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 is not identified may cause a young person to suddenly die during physical activity, such as competitive sports. But sudden cardiac death can occur without activity.

Most student athletes compete yearly without a heart incident. If you or your child is at risk of sudden cardiac death, talk to your healthcare professional. Ask about steps you can take to lower the risk.

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 one in 50,000 young athletes to one in 100,000 dies of sudden cardiac death each year.

Changes in the heart's electrical signaling often causes 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 increase 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 the most common cause of sudden cardiac death in young people. It causes the heart muscle to grow too thick. The thickening makes it hard for the heart to pump blood. This can cause 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 it, it's called congenital long QT syndrome. If it is caused by a medicine or health condition, it is called acquired long QT syndrome.
• Other heart rhythm conditions. Other irregular heart rhythms 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 occur 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.

Many times, sudden cardiac death occurs without warning. Or warning signs may not be noticed. Ask if a health 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 problem.
• Shortness of breath or chest pain. These symptoms could be a sign of a heart problem. 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. If there is a family history of deaths that cannot be explained, talk with a healthcare professional about screening options.

Sometimes. If you are at high risk of sudden cardiac death, a healthcare professional may tell you not to play competitive sports.

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 heart rhythm change occurs, the ICD delivers electrical shocks to reset the heart.

Many athletic training centers have a portable device called an automated external defibrillator (AED). An AED is used to treat someone during cardiac arrest. It delivers shocks to reset the heart rhythm. No training is needed to use it. The device tells you what to do. It's programmed to give a shock only when necessary.

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 checks of young people with an electrocardiogram (ECG) leads to lower rates of sudden cardiac death. But some worry 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 screening would lead to overdiagnosis of conditions that may never cause harm.

One idea is to give routine ECGs to athletes before they play competitive sports to identify risk and prevent sudden cardiac death. But it's not clear that routine ECGs for athletes can prevent sudden cardiac death. However, such testing might help identify some who are at a higher 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 does not recommend sudden cardiac death screening for young people who are not athletes and who don't have heart disease symptoms.

It depends. If you are at risk of sudden cardiac death, talk to your healthcare professional about physical activity. Whether you can safely participate in exercise or sports depends on your specific 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.

March 20, 2024

Original article: https://www.mayoclinic.org/diseases-conditions/sudden-cardiac-arrest/in-depth/sudden-death/art-20047571