Tuesday , March 18, 2014 - 1:02 PM
Runners suffered heart attacks in the Boston Marathon in April, the Myrtle Beach, S.C., Marathon in February, the New York and Philadelphia marathons last November and the Chicago Marathon last October. These incidents sparked renewed interest in possible links between distance running and heart failure.
The problem isn't new. The very first marathon runner, Phidippides, is believed to have dropped dead of a heart attack at the end of his run (although some early accounts attributed his demise to an altercation with the god Pan). Phidippides in 490 BC ran the 25 miles from the battlefield at Marathon to Athens to tell of the great victory won over the invading Persian army.
(The official marathon distance of 26 miles, 385 yards was established in 1908 so that the race in that year's Olympic Games would finish precisely in front of the box where Britain's royal family sat.)
More marathoners are suffering heart attacks, but that's because there are more marathoners, concluded a study published in the New England Journal of Medicine in January. The risk of heart attack from distance running isn't increasing.
Still any death from a recreational event is a concern and several studies are under way to better understand what goes on with the heart during endurance races.
Overall, the heart attack risk is very small. The New England Journal study, conducted by researchers from Massachusetts General Hospital, covered 10 years and nearly 11 million runners. Fifty nine suffered cardiac arrest during a race -- about 1 out of every 184,000 marathoners.
Of these, 42 (71 percent) were fatal. But this compares favorably with the overall fatality rate of 92 percent for out-of-hospital heart attacks.
Of the 59 heart attack patients, 51 were men, with an average age of 42. Unsurprisingly, most of the events occurred near the finish line.
But marathon running may trigger a cascade of potentially heart-damaging events, according to a study published last October in the American Journal of Cardiology.
Researchers affiliated with McLean Hospital in Belmont, Mass., an affiliate of the Harvard Medical School, analyzed the blood of marathoners less than a day after they'd finished a race. They found abnormally high levels of inflammatory and clotting factors of the kind known to be precursors for heart attack.
For this study, Arthur Siegel, director of internal medicine at McLean Hospital, and associates studied 80 physicians who ran in one or more of five Boston Marathons. Their average age was 47, all had run marathons before. The researchers drew blood the day before the race, within hours of finishing, and the day after.
Normally, blood maintains a balance between blood clotting and blood thinning (fibrinolytic) factors. The balance was maintained in marathoners before and just after the race, the researchers found. But on the morning after, clotting and inflammatory factors were elevated.
None of the runners he studied suffered cardiac arrest during or after their races, so Siegel thinks a second event is required to trigger a heart attack.
"No one really understands how the heart reacts during a marathon," said Vanessa Franco, 29, a marathoner who has a Ph.D. from Pitt in neuroscience, and who will earn her M.D. by the end of the year. She and fellow researchers Clifton Callaway and Dave Hostler are interested especially in "how the heart responds in the first few miles vs. last few miles," Franco said.
They recruited 10 volunteers, age 25 to 58, to wear monitors that measure the heart's electrical activity during a marathon in Pittsburgh May 6.
The volunteers wore the heart monitors for a day before the race to establish a baseline EKG. A resting EKG was taken when each completed the race. Additional EKGs were taken the day after, and five days after.
All the volunteers completed the race without incident, in times ranging from three to six hours.
The researchers have yet to analyze the data from the heart monitors worn during the race, Franco said. But the mere fact they have it fulfilled a key goal.
"We wanted to see if we could get good quality recording throughout the marathon, and we did," Franco said.
So now they can expand their pilot project to other marathons. They need data from many more marathoners to have a statistically valid study.
(Contact reporter Jack Kelly at firstname.lastname@example.org)
(Distributed by Scripps Howard News Service, www.scrippsnews.com.)
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