Long QT Syndrome

Long QT syndrome is an inherited arrhythmia syndrome that affects 1 out of 2000 in the population.  It is caused by longer electrical recharging of the heart after each heart beat.  This longer recharging time is most commonly due to abnormal channels in heart muscle cells that control the flow of potassium and sodium electrolytes.


Individuals with long QT syndrome may have symptoms from abnormal heart rhythms (arrhythmias), including fainting episodes or seizures. Arrhythmias occur during exercise in some forms of Long QT Syndrome, but may also occur at rest. There is a large amount of variability in the risk of arrhythmias among individuals with long QT syndrome, even within the same family. 

Evaluation and Treatment

Evaluation of the whole family is important since the condition is often passed on to the next generation of a family but may not cause symptoms initially.The specific type of long QT syndrome, identified through genetic testing, has a large impact on recommendations for treatment and risk evaluation. An important part of evaluation is determining the personalized risk level for each individual with long QT syndrome and providing guidance in decisions for implantable defibrillators (ICDs) that prevent sudden death in high risk individuals. Also, certain medications (www.crediblemeds.org) prescribed for a variety of other conditions must be avoided in individuals with long QT syndrome. High intensity exercise or sports may increase arrhythmia risk, and thoughtful, personalized counseling to set guidelines is often needed.

Learn more about our Inherited Arrhythmia Team on our Inherited Cardiomyopathies and Arrhythmias Team page.

Make an Appointment

To make an appointment for expert consultation for a suspected or known inherited cardiomyopathy or arrhythmia condition, contact us toll-free at 888-287-1082 and ask to speak with our program nurse coordinator, Barb Steeves. Please visit our Make a Cardiovascular Appointment page for more information about what to expect when you call us.​