Long QT Syndrome (LQTS)

Long QT syndrome (LQTS) is a condition that affects the flow of ions into and out of the cells in the heart. This abnormal flow of ions can prolong the patient’s QT interval, which is measured on an ECG.  The prolonged QT interval affects how electrical impulses travel through the heart.  Electrical activity may be transmitted abnormally through the lower heart chambers (ventricles) leading to potentially life-threatening ventricular arrhythmias. LQT syndrome is usually, but not always, inherited.

Symptoms of LQTS: 

Symptoms of LQTS include dizziness, palpitations, fainting, or, sudden death. Again, patients may be diagnosed with seizures or drop spells, especially following sudden startles, such as fire alarms. These symptoms can also be triggered by stress or physical activity, particularly swimming.  Patients with LQTS frequently have an abnormality on a resting ECG.


Screening for LQTS includes measuring the QT interval on a resting ECG, but may also be measured during or after exercise to check for QT prolongation with physical activity. 

Genetic testing and genetic counseling can be valuable tools when evaluating patients, and their family members, for channelopathies.  The genetic changes that cause some channelopathies may even guide your cardiologist or electrophysiologist (cardiologist who specializes in heart rhythm conditions) to choose one specific medication.  If a known disease-causing genetic mutation (change in the gene’s sequence or pattern) is found in a patient, it can help direct future testing in other family members to determine their risk of developing the disease.


Treatment of Long QT Syndrome focuses on preventing and treating ventricular arrhythmias.  Your cardiologist may prescribe medications which lessen the effect of catecholamines in our bodies, or which affect the ion channels of the heart cells, or other types of medications used to treat abnormal heart rhythms. Most often, a beta blocker is prescribed.

Implantation of an implantable cardioverter defibrillator (ICD or defibrillator) may be indicated for certain patients, especially those who have had a life-threatening arrhythmia (such as ventricular tachycardia or ventricular fibrillation). 

Depending on the diagnosis, and the severity and frequency of a patient’s episodes, a surgery (sympathetic denervation) to cut the nerve that makes the heart respond to catecholamines may be offered.  This surgery may take place before or after ICD implantation. Even after ICD implantation, patients may be required to continue with their medications and activity restrictions. 

Lifestyle Changes:

Some patients with Long QT Syndrome may be restricted from competitive sports, and some may require even stricter limitations. Even if there are some restrictions, it will be important to discuss the activities that are safe and appropriate for the patient, and to focus on what CAN be done and how to stay safe when participating in activities.

Patients with Long QT Syndrome should avoid medications that prolong the QT interval. A comprehensive and up-to-date list can be found at www.crediblemeds.org.