inherited, it can also be caused by:

  • Certain medications, including antiarrhythmics, some antibiotics, antidepressants, cholesterol medications and diuretics
  • Low potassium, magnesium, and sodium levels (this may be caused by anorexia, bulimia, severe diarrhea or vomiting, or certain thyroid disorders)

Risk Factors

Risk factors that can contribute to LQTS include:

Family history: A family history of LQTS increases your risk, particularly if the condition has been diagnosed in siblings or direct ancestors.

Gender: Women are at greater risk for LQTS than men, and are more likely to experience symptoms or complications from the disorder during menstruation or shortly after childbirth. Boys who have LQTS see a decreased risk of symptoms and complications after puberty.

Children who are deaf at birth: The same genetic factors that cause congenital deafness are also known to cause LQTS, putting those born without hearing at greater risk for the disorder.


While there is no way to prevent congenital LQTS, some non-congenital types of LQTS are easily prevented by getting the proper amounts of potassium, sodium and magnesium in your diet.


There are more than a dozen different types of LQTS that carry varying degrees of risk for arrhythmias that can lead to heart failure or sudden death. If you are diagnosed with a form of LQTS, certain lifestyle changes, medications or a surgical implant can greatly improve your prognosis.

Treatment and Recovery

If you are diagnosed with LQTS, your doctor may recommend lifestyle changes, medication, and possibly a surgical implant to prevent or control your symptoms.

Lifestyle Changes
Reducing the amount of prolonged or strenuous physical activity, maintaining the proper levels of potassium and other key minerals in your diet and avoiding stress will help you manage your LQTS.

Beta-blockers are the most common type of medication prescribed for LQTS. 

Avoiding Certain Medications
There are many types of medications that may increase the risk of complications from LQTS, most notably certain antiarrhythmics, antidepressants, certain antibiotics, cholesterol medications and diuretics. If you have been diagnosed with LQTS, consult your doctor before taking any over-the-counter or prescription medications to ensure you are not putting yourself at increased risk.

Surgical Procedures
To prevent or correct arrhythmias associated with LQTS, your doctor may recommend implanting a surgical device. These are minor procedures that typically require a hospital stay of 24 hours or less.

  • Implantable cardioverter-defibrillator (ICD): This device monitors your heart rhythm and produces electrical shocks when needed to control rapid and abnormal heart beats, and restore a normal rhythm to your heart.
  • Pacemaker: This device helps the heart maintain a normal rhythm.


Left undiagnosed and untreated, LQTS can have serious consequences, including:

Torsades de pointes ('twisting of the points): This is a specific type of arrhythmia common to LQTS in which the two lower chambers (ventricles) of your heart beat fast and uncontrollably, making the waves on an EKG monitor look twisted. This causes less blood to be pumped out of your heart, decreasing blood flow to your brain and causing sudden fainting, often without warning. Episodes that occur while swimming, driving or engaging in extreme sports or thrill-seeking activities can cause serious injury or death.

Ventricular fibrillation: This condition causes the ventricles to beat so fast that your heart quivers and stops pumping blood. Unless your heart is shocked back into a normal rhythm by a device called a defibrillator, ventricular fibrillation can lead to brain damage and death.

Seizures: Those with LQTS are at greater risk for seizures, which may be triggered in some cases by a decreased flow of oxygen to the brain.

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