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When the American swimmer Dana Vollmer won Olympic gold in 2004 and 2012, she was going against the advice of leading cardiology groups. At 15, she had been diagnosed with a condition that could cause her heart to stop during intense exercise, but she decided to take the risk and keep swimming anyway.

Now, new recommendations out Monday from the American Heart Association and the American College of Cardiology support Vollmer’s decision. The revisions reflect research showing that heart conditions once thought to be unsafe on the field or in the pool may not be as dangerous as previously thought. STAT explains what’s changed.

How often do athletes die on the field?

Rarely. Every year, sudden cardiac death affects only one to three young athletes per 100,000. But that’s still nearly three times as often as for non-athletes.


Athletes are at greater risk because of their intense physical workouts. And whenever an athlete dies suddenly, “it’s a heart-wrenching, emotionally draining event — and nobody wants to see it happen,” said Dr. Douglas Zipes, a cardiologist at the Indiana University School of Medicine who co-chaired the committee that drafted the new guidelines.

What’s different about the new recommendations?

The last time the two heart groups put out a scientific statement for competitive athletes with cardiac problems, in 2005, they were much more conservative about who should keep competing. “If a patient had a heart disease of any sort for which there was any chance of sudden death, then the most prudent thing to do was to kick them out — at least that is what the expert opinion was,” said Dr. Michael Ackerman, a Mayo Clinic cardiologist and one of the authors of the new guidelines. But there has been a movement away from always telling athletes with heart conditions to give up the game. “That may not always be the best idea for that athlete in terms of mind-body-soul health,” Ackerman said.


The 2005 guidelines recommended that those with implanted defibrillators or pacemakers should quit playing competitive sports. Now, those athletes may be able to stay on the roster if they have discussed the risks with their physicians. Same goes for those with certain rhythm disorders of the heart, such as long QT syndrome, the condition that Dana Vollmer has lived and swum with for decades. But many of the recommendations from 2005 remain unchanged. Patients with hypertrophic cardiomyopathy — a thickening of the heart muscle that is the most common cause of sudden death in athletes — are still thought to be too vulnerable to cardiac events for them to play competitive sports.

What new evidence prompted the changes?

One 2013 study found that, of 372 athletes with implanted defibrillators, not a single person died because of a heart rhythm problem. Nor did any of them have to be shocked back to life by an external defibrillator. Some of their implanted devices had to kick in, but those shocks were no more common during competitive sports than they were during everyday physical activity.

Another, led by Ackerman in 2012, found that of 130 athletes who kept competing despite their long QT diagnosis, only one had a cardiac event — even fewer than among non-athletes.

Will the new guidelines affect athletes’ lives?

The guidelines are not officially binding, but they do determine whether athletes can keep competing. To enroll in high school and college sports, an athlete needs a doctor’s signature, and many physicians are loath to sign against the guidelines’ recommendations.

And in spite of the medical jargon, many proactive patients read these recommendations themselves, trying to figure out how the information might apply to their own lives. “I probably get more than 100 inquiries that relate specifically to the guidelines each year,” said Dr. Lawrence Creswell, a cardiac surgeon at the University of Mississippi Medical Center.