Life-threatening events during endurance sports: Is heat stroke more prevalent than arrhythmic death?

Background Two important causes of sudden death during endurance races are arrhythmic death and heat stroke. However, "arrhythmic death" has caught practically all the attention of the medical community whereas the importance of heat stroke is less appreciated. Objectives The study sought to determine what percentage of life-threatening events during endurance races are due to heat stroke or cardiac causes. Methods This retrospective study examined all the long distance popular races that took place in Tel Aviv from March 2007 to November 2013. The number of athletes at risk was known. The number of athletes developing serious sport-related events and requiring hospitalization was known. Life-threatening events were those requiring mechanical ventilation and hospitalization in intensive care units. Results Overall, 137,580 runners participated in long distance races during the study period. There were only 2 serious cardiac events (1 myocardial infarction and 1 hypotensive supraventricular tachyarrhythmia), neither of which were fatal or life threatening. In contrast, there were 21 serious cases of heat stroke, including 2 that were fatal and 12 that were life threatening. One of the heat stroke fatalities presented with cardiac arrest without previous warning. Conclusions In our cohort of athletes participating in endurance sports, for every serious cardiac adverse event, there were 10 serious events related to heat stroke. One of the heat stroke-related fatalities presented with unheralded cardiac arrest. Our results put in a different perspective the ongoing debate about the role of pre-participation electrocardiographic screening for the prevention of sudden death in athletes.