Marathon Runners Have Low Risk of Cardiac Arrest

Reports of runners suffering cardiac arrests during long-distance events have led to questions about the overall safety of these activities. However, a new study looking at data on over 10 million runners of marathons and half-marathons has found that participating in these events is associated with a low risk of cardiac arrest compared with other athletic activities.
 
The study included 10.9 million runners who participated in marathons and half-marathons from 2000 to 2010, of whom 59 experienced a cardiac arrest. Those suffering cardiac arrest had a median age of 42, and 51 of them were men. The overall incidence rate was 0.54 per 100,000 participants, with a significantly higher rate during marathons (1.01 per 100,000) than half-marathons (0.27 per 100,000) and among men (0.90 per 100,000) than women (0.16 per 100,000). Of the 59 cardiac arrests, 42 (71%) were fatal—significantly lower than the 92% general fatality rate for cardiac arrests that occur outside a hospital. (The researchers note that this is most likely due to the availability of prompt medical attention from spectators and on-site personnel.)
 
The researchers were able to obtain detailed medical information for 31 of the runners who experienced cardiac arrest, 23 of whom died as a result. Of those who died, 15 had definite or probable hypertrophic cardiomyopathy (which is frequently implicated in the death of young athletes), and nine of these had an additional cardiac risk factor, such as obstructive coronary disease. Among the runners who survived a cardiac arrest, underlying coronary artery disease was the dominant pathology. Factors most strongly linked to survival were swift application of CPR by bystanders and lack of hypertrophic cardiomyopathy.
 
The study appears in the January 12 edition of the New England Journal of Medicine.