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Bigger Hearts OK for Elite Athletes?

Study: No Extra Heart Risks Seen in Athletes With Big Left Atrium of Heart
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WebMD Health News

Aug. 16, 2005 -- New research shows that in world-class athletes, an enlarged heart may not raise the risk of heartbeat problems.

Specifically, researchers looked at the heart's upper left chamber (the left atrium) in more than 1,700 competitive athletes.

They found that relatively few athletes had left atrial enlargement and that the condition didn't raise the odds of having an irregular or abnormally fast heartbeat called atrial fibrillation.

But most of us are nowhere near that level of athletic achievement. It's always wise to get any heart concerns checked out by a doctor and to follow medical advice about heart care.

The study appears in the Journal of the American College of Cardiology. The researchers included Antonio Pelliccia, MD, of the National Institute of Sports Medicine with the Italian National Olympic Committee.

Supersized Hearts

The heart of athletes undergoes changes during training. In well-conditioned athletes these common structural and electrical changes are known as the athletic heart syndrome.

In atrial fibrillation blood isn't completely pumped out of the upper chambers of the heart. Blood that doesn't circulate pools in the chamber and can clot. If the clot travels, leaving the heart, it can block arteries in the brain, causing a stroke.

The stats on the study's athletes:

  • Men: 71%
  • Average age: 24
  • Average time in vigorous training: 6 years
  • Players in the Olympics or world championships: 390

The other athletes in the study had participated in national and regional competitions. All were screened between 1992 and 1995. The findings:

  • Most didn't have enlarged hearts or heartbeat problems.
  • 24% (347 athletes) had a heart with an enlarged left atrium.
  • Less than 1% of the entire group had irregular or abnormally fast heartbeats.
  • Those with an enlarged left atrium weren't more likely to have irregular or abnormally fast heartbeats.

In 2003, the researchers checked in with the athletes who had had enlarged left atria and no other heart problems. The "vast majority" was still training and competing as hard as ever, and "virtually all" were healthy and had no heart problems, write the researchers.

How Big Is Big?

An enlarged left atrium was 40 millimeters or bigger. Only 2% of the athletes had a left atrium that was 45 millimeters or bigger. The upper range was 46 millimeters in women and 50 millimeters in men.

That might be the "outer limit" of exercise's effect on heart size, and enlargements beyond that might stem from health problems, write the researchers.

Chalk It Up to Training?

The heart's left atrium probably got bigger in response to intense athletic conditioning, note the researchers.

"Left atrial remodeling in competitive athletes may be regarded as a physiological adaptation to exercise conditioning, largely without adverse clinical consequences," they write.

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