Sudden Cardiac Death in Athletes
Frequently asked questions related to sudden cardiac death from Steven J. Keteyian, Ph.D.
What is a sudden cardiac death in athletes and why does it now appear to be of much greater interest than in years past?
Just as the name implies, sudden cardiac death during or soon after exercise in competitive athletes is a catastrophic event that continues to be highly visible, compelling, and associated with much public emotion. In some ways sudden cardiac death (SCD) seems counter-intuitive, in that people who appear to be quite healthy and able to exercise should not be likely candidates for such a tragic event.
SCD is known to occur in athletes of both genders, although it is more common in men than in women. Also, SCD can occur while participating in any sport but is more common in basketball and football in the United States and soccer in Europe.
What is the incidence or frequency of SCD in athletes?
The incidence of SCD is quite rare. In fact, among the 10-15 million athletes (high school, college, professional, older adult) participating in organized competitive sports in the United States, SCD occurs in less than 300 athletes each year. This data converts to an event rate of approximately 1 death per every 50,000 athletes.
What is the underlying cause(s) of sudden cardiac death in athletes and does the underlying cause differ based on age?
In general, SCD in persons greater than 35 years old is most often due to a heart attack or irregular heart rhythm caused by a blockage in one ore more of the arteries (coronary arteries) that supply blood to the heart. This blockage is due to atherosclerosis and limits the amount of oxygen provided to heart tissue, which is especially worrisome when somebody is exercising and the heart is demanding more oxygen. The factors responsible for the development of atherosclerosis are those we are well familiar with, including high blood pressure, elevated cholesterol levels, inactivity, cigarette smoking, diabetes, obesity and family history.
Among individuals less than 35 years of age, the likely cause of SCD is either congenital or genetic. In these cases the athletes most often have no knowledge of their condition and there is nothing they could have done to prevent it. These abnormalities include an abnormally enlarged heart, which is prone to a life-threatening and irregular heartbeat; an abnormality in the development of the muscle cells within the heart; the abnormal development of the arteries that supply blood and oxygen to the heart; and other less common but equally important problems. The above conditions develop regardless of whether the person was an athlete or sedentary. Unfortunately, in athletes, the heart is called upon to work harder during exertion; therefore, its ability to perform is challenged because of these congenital or genetic abnormalities.
What type of screening is available or should be performed to help identify athletes that might be at increased risk for SCD during exercise?
Most athletes involved in competitive sport programs at the high school, college and professional levels usually undergo some type of pre-participation examination conducted by a health care professional to “clear” them for participation. This examination usually includes a comprehensive series of questions about their own medical history, including asking about any symptoms that might indicate a heart problem (e.g., extreme shortness of breath, dizziness, blacking out, chest pain or palpitations), as well as questions that pertain to the health of family members. In addition to these interview questions, a brief examination is also performed that allows the health care professional to screen for blood pressure and potential heart abnormalities. The above interview and examination are almost always adequate to screen for the presence of any heart-related concerns that might place an athlete at risk for SCD.
Increasingly common over the past several years is the use of resting ECGs to also assist with screening for cardiac abnormalities that suggest increased risk for SCD. The use of the ECG in this fashion is more popular in Europe (e.g., Italy) than the United States, and part of the reason for the geographical discordance is that the use of ECG to help screen for SCD-related abnormalities is itself controversial. As mentioned above, SCD is quite rare and almost equally as rarely are subtle variances found on the resting ECG. Because these normal variances are noted, additional testing is ordered and it becomes necessary to withhold the individual from athletics until it is proven that, in fact, all findings are normal, which is almost always the case.
So there is no mistake, exercise is a healthy behavior that all children and adults should participate in. Doing so improves quality of life, physical fitness, and lessens one’s risk for many catastrophic diseases such as certain cancers, heart disease and diabetes. For the 10-15 million people in the United States who compete athletically, it is true that among these individuals each year there will be the rare occurrence of SCD. To help lessen or avoid these tragic events from occurring, high school, college and professional athletes should undergo a pre-participation examination, and those screening programs may or may not include a resting ECG.