Participating in Marathons Not Likely to Increase Risk for Cardiac Arrest

A recent study published in the January 12 issue of the New England Journal of Medicine found that most participants in marathons and half-marathons who experienced cardiac arrest during the race or at the finish line had an undiagnosed, pre-existing heart condition.

According to a press release, the researchers identified 59 cases of cardiac arrests that occurred between 2000 and mid-2010 during all US half and full marathons. Study participants, either the survivor or the next of kin, were interviewed for demographic data, personal and family medical histories, cardiac risk factors or previous diagnoses and information about the cardiac event. Complete medical records and autopsy data were analyzed when possible.

Of the 59 cases, 40 occurred at full marathons, 19 occurred at half marathons and 42 were fatal. More than 85% took place in men. Of the 31 affected runners for whom the researchers had medical records, 23 had died. Fifteen of those had definite or probable hypertrophic cardiomyopathy — an abnormal thickening of the heart muscle — and nine had additional cardiac abnormalities. While hypertrophic cardiomyopathy is the most common cause of cardiac death in young athletes, the risk has not previously been considered as an issue in the older running population.

Rapid initiation of CPR was a main factor in survival. Among the survivors, underlying coronary artery disease was the dominant pathology, but no participants had evidence of acute coronary plaque rupture.

“The lack of plaque rupture — a critical event in many heart attacks — was an intriguing and surprising find. It suggests that the kind of underlying disease that causes cardiac arrest in distance runners may be detectable by a simple stress test prior to race day,” senior study author Aaron Baggish, MD, director of the cardiovascular performance program in the Massachusetts General Hospital division of cardiology, stated in the release. “Our next steps are to investigate strategies for pre-race runner education and heart disease screening and to study the contribution of specific risk factors in more detail. A big take-home message of the study is the importance of bystander CPR, which is a relatively simple skill that can be learned by everyone in the community. Recognition of this important finding calls us to action, and we will be offering the first-ever CPR education session for runners, family members and spectators at this year’s Boston Marathon.”

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