Running long-distance races such as marathons and half marathons has become more popular in recent years, and reports of sudden death or cardiac arrest during these events are highly publicized. Using the Race Associated Cardiac Arrest Event Registry, researchers examined data on cardiac arrests associated with long-distance races from 2000 to 2010 to determine the overall incidence rates of cardiac arrest and sudden death during these events and the characteristics of the affected participants.

Cases of cardiac arrest were identified through multiple public record searches. The researchers mailed letters to the survivors and the next of kin of nonsurvivors to obtain more detailed medical information.

An estimated 10.9 million runners participated in long-distance races over the 10-year study period. In that time, a total of 59 cardiac arrests occurred, yielding an overall incidence of one per 184,000 runners. Forty of the 59 cardiac arrests occurred during or after marathons; 19 occurred during or after half marathons. Eighty-six percent of the cardiac arrests were in men; the mean age was 42 years. Also, the rate of cardiac arrest in men rose over the last five years of the study (2.03 per 100,000 runners), compared with the first five years (0.71 per 100,000).

Forty-two (72%) of the 59 runners who experienced cardiac arrest didn't survive, an incidence rate of one death per 259,000 runners (mean age, 39 years). Data regarding the cause of the cardiac arrest were available for 31 runners, 23 of whom died. Among the nonsurvivors, hypertrophic cardiomyopathy or possible hypertrophic cardiomyopathy was most frequently implicated as the cause of death (15 of 23).

Among survivors, the most common cause of cardiac arrest was ischemic heart disease (five of eight). Early bystander-initiated CPR and an underlying diagnosis other than hypertrophic cardiomyopathy were significantly associated with survival.

Although the risks of cardiac arrest and sudden death during races involving long-distance running were low in comparison with other forms of high-exertion exercise, runners with underlying hypertrophic cardiomyopathy and slightly older men running in marathons are the most vulnerable. On-site health care professionals and bystanders can help increase the odds of survival through the prompt initiation of CPR.-AK

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