Sudden death in young people is rare, but those at risk can take precautions. Find out more about the risk factors, causes and treatments.

By Mayo Clinic Staff

Sudden cardiac death is the swift and unexpected ending of all heart activity. Breathing and blood flow stop right away. Within seconds, the person becomes unconscious and dies.

Sudden cardiac death isn't the same as sudden cardiac arrest (SCA). SCA is the sudden loss of heart activity due to an irregular heart rhythm. Survival is possible with fast, appropriate medical care.

Sudden cardiac death in seemingly healthy people under age 35 is rare. It's more common in males than in females.

When sudden death occurs in adolescents and young adults, it's sometimes due to undiagnosed heart conditions such as a genetic heart disease. The undetected heart problem may cause a young person to suddenly die during physical activity, such as playing competitive sports. However, sometimes sudden cardiac death can occur without exertion.

Most student athletes compete yearly without a heart incident. If you or your child is at risk of sudden cardiac death, ask your health care provider about precautions you can take.

Most sudden cardiac deaths are in older adults, particularly those with heart disease. Yet sudden cardiac arrest is the leading cause of death in young athletes. Estimates vary, but some reports suggest that about 1 in 50,000 to 1 in 80,000 young athletes die of sudden cardiac death each year.

Sudden cardiac death is often caused by faulty electrical signaling in the heart. A very fast heartbeat causes the lower heart chambers (ventricles) to quiver uselessly instead of pumping blood. This irregular heart rhythm is called ventricular fibrillation.

Any condition that puts a strain on the heart or damages heart tissue can increase the risk of sudden death. Some conditions that can lead to sudden cardiac death in young people are:

  • Thickened heart muscle (hypertrophic cardiomyopathy). The most common cause of sudden cardiac death in young people is this genetic condition that causes the heart muscle to grow too thick. The thickening makes it hard for the heart to pump blood and can cause fast heartbeats.
  • Heart rhythm disorders. Long QT syndrome is a heart rhythm condition that can cause fast, chaotic heartbeats. It's linked to unexplained fainting and sudden death, especially in young people. Long QT syndrome may be present at birth (congenital long QT syndrome) or caused by an underlying medical condition or medication (acquired long QT syndrome).

    Other heart rhythm disorders that can cause sudden cardiac death include Brugada syndrome and Wolfe-Parkinson-White syndrome.

  • Blunt chest injury. A hard hit to the chest that causes sudden cardiac death is called commotio cordis. Commotio cordis may occur in athletes who are hit hard in the chest by sports equipment or by another player. This condition doesn't damage the heart muscle. Instead, it changes the heart's electrical signaling. The blow to the chest can trigger ventricular fibrillation if it strikes at a specific time in the signaling cycle.
  • Heart structure problem present at birth (congenital heart defect). Some people are born with changes in the heart and blood vessels that can reduce blood flow and lead to sudden cardiac death.

Many times, sudden cardiac death occurs without warning. When warning signs occur, they may go unrecognized. Take note and ask if a health checkup is needed for anyone who has:

  • Unexplained fainting (syncope). Fainting that occurs during activity or exercise could mean that there's a heart problem.
  • Shortness of breath or chest pain. These symptoms could be a sign of a heart problem. But they can be caused by asthma, so it's important to get a thorough health evaluation.
  • Family history of sudden cardiac death. Having a family history of sudden cardiac death makes a person more likely to have the same type of heart event. If there's a family history of unexplained deaths, talk with a health care provider about screening options.

Sometimes. If you're at high risk of sudden cardiac death, a health care provider will likely suggest that you avoid competitive sports.

Depending on the underlying condition, medication or surgery may be recommended to reduce the risk of sudden death. For example, a medical device called an implantable cardioverter-defibrillator (ICD) may be implanted in the chest to continuously monitor the heart's rhythm. If a life-threatening heart rhythm problem occurs, the ICD delivers electrical shocks to reset the heart.

Many athletic training centers have a device called an automated external defibrillator (AED) that is readily available to use. An AED is a portable device used to treat someone during cardiac arrest. An AED delivers shocks to reset the heart.

There's debate in the medical community about screening young athletes in attempt to identify those at high risk of sudden death.

One Italian study found that mandatory heart evaluation of young people with an electrocardiogram (ECG or EKG) leads to lower rates of sudden cardiac death. But some worry this type of screening can lead to false-positive results — signs that there's a problem when there really isn't. Another worry is that screening would lead to overdiagnosis of conditions that may never cause any harm.

It's not clear that routine ECGs given before athletes are cleared to play competitive sports can prevent sudden cardiac death. However, such testing might help identify some who are at increased risk.

If you have a family history or risk factors for conditions that cause sudden cardiac death, screening is typically recommended.

The American Heart Association doesn't recommend sudden cardiac death screening for young people who are not athletes and who don't have heart disease symptoms.

It depends. If you're at risk of sudden cardiac death, talk to your health care provider about physical activity. Whether you can safely participate in exercise or sports depends on your specific condition. For example, if you have a medical device implanted in your chest to detect and stop irregular heartbeats, you should avoid full-contact sports. A direct blow to the chest may move the device.

Your care provider can tell you which sports and types of exercise are safe for you or your child.

June 10, 2022