Life-Threatening Events During Endurance Sports: Is Heat Stroke More Prevalent Than Arrhythmic Death?

Study Questions:

What percentage of life-threatening events during endurance races is due to heat stroke, and what percentage is due to cardiac causes?


In a retrospective study, all popular long distance races that took place in Tel Aviv, from March 2007 to November 2013, were examined. The number of athletes at risk was known, and the number of athletes developing serious sport-related events and requiring hospitalization was known. Life-threatening events were defined as those requiring mechanical ventilation and hospitalization in intensive care units.


Overall, 137,580 runners participated in long distance races during the study period. There were only two serious cardiac events (one myocardial infarction and one hypotensive supraventricular tachyarrhythmia), neither of which were fatal or life threatening. In contrast, there were 21 serious cases of heat stroke, including two that were fatal and 12 that were life threatening. One of the heat stroke fatalities presented with cardiac arrest without previous warning.


In this cohort of athletes participating in endurance sports, there were 10 serious events related to heat stroke for every serious cardiac adverse event. One of the heat stroke–related fatalities presented with unheralded cardiac arrest. The authors concluded that these results put in a different perspective the ongoing debate about the role of preparticipation electrocardiographic screening for the prevention of sudden death in athletes.


Arrhythmic death and heat stroke represent two important causes of sudden death during endurance races. Although arrhythmic death (associated with proven or presumed underlying structural heart disease) has been the topic of intense debate regarding best practices for screening and prevention, this study suggests that heat stroke might be a much more common condition, at times masquerading as arrhythmic death. The relative rates of various sports-related events can be expected to vary by population, affected by age and genetics as well as race conditions. Although this study will not settle the debate regarding athlete screening, it provides important new data.

Clinical Topics: Arrhythmias and Clinical EP, Sports and Exercise Cardiology, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Athletes, Myocardial Infarction, Intensive Care Units, Respiration, Artificial, Sports, Death, Sudden, Cardiac, Tachycardia

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