Heart attack deaths during marathons decline significantly, study reveals

While more people than ever are running marathons in the U.S., the risk of dying from a heart attack during a run has fallen dramatically in recent years. That's a key conclusion from a new study by Jonathan Kim, associate professor in the Emory School of Medicine. Kim's research is a follow-up to a study he published in 2012 – the first investigation into unexpected cardiac arrests during long distance running events.

The new findings, published in JAMA, indicate that while the rate of marathon runners who suffer cardiac arrests remained unchanged, their chance for survival is twice what it was in the past. Now, far fewer marathon runners who suffer cardiac arrest are dying of it.

We continue to see media reports about unfortunate cases of cardiac arrest during long distance running events. But, has the incidence of these events changed? Have there been changes in the most common causes of cardiac arrest? What are the factors associated with death and survival? It was a novel question to ask 13 years after our first analysis, and an important one because recreational running continues to increase in popularity."

Jonathan Kim, associate professor, Emory School of Medicine

The challenge of finding data

More than 29 million people completed marathons in the U.S. between 2010 and 2023, triple the number of the previous decade, which Kim examined in his first study. There's no central registry of race-related cardiac events, so for both studies, his team had to find their data through a range of sources, starting by contacting individual race directors.

"We leveraged a few sources including a comprehensive review of media reports," Kim says. "We also had contact information for all race directors and were able to reach approximately 70% of them who helped and told us the number of events during this specific timeline, including if the individual died and the sex of the participant."

The researchers used extensive public internet searches to identify and reach out to runners who survived cardiac arrests, or next-of-kin, to construct detailed profiles of as many cases as possible. "The vast majority of cases were identifiable by public search engines. And all of the deaths were as well," Kim says.

Analyzing this extensive database, Kim found that while the rate of cardiac arrests was about the same during the two periods – .60 per 100,000 participants now versus .54 per 100,000 participants in the earlier period – the rate of deaths from these cases, however, fell by half: from .39 per 100,000 to .19 per 100,000. That's about a 50% decline in the death rate since 2000-2009. As before, cardiac arrests remained far more common among men than among women and more common in marathons than half marathons.

The sport's growing awareness of cardiac death risk

What led to the dramatic change in death rates? Kim thinks the whole sport has become more aware of the risks and of the need to have emergency services available to runners, a conclusion he reached after interviewing as many survivors as he could find. "What we found was that every one of those people got hands-on cardiopulmonary resuscitation, but the vast majority also had immediate access to an automated external defibrillator. That's the difference," he says.

That survival rate is comparable to the cardiac arrest survival rate in other public places that now make defibrillators routinely available such as airports and casinos, which have seen similar declines in deaths.

Kim says his findings offer additional evidence of how important it is to make CPR training available to race participants and to strategically place defibrillators along the racecourse. It's also important, he says, to better identify the most vulnerable in a population before they run a race.

"These are more often potentially preventable events," Kim says. "Being able to identify people, more commonly older individuals with unrecognized cardiovascular risk factors, doesn't mean they can't run a race. Rather, it affords the opportunity to improve primary preventive cardiovascular care and potentially further reduce the risk of cardiac arrest during these events. The incidence of sudden cardiac arrest during long-distance races hasn't changed in over 20 years. I think this is an important arena of future research."