Examining Runners And Cardiac Arrest

“Physiologically, the body only has enough carbohydrate storage for about 20 miles,” Dr. DuPrey said. “It takes so much out of you to do more than 20 miles in training. I’m not sure if there’s any way around that.”

This is just part of our coverage of this year's Philadelphia Marathon. You can read all of the articles at  www.philly.com/marathon2012. And don't forget to join us there on race day to follow the action.

By Robert Senior

Last year’s marathon here in Philadelphia saw two runners collapse mere yards from the finish line. Both were later pronounced dead due to sudden cardiac arrests. While such occurrences in marathons are quite rare, obviously even one is too many. 

With that in mind, Kevin M. DuPrey, D.O., a family practitioner at Crozer Keystone Health System in Springfield, Pa., set out to get some answers.

Starting in 2010, Dr. DuPrey and his associates began a study that would come to examine 1.7 million marathon runners dating as far back as the mid-1970s.They were looking for any similarities in the few such instances of cardiac arrest on the books.

A former cross-country and track and field athlete at the University of Delaware and a two-time competitor in the Philadelphia Marathon, Dr. DuPrey had a keen personal interest in the outcome. “Sudden cardiac arrest is certainly the most devastating consequence that can happen in an endurance event,” he said. “I wanted as much information as possible about that.”

The study included marathon runners in the United States from 1976-2009 and found only 30 instances of sudden cardiac arrest (SCA). That’s about one instance for every 57,000 runners. The focus quickly shifted to finding trends or links between those competitors who were affected.

Some key statistics set forth by the research:

  • An overwhelming majority (28 out of 30; 93 percent) of runners who suffered SCA were male.
  • The average age of competitors reported in such incidents was 49.7 years, but runners as young as 19 and as old as 82 were among the instances reported.
  • More than half (53 percent) of SCA occurred from the 23-mile mark and on, or the last four miles of the event.

Of the 30 cases, 10 victims passed away as a result of the SCA. Upon autopsy, seven of those deaths were found to be the result of coronary artery disease.

In terms of prevention, the study found that automated external defibrillator (AED) use correlated highly with survival. AEDs are portable electronic devices with the ability to diagnose life-threatening implications of cardiac arrhythmias, and are able to treat such incidents through defibrillation.

Dr. DuPrey found very strong evidence that AEDs are often life-savers for affected marathon runners:

  • Of the 20 cases where the competitor survived, 17 had an AED placed during the SCA.
  • Conversely, the 10 reported deaths only saw three instances where an AED was utilized.

“That was our biggest correlation to survival—the use of the defibrillator,” he clarified.

As for the large number of instances in the final four miles, Dr. DuPrey said that since even the longest training runs for marathons typically only last 20 miles, those final six miles of the race enters ‘uncharted territory’ so to speak. “Physiologically, the body only has enough carbohydrate storage for about 20 miles,” he said. “It takes so much out of you to do more than 20 miles in training. I’m not sure if there’s any way around that.”

Dr. DuPrey and his team made two primary recommendations after concluding their research. First, individuals who plan to run a marathon or any endurance race should be evaluated by a physician for risk factors for coronary artery disease or SCA. “There are some obvious red flags, like chest pain on exertion,” said Dr. DuPrey. “Anyone with symptoms should undergo further testing.”

But perhaps the most important recommendation was relevant to event planning and preparation on the part of race organizers. “You need to have AEDs placed throughout the race course, with a focus on those last four miles where the majority of sudden cardiac arrests occur,” he concluded.