Sudden Cardiac Arrest

Sudden Cardiac Arrest (SCA) is a condition in which the heart suddenly and unexpectedly stops beating, mostly during or immediately after exercise. When this happens, blood stops flowing to the brain and other vital organs, and the person collapses. 

SCA is usually an electrical problem where the heart loses proper rhythm, causing the heart to quiver instead of pumping blood to the brain and body. This is called “ventricular fibrillation” or “V-Fib”.

Since the heart suddenly stops pumping blood to brain and body, the athlete quickly collapses, loses consciousness, and ultimately can die unless normal heart rhythm is restored using a defibrillator (usually an automated external defibrillator or AED).

The University of Maryland Children’s Heart Program, in collaboration with the PJ Schafer Foundation, has started “SAFER” clinics (Screening Athletes and Families for Exercise Related Risk). We provide comprehensive evaluation of young athletes to determine their risk of SCA and provide treatment, counseling and ongoing care to those athletes who are identified at risk.

Appointments can be made by calling 410-328-4FIT (4348).

Q: How common is Sudden Cardiac Arrest (SCA) in student athletes?


Fortunately SCA in student athletes is very rare.

Given increased demands on the heart during exercise, the risk of SCA in high school student athletes is nearly four times that of student non-athletes.

The chance of SCA occurring to any individual student athlete is about one in 100,000 per year.

Male student athletes are five times more at risk than female student athletes for SCA. It is more common in African-Americans than in other races and ethnic groups. Sports with the highest risks of SCA include football, basketball, swimming, lacrosse, baseball, cheerleading, track and cross-country.

Q: What are the most common causes of Sudden Cardiac Arrest in student athletes?


SCA is caused by several cardiovascular abnormalities and electrical diseases of the heart.

These conditions and diseases predispose an individual to have an abnormal heart beat or rhythm disturbance (arrhythmia) called ventricular fibrillation/V-Fib. This rhythm is fatal if not treated within a few minutes.

Most diseases and conditions responsible for SCA in children are inherited, which means the tendency to have these conditions is passed from parents to children through the genes.

While in some cases the cause of SCA is never determined, below are some conditions that may trigger SCA.  

  • The most common cause of SCA in an athlete is hypertrophic cardiomyopathy, also called HCM. HCM is a disease of the heart with abnormal thickening of the heart muscle.
  • The second most common cause is congenital abnormalities of the coronary arteries (blood vessels that supply blood to the heart).  This means that these blood vessels are connected to the main blood vessel of the heart in an abnormal way. Although this is not inherited, it is present from birth.
  • Other diseases of the heart that can lead to SCA in young people include:
    • Myocarditis: an acute inflammation of the heart muscle (usually due to virus). It is not inherited.
    • Disorders of heart electrical activity (mostly inherited except as stated).
      • Long QT syndrome: inherited electrical disease of the heart. It affects 1 in 3,000-5,000 individuals. In many cases abnormal heart beat is triggered by intense physical activity, swimming, strong emotions and loud noises.
      • Wolff-Parkinson-White (WPW) syndrome: extra conducting fiber in heart’s electrical system causes a rapid heartbeat. It is not inherited, with rare exceptions.
      • Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT): inherited electrical disease of the heart affecting 1 in 10,000 individuals. Physical and emotional stress can trigger rapid heart beat.
  • Arrhythmogenic Right Ventricular Cardiomyopathy (ARVD) and Brugada syndrome
  • Marfan syndrome, again an inherited disorder that affects heart valves, walls of major arteries, eyes and the skeleton.
  • Other cardiomyopathies such as dilated cardiomyopathy (an enlargement of the heart).
  • Congenital aortic valve abnormalities
  • Commotio Cordis, a concussion of the heart from a blow to the chest.
  • Use of recreational and performance enhancing drugs can also cause SCA.

Q: Are there any warning signs to watch for?


The following may be warning signs of potential heart issues and need to be further evaluated by an appropriate medical provider before engaging in further athletic activities. Most of these symptoms are more concerning when they occur during exercise.

  • Fainting, seizures or convulsions during physical activity
  • Fainting or a seizure from emotional excitement, emotional distress or being startled
  • Dizziness or lightheadedness, especially during exertion
  • Chest pain during exertion that does not increase with breathing or motion
  • Palpitations: awareness of the heart beating unusually during athletics or during cool down periods after athletic participation, especially if associated with other symptoms such as dizziness
  • Extreme tiredness or  shortness of breath associated with exercise

Q: What should be done in case of such an emergency or if someone witnesses Sudden Cardiac Arrest?


Time is most critical and prompt action is crucial to increase survival rates.

  1. Immediately suspect and recognize SCA: SCA should be suspected in anyone who has collapsed and is unresponsive. SCA is recognized by absence of normal breathing and pulse in an unresponsive athlete.
  2. Urgent use of an AED (automatic external defibrillator): Single greatest determinant of survival after SCA is the time from collapse to defibrillation or use of an AED.
    • Immediately call 911 and activate EMS.
    • CPR should be started immediately.

Q: What can we do to minimize the risk of SCA and improve outcomes?


The risk of SCA in student athletes can be minimized by both primary and secondary prevention strategies. Primary prevention is identification of at-risk athletes and providing them appropriate treatment and counseling with activity restriction before they have a serious event. Despite our best screening and prevention efforts, SCA may still occur. This is because some diseases are difficult to uncover and others can develop following a normal screening evaluation, such as an infection of the heart muscle from a virus.  Therefore effective secondary prevention or resuscitative efforts are equally important.

  1. One important strategy is the requirement for a yearly pre-participation screening evaluation, often called a sports physical performed by the athletes’ medical provider. It is very important that you carefully and accurately complete the personal history and family history section of the “Pre-Participation Physical Evaluation Form” available at
  2. Since the  majority of these conditions are inherited, be aware of your family history especially if any close family member:
  3. Take seriously the warning signs and symptoms of SCA. Athletes should notify their parent, coach or school nurse if they experience any of these warning signs or symptoms.
  4. Schools in Maryland have AED policy and emergency preparedness plan to address SCA and other emergencies in schools. Be aware of your schools various preventive measures.
  5. If a cardiovascular disorder is suspected or diagnosed based on the comprehensive pre-participation screening evaluation, a referral to a child heart specialist, i.e. a pediatric cardiologist, is crucial.

Q: Who should be screened for assessing the risk for SCA?


All school athletes should be evaluated and screened by their primary care provider at least once a year as detailed above. This process also called “pre-participation screening” or “sports physical” involves parents and student athletes answering specific questions about symptoms during exercise and questions about family health history. It is very important that you carefully and accurately complete the personal history and family history section of the form. The annual physical examination includes measurement of blood pressure and careful listening to the heart, especially for murmurs or rhythm abnormalities.

Q: When should a student athlete see a heart specialist?


If a cardiovascular disorder is suspected or diagnosed based on the comprehensive sports physical, it is critical to refer a child to a pediatric cardiologist or heart rhythm specialist experienced with the pre-disposing heart condition identified during the exam.

It is always better to err on the side of caution, so if the family or the provider has any concerns, a referral should be made.

Q: What is an AED?


An AED is a portable medical device that analyzes the heart rhythm and prompts the user to delivers a shock when necessary to return the heart to a normal rhythm.

These devices only require the user to turn the device on and follow the audio instructions when prompted.

Q: Can commonly available AEDs be used for kids?


Commonly available AEDs can be used in everyone over eight years old and weighing more than 55 lb.  AEDs with pediatric defibrillation capability are preferable in kids under age 8 and weighing less than 55 lb. However, even if a pediatric AED is not available, bystanders should not hesitate to use an adult AED to help reset the child’s heart. Using any AED can only help with survival.

To make an appointment with the Children's Heart Program, please call 410-328-4FIT (4348) (patients) or 1-800-373-4111 (physicians).

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