Sudden cardiac death is the swift and not expected ending of all heart activity. Breathing and blood flow stop right away. Within seconds, the person is not conscious and dies.
Sudden cardiac death is different from sudden cardiac arrest (SCA). SCA is the sudden loss of heart activity due to an irregular heart rhythm. Survival is possible with fast, proper medical care.
Sudden cardiac death in seemingly healthy people under age 35 is rare. It is more common in males than in females.
Heart conditions that are not diagnosed, such as a genetic heart disease, can cause sudden death in teenagers and young adults. A heart condition that hasn't been found by tests may cause a young person to die suddenly during physical activity, such as competitive sports. But sudden cardiac death can happen without physical activity.
Most student athletes compete yearly without a heart incident. If you or your child is at risk of sudden cardiac death, talk with your healthcare professional. Ask about steps you can take to lower the risk.
How common is sudden cardiac death in young people?
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 say that about 1 in 50,000 to 1 in 100,000 young athletes dies of sudden cardiac death each year.
What can cause sudden cardiac death in young people?
The heart has an electrical system that controls how it pumps blood. Changes in the electrical signals that the heart creates often cause sudden cardiac death. A very fast heartbeat causes the lower heart chambers to squeeze fast and in a way that is not coordinated. The heart can't pump blood to the body. This life-threatening type of irregular heartbeat is called ventricular fibrillation.
Anything that strains the heart or damages heart tissue can raise the risk of sudden cardiac death. Some conditions that can lead to sudden cardiac death in young people are:
- Thickened heart muscle, also called hypertrophic cardiomyopathy. This genetic condition is one of the more common causes of sudden cardiac death in young people. It causes the heart muscle to become too thick. This can lead to fast heartbeats.
- Long QT syndrome. This heart rhythm condition can cause fast, chaotic heartbeats. It's linked to fainting for no reason and sudden death, especially in young people. If you are born with this condition, it's called congenital long QT syndrome. If it is caused by a medicine or another health condition, it is called acquired long QT syndrome.
- Other heart rhythm conditions. Other types of irregular heartbeats can cause sudden cardiac death. These include Brugada syndrome and Wolff-Parkinson-White syndrome.
- Forceful hit to the chest. A blunt chest injury that causes sudden cardiac death is called commotio cordis. Commotio cordis may happen in athletes who are hit hard in the chest by sports equipment or by another player. This condition does not damage the heart muscle. Instead, it changes the heart's electrical signaling. The blow to the chest can trigger ventricular fibrillation. The hit must occur at a specific time in the heart signaling cycle.
- Heart condition present at birth, also called a congenital heart defect. Some people are born with changes in the heart and blood vessels. These changes can reduce blood flow and lead to sudden cardiac death.
How can parents, coaches and others know if a young person is at risk of sudden cardiac death?
Many times, sudden cardiac death happens without warning. Or warning signs may not be noticed. Ask a healthcare professional if a checkup is needed for anyone who has:
- Fainting, also called syncope. Fainting that cannot be explained and occurs during activity or exercise could mean there is a heart condition.
- Shortness of breath or chest pain. These symptoms could be a sign of a heart condition. But conditions such as asthma also can be the cause. That is why it is important to get a complete health checkup.
- Family history of sudden cardiac death. This family history makes a person more likely to have the same type of heart event. (6p6; 8p5) If there is a family history of deaths that cannot be explained, talk with a healthcare professional about screening options.
Can sudden death in young people be prevented?
Sometimes. Depending on the underlying condition, medicine or surgery may be recommended to lower the risk of sudden death. For example, a device called an implantable cardioverter-defibrillator (ICD) may be placed in the chest. The device continuously checks the heart's rhythm. If a life-threatening heartbeat change happens, the ICD gives electrical shocks to reset the heart rhythm.
Many athletic training centers have a portable machine called an automated external defibrillator (AED). An AED is used to treat someone during cardiac arrest. It gives shocks to reset the heartbeat. No training is needed to use it. The machine tells you what to do. It's programmed to give a shock only when needed.
If you're at high risk of sudden cardiac death, a healthcare professional may tell you not to play competitive sports.
Who should be screened for sudden death risk factors?
Expert groups such as the American Heart Association, the American College of Cardiology and the American Academy of Pediatrics suggest that children get screened before they take part in a competitive sport. Screening is very important if you have a family history or risk factors for conditions that cause sudden cardiac death.
In the United States, a typical screening involves a physical exam and questions about family health history. But worldwide, there's some debate over what screening tests to do. Most American expert groups don't suggest that all children get a quick test to check the heartbeat, called an electrocardiogram (ECG or EKG). Most European groups do suggest routine ECG screening.
One Italian study found that mandatory heart checks of young people with an ECG results in lower rates of sudden cardiac death. But some worry that this type of screening can suggest something is wrong when there is not a problem. This is called a false-positive result. Another worry is that doing routine ECG tests would lead to too many instances of finding conditions that may never cause harm.
Also, it's not clear that routine ECGs for athletes can prevent sudden cardiac death. Still, such testing might help spot some athletes who are at a higher risk.
The American Heart Association does not recommend sudden cardiac death screening for young people who are not athletes and who don't have heart disease symptoms.
Should young adults with a heart condition avoid or limit physical activity?
It depends. If you are at risk of sudden cardiac death, talk with your healthcare professional about physical activity. Whether you can safely exercise or play sports depends on your specific heart condition. Do not play full-contact sports if you have a medical device in your chest to find and stop irregular heartbeats. A direct blow to the chest may move the device.
Your health professional can tell you which sports and types of exercise are safe for you or your child.
