What Causes SCA?

As explained by Simon’s Heart, “there are two main types of heart conditions that lead to sudden cardiac arrest in children: structural and electrical. A structural defect, like cardiomyopathy (enlarged heart), prevents the heart from working properly – it’s too big or the parts are in the wrong place. An electrical defect, like Long QT Syndrome, interrupts the heart’s rhythm, resulting in a dangerous arrhythmia, or abnormal hearth rhythm. These conditions are usually hereditary, but can be acquired in some instances. There are also certain infections that attack the heart and lead to either structural or electrical problems. Some medications can affect the heartbeat and cause harm. Finally, substances like caffeine and drugs can make the heart race, resulting in an arrhythmia.

There are various causes of a sudden cardiac arrest in adults. “Some of the most common causes of sudden cardiac arrest are: low oxygen levels, severe electrolyte abnormalities, a blood clot in the lung (pulmonary embolism), a blood clot in the heart (heart attack), certain drugs, or certain irregular heart rhythms.”

symptoms of sca

The first symptom of SCA is often death, either because the warning signs of an underlying heart condition were not recognized in time or life-saving help was not administered within minutes of the SCA event. When warning signs do occur, the warning signs can include:

Fainting or seizures during or immediately after exercise

Unexplained shortness of breath


Extreme fatigue

Racing heart (feels like it is beating out of your chest)

Sudden and unexplained death of a family member under the age of 50 (e.g. drowning, auto accident, SIDS)

If a student or young adult is having these symptoms, the person and their family should consult a doctor.

How Does COVID impact SCA?

Early data suggests that COVID-19 exposure can impact the hearts of students and young adults, which means now is a good time evaluate your child’s heart health.

The American Medical Society of Sports Medicine (AMSSM) and the National Federation of State High School Associations (NFHS) published Cardiopulmonary Considerations for High School Student-Athletes During the COVID-19 Pandemic: NFHS-AMSSM Guidance Statement. This guidance statement addresses the recommended evaluation of high school student-athletes who have had COVID-19 exposure, symptoms, or a diagnosis.Recommendations range from taking a comprehensive cardiac risk assessment, which can include an ECG heart screening, to consulting with a cardiology specialist to evaluate potential heart disorders that can lead to SCA.

Common Causes of SCA

Parent Heart Watch provides the following list of common causes of SCA:

Structural / Functional Causes
Arrhythmogenic Right Ventricular Dysplasia (ARVD) –
is a form of cardiomyopathy in which the heart muscle of the right ventricle is replaced by fatty-fibrous tissue. The scar tissue interrupts the normal smooth sequence of electrical activity that causes the heart muscle to contract, leading to arrhythmias. The weakened muscle will stretch, producing an enlarged right ventricle, which may not pump as effectively as a heart without ARVD. ARVD is often inherited.

Coronary Artery Abnormalities (CAA) – is an abnormality or malformation of the coronary artery, a blood vessel that supplies blood to the heart muscle. This condition is present at birth but can be silent for years until very vigorous exercise is performed. During exercise, blood flow to the heart muscle can be impaired and result in ventricular fibrillation.

Dilated Cardiomyopathy (DCM) – is the most common form of cardiomyopathy and occurs when heart muscle tissue is enlarged and stretched, making it difficult for the heart to function. DCM usually follows a viral infection.

Hypertrophic Cardiomyopathy (HCM) – is the second most common type of cardiomyopathy and results in excessive thickening of the heart walls, usually on the left side. The thickened heart muscle can block blood flow out of the heart and can increase the risk of ventricular fibrillation. In over half of the cases, this heart disorder is hereditary. HCM is the most common cause for sudden cardiac death in athletes in the United States.

Kawasaki Disease – is characterized by inflammation of blood vessels throughout the body including the coronary arteries of the heart. It often begins with a persistent high fever greater than 102°F, often as high as 104°F, which typically lasts at least 5 days and does not usually go away with normal doses of acetaminophen (Tylenol) or ibuprofen.

Marfan Syndrome – is an inherited abnormality of the connective tissue (ligaments and tendons) in the body. The wall of the aorta, the main artery from the heart, can become weak and rupture, especially during exercise. Often, affected people are tall and thin with long arms, legs, fingers and toes.

Mitral Valve Prolapse (MVP) – is a disorder that affects one of the heart’s valves — the mitral valve. The mitral valve doesn’t close properly allowing backward leaking of blood from the heart’s chamber. This may predispose some people to endocarditis, an infection of the heart valves and parts of the inside lining of the heart muscle, due to bacteria that adhere to the valve from dental work.

Myocarditis – is an inflammation of the heart muscle caused by either a viral, bacterial or fungal infection. It is often caused by the Coxsackie virus. It causes weakening of the heart’s pumping action and decreases its ability to supply oxygen-rich blood to the body. Most people recover from viral myocarditis with no ill effects. It is better not to participate in sports when a fever, chills and muscle aches are present, or symptoms which are indicative of a bad cold.

Electrical Causes
Brugada Syndrome – is an abnormality of the heart cells that disrupts the electrical activity in the heart and can cause life-threatening heart rhythms.

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) – is characterized by exercise or stress-induced ventricular arrhythmias in which the heart’s lower pumping chambers go into very rapid and uncontrolled rhythms that do not pump blood effectively.

Long Q-T Syndrome (LQTS) – is a disturbance of the heart’s electrical system. A genetic mutation causes a defect in the heart cells, called ion channels, which then prolongs the time the heart takes to electrically recharge after each heartbeat (known as the QT interval). LQTS is usually inherited. In other cases, LQTS can be caused by certain medicines, toxins, electrolyte disturbances, or other forms of heart disease.

Wolff-Parkinson-White Syndrome (WPW) – is a condition in which the normal electrical signals in the heart travel along an extra, abnormal electrical pathway. This condition can create a “short circuit” in the electrical system and lead to abnormally fast heart rates (tachycardia). WPW is sometimes inherited.

Other Causes
Commotio Cordis – is a condition that causes cardiac arrest if a sudden blow to the chest occurs at a critical point when the heart is electrically re-charging. It can occur with an impact of very little force. It is usually caused by a baseball, lacrosse ball, or a hockey puck despite the use of a chest protector. Chest protectors are designed primarily to protect a child from soft tissue damage and bone injury on impact; not as protection from the potentially fatal heart rhythm that can also occur as a result of impact. Wearing a chest protector, thus, creates a false sense of security. Commotio cordis is the second leading cause of death in young athletes while playing baseball, usually occurring between the ages of 7 and 16. Every child is vulnerable. Read more from the National Operating Committee on Standards for Athletic Equipment (NOCSAE).

Drugs or Stimulants – Even someone with a completely normal heart can develop ventricular fibrillation and die suddenly due to drug or stimulant use, which includes performance enhancing drugs, high-caffeine energy supplements, or diet pills.

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