From Cleveland Clinic:

What is sudden arrhythmic death syndrome?

Sudden arrhythmic death syndrome is a heart condition you inherit (in most cases) that affects your heart’s electrical system, giving you an abnormal heart rhythm. Without treatment, this puts you at risk for sudden death.

One of the more common types of sudden arrhythmic death syndrome, Long QT syndrome, happens in an estimated one out of 2,000 newborns. Another type, Brugada syndrome, happens in less than 1% of the population. An estimated one in 10,000 people has CPVT.

Each year, about 200,000 Americans die from sudden cardiac arrest. About 4,000 children and young adults die each year from a SADS condition.

What are the symptoms of sudden arrhythmic death syndrome?

Although symptoms vary somewhat among the different types of sudden arrhythmic death syndrome, common symptoms include:

• Fainting or having a seizure while exercising, excited or afraid.
• Chest pain during exercise.
• Shortness of breath while exercising.

What causes sudden arrhythmic death syndrome?

When a young person dies suddenly and their heart has a normal structure, healthcare providers may suspect the child had an undiagnosed arrhythmia. These conditions that cause arrhythmias, listed above, are usually passed down from parent to child. The chance of passing on these conditions is variable, depending on the exact gene and exact part of the heart involved.