Congenital long QT syndrome (LQTS) is an inherited disorder affecting the heart’s electrical system. It is one of the conditions associated with sudden death in young athletes.

The life-threatening arrhythmias seen with LQTS are more likely to occur during exercise, so in many people with this condition, exertion must be limited.

However, there are several types of LQTS, and the risk of participating in exercise varies among them, as well as among different individuals. Exercise recommendations with LQTS have to be individualized.

What Is Long QT Syndrome?

Congenital LQTS is a genetic abnormality that delays the “recharging” of cardiac cells after they have been “fired off” by the heart’s electrical system. This delay is manifested by a prolonged QT interval as evidenced by an electrocardiogram (ECG).

If you have congenital LQTS, it is important for you and your doctor to determine which kinds of exercise are permissible for you and which kinds need to be avoided. 

The electrical abnormality associated with LQTS can produce cardiac arrhythmias (a form of ventricular tachycardia called torsades de pointes) which can lead to syncope (temporary loss of consciousness) or sudden death.

In many people born with LQTS, the risk of developing these dangerous arrhythmias increases during exercise.

Generally, a person with LQTS has no symptoms whatsoever until they have sudden episodes of ventricular tachycardia (again, usually during exertion). When this arrhythmia occurs, symptoms may vary from a few seconds of intense dizziness all the way to sudden unconsciousness, and even death from cardiac arrest.

While LQTS is an inherited disorder, there are many variants of it (corresponding to several different genes that may be involved). While some variants have a high risk of sudden death, others are far less dangerous.

Often, those who are at the highest risk will have a strong family history of individuals who have experienced syncope or sudden death, most often during exercise. Anyone who has such a family history should be evaluated for possible LQTS.

LQTS is often treated with beta-blockers and by avoiding drugs that cause further prolongation of the QT interval. If the risk of sudden death is judged to be high, an implantable defibrillator may be required.

In addition, anyone with LQTS should be given specific recommendations regarding what is considered low- and high-risk in terms of exercise.

Exercise Recommendations for Young Athletes With LQTS

People with LQTS should avoid high-intensity activities (e.g., basketball, weight lifting) and limit themselves to low-intensity sports (e.g., bowling, golf) if either one of the following applies to them:

  • They have a history of loss of consciousness (syncope) or being resuscitated from cardiac arrest within the last 3 months.
  • They have not had a complete diagnostic workup and evaluation, preferably with a genetic cardiologist or heart rhythm specialist experienced in LQTS.

In general, a person with LQTS who is not in a high-risk category can participate safely in low-intensity exercise and moderate-intensity exercise (e.g, baseball and volleyball).

In some cases, people with LQTS can be classified into specific variants, or subgroups, and different activity recommendations may be optimal for some of these variants.

Regardless of risk group, every person with LQTS should talk with their doctor about specific exercise recommendations.

For instance, people with LQTS type 3 appear to have a somewhat lower risk during exercise than those with other types; people with LQTS type 1 may be at particular risk during swimming or diving.

In November 2015, exercise recommendations for competitive athletes with LQTS were formally updated by the American Heart Association and the American College of Cardiology. These recommendations were intended to liberalize exercise recommendations as much as possible, while maintaining a reasonable level of safety for athletes with LQTS who wish to participate in competitive sports.

Experts now recommend that, if young athletes with LQTS have no symptoms (specifically, they have had no episodes of lightheadedness or syncope associated with exercise), or if they have had no symptoms while on treatment in the last three months, they may participate in competitive sports if:

  • They, their healthcare providers, and their parents or guardians (if they are minors) understand the potential risks involved with competitive athletics and are willing/able to take appropriate precautions.They avoid taking any drugs that prolong the QT interval.They maintain adequate electrolyte and hydration replacement.They avoid overheating and heatstroke.They obtain a personal automatic external defibrillator (AED) as part of their routine personal sports equipment.Team officials are trained and prepared to take appropriate action if an emergency should arise, including the capability and the willingness to use the AED.

Any athlete with LQTS who wants to participate competitively should be evaluated by a long QT specialist prior to competitive athletics, though these recommendations have allowed many athletes with LQTS to enjoy competitive sports as long as they and their coaches are willing to accept a certain amount of personal responsibility for their safe participation.

A Word From Verywell

Congenital LQTS is a genetic disorder of the heart’s electrical system that can increase a person’s risk of developing dangerous cardiac arrhythmias, especially during exercise. It is important for anyone with this condition to work with their doctor to determine what types of exercise they can engage in safely and what precautions they should take while doing so.