Can Competitive Sports Cause Sudden Cardiac Arrest?

A new Canadian study in the New England Journal of Medicine sheds light on whether or not a sudden cardiac arrest is a significant occurrence during competitive sports.

People with or without heart conditions often worry if they will have a sudden cardiac arrest (a sudden loss of heart function) while playing sports. Given that death is a possible outcome of cardiac arrest, their concerns are quite understandable.

Examining Six Years of EMS Cardiac Arrest Data

Does playing sports create a risk of sudden cardiac arrest for such people?  Researchers in the province of Ontario, Canada decided to find out. In a study published in the New England Journal of Medicine, these researchers examined almost six years of data (2009-2014) from the Rescu Epistry database, which is a provincial registry of all people who had a cardiac arrest outside of a hospital, and who were then treated by emergency medical services (EMS) personnel. The study carefully calculated the number of competitive and recreational athletes in the province using data from sporting organizations and census data.

The Incidence Rate of Sudden Cardiac Arrest

The researchers targeted persons in the registry who were between 12-45 years of age, who had a sudden cardiac arrest during, or within one hour after, a sporting activity. The incidence of sudden cardiac arrest was calculated using athlete-years. For example, each time the study included data for one athlete over one year, it was recorded as an athlete-year. This study included data from 2.1 million athlete years.

The key findings were:

1. The incidence of sudden cardiac arrest was 0.76 cases per 100,000 athlete-years for this population.
2. For competitive athletes, race events and soccer produced the highest number of sudden cardiac arrest cases, while for non-competitive athletes it was gym workouts and running.
3. For both competitive and non-competitive athletes younger than 35 years of age, arrhythmia (abnormal heart rhythm) was the greatest cause of sudden cardiac arrest, while for those athletes aged 35-45 years, coronary artery disease was the greatest cause.

Limitations: Study Based on the Rescu Epistry Database

The limitations of this study identified by the authors included:

1. Given that their analysis examined past results, the cause of death for some subjects in the Rescu Epistry database could not be identified with certainty.
2. There is the possibility that in the general population, some athletes at risk for sudden cardiac arrest may have already chosen not to participate in sports activities.  Thus, the incidence reported in this study may be higher than what was reported.
3. There is also the possibility that some competitive athletes may have suffered a sudden cardiac arrest while participating in recreational sports.  This would inadvertently lower the reported incidence of cardiac arrest during competitive sports.
4. Some athletes may have suffered a sudden cardiac arrest while resting, or at a time greater than one hour after the conclusion of the sporting event.  This limitation would give the impression of a lower risk.

Structural Heart Disease is an Uncommon Cause

The authors’ one definitive conclusion was that structural heart disease (an often congenital heart defect that does not affect the blood vessels in the heart) was an uncommon cause of sudden cardiac arrest due to participation in competitive sports.  In fact, sudden cardiac death during participation in competitive sports is rare, and the vast majority of cases would not have been identified through pre-screening. Thus, people with such issues should have some confidence in their ability to play sports, at least at a moderately competitive level. However, anyone with a heart issue should, of course, consult with their physician before considering participating in sports of any kind.

Written by Raymond Quan, MASc, MBA

Reference: Landry, C.H., Katherine S. Allan, K.S., Connelly, K.A., Kris Cunningham, K., Morrison, L.J., M.D., and Dorian, P., Sudden Cardiac Arrest during Participation in Competitive Sports, The New England Journal of Medicine, 377;20 (November 16, 2017).

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