Long QT Syndrome: Exercise Recommendations

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Long QT syndrome (LQTS), an inherited disorder affecting the heart’s electrical system, 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, affected individuals usually are not banned from activity altogether. Knowing what's permissible is key to their staying safe.

What Is Long QT Syndrome?

LQTS is a congenital abnormality that delays the “recharging” of cardiac cells after they have been been “fired off” by the heart's electrical system. This delay is manifested by a prolonged QT interval on the ECG. The electrical abnormality associated with LQTS can produce cardiac arrhythmias (a form of ventricular tachycardia called torsades de pointes) which can lead to syncope (loss of consciousness) or sudden death.

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

Generally, with LQTS, there are no symptoms whatsoever until the affected person experiences 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 death from cardiac arrest. The diagnosis is made by examining the ECG, which shows a prolonged QT interval.

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, patients 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.

LQTS is often treated with beta blockers, and 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.

What Are the General Exercise Recommendations For Young Athletes With LQTS?

People with LQTS are recommended to restrict their activities to low-intensity sports if one of the following applies to them:

  1. history of loss of consciousness (syncope) or being resuscitated from cardiac arrest
  2. QT intervals are very prolonged (that is, a measure called the “corrected QT interval - QTc - is prolonged to at least 470 msec in men, or 480 msec in women)

Anyone with LQTS who is not certain to what extent they should be restricting activity should talk to their doctor.

In general, low-intensity exercises such as bowling or golf, and moderate-intensity exercise such as doubles tennis, biking and skating, are permissible in most other young athletes who have LQTS.

Given the fact that several variants of LQTS are seen, different activity recommendations may be optimal for certain subtypes. 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. So, serious athletes may want to consider having genetic subtyping, in order to allow their exercise recommendations to be tailored to their particular genetic variant.

In November 2015, exercise recommendations for competitive athletes with LQTS were formally updated by the American Heart Association and the American College of Cardiology. Experts now recommend that, if young athletes with LQTS have no symptoms (especially no episodes of lightheadedness or syncope associated with exercise), they may participate in competitive sports IF:

  • They, their physicians, and their parents or guardians (if they are minors) understand the potential risks involved with competitive athletics, and are willing and able to take appropriate precautions
      • they avoid any drugs that prolong the QT interval
    • 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
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Article Sources
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