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 death in people younger than 35, often due to undiscovered heart defects or overlooked heart abnormalities, is rare. When these sudden deaths occur, it's often during physical activity, such as playing a sport, and more often occurs in males than in females.

Millions of elementary, high school and college athletes compete yearly without incident. If you or your child is at risk of sudden death, talk to your doctor about precautions you can take.

Most deaths due to cardiac arrest are in older adults, particularly those with coronary artery disease. Cardiac arrest is the leading cause of death in young athletes, but the incidence of it is unclear. Perhaps 1 in every 50,000 sudden cardiac deaths a year occurs in young athletes.

The causes of sudden cardiac death in young people vary. Most often, death is due to a heart abnormality.

For a variety of reasons, something causes the heart to beat out of control. This abnormal heart rhythm is known as ventricular fibrillation.

Some specific causes of sudden cardiac death in young people include:

  • Hypertrophic cardiomyopathy (HCM). In this usually inherited condition, the walls of the heart muscle thicken. The thickened muscle can disrupt the heart's electrical system, leading to fast or irregular heartbeats (arrhythmias), which can lead to sudden cardiac death.

    Hypertrophic cardiomyopathy, although not usually fatal, is the most common cause of heart-related sudden death in people under 30. It's the most common identifiable cause of sudden death in athletes. HCM often goes undetected.

  • Coronary artery abnormalities. Sometimes people are born with heart arteries (coronary arteries) that are connected abnormally. The arteries can become compressed during exercise and not provide proper blood flow to the heart.
  • Long QT syndrome. This inherited heart rhythm disorder can cause fast, chaotic heartbeats, often leading to fainting. Young people with long QT syndrome have an increased risk of sudden death.

Other causes of sudden cardiac death in young people include structural abnormalities of the heart, such as undetected heart disease that was present at birth (congenital) and heart muscle abnormalities.

Other causes include inflammation of the heart muscle, which can be caused by viruses and other illnesses. Besides long QT syndrome, other abnormalities of the heart's electrical system, such as Brugada syndrome, can cause sudden death.

Commotio cordis, another rare cause of sudden cardiac death that can occur in anyone, occurs as the result of a blunt blow to the chest, such as being hit by a hockey puck or another player. The blow to the chest can trigger ventricular fibrillation if the blow strikes at exactly the wrong time in the heart's electrical cycle.

Many times these deaths occur with no warning, indications to watch for include:

  • Unexplained fainting (syncope). If this occurs during physical activity, it could be a sign that there's a problem with your heart.
  • Family history of sudden cardiac death. The other major warning sign is a family history of unexplained deaths before the age of 50. If this has occurred in your family, talk with your doctor about screening options.

Shortness of breath or chest pain could indicate that you're at risk of sudden cardiac death. They could also indicate other health problems in young people, such as asthma.

Sometimes. If you're at high risk of sudden cardiac death, your doctor will usually suggest that you avoid competitive sports. Depending on your underlying condition, medical or surgical treatments might be appropriate to reduce your risk of sudden death.

Another option for some, such as those with hypertrophic cardiomyopathy, is an implantable cardioverter-defibrillator (ICD). This pager-sized device implanted in your chest like a pacemaker continuously monitors your heartbeat. If a life-threatening arrhythmia occurs, the ICD delivers electrical shocks to restore a normal heart rhythm.

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

Some countries such as Italy screen young people with an electrocardiogram (ECG or EKG), which records the electrical signals in the heart. However, this type of screening is expensive and can produce false-positive results — indications that an abnormality or disease is present when it isn't — which can cause unnecessary worry and additional tests.

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

For anyone with a family history or risk factors for conditions that cause sudden cardiac death, further screening is recommended. Repeat screening of family members is recommended over time, even if the first heart evaluation was normal.

If you're at risk of sudden cardiac death, talk to your doctor about physical activity. Whether you can participate in exercise or sports depends on your condition.

For some disorders, such as hypertrophic cardiomyopathy, it's often recommended that you avoid most competitive sports and that if you have an ICD, you should avoid impact sports. But this doesn't mean you need to avoid exercise. Talk to your doctor about restrictions on your activity.

March 04, 2017