Many top cyclists have enlarged hearts
2004-07-15
NEW YORK (Reuters Health) - More than half of elite
professional cyclists apparently have an enlarged heart
chamber, a new study from France indicates.
Although endurance athletes are known to develop large
hearts, the finding that such a high percentage of
top-class cyclists are affected could have implications
for screening elite athletes for heart conditions,
researchers say.
Dr. Eric Abergel of the Hospital European Georges Pompidou
in Paris and colleagues examined the hearts of 286
cyclists who competed in the Tour de France in 1995 or
1998 or both years. The researchers used echocardiography,
which uses ultrasound to create an image of the heart, to
examine cyclists' hearts two days before the race.
As a comparison, 52 non-cyclists also underwent
echocardiography.
The dimensions of the left ventricle, the heart's main
pumping chamber, were much greater in cyclists than in
non-athletes. A little more than half of cyclists had a
substantially enlarged left ventricle, the researchers
report in the Journal of the American College of
Cardiology.
In about 12 percent of cyclists, the left ventricle was so
enlarged that it had an effect on heart function,
according to the report.
Typically, the heart wall thickens when a chamber
enlarges, but the researchers noticed something unusual
when they compared cyclists who competed in 1995 with
those who competed three years later. Cyclists in the 1998
race tended to have a larger left ventricle, but the walls
of the chamber were thinner than in 1995 cyclists.
Abergel and his colleagues are not sure why the 1995 and
1998 cyclists differed. Although performance did not vary
significantly between the years, the variations could
reflect excessive training or the use of steroids or other
performance-enhancing drugs, the authors suggest.
"This modification could be due not only to intensive
physical training but also to pharmacological training -
drug abuse," Abergel told Reuters Health.
It is uncertain whether the changes to the heart can be
harmful to cyclists, according to the French researcher.
Whatever the reasons for the enlarged hearts in elite
cyclists, the changes could make it more difficult to
detect certain heart problems, Abergel and his colleagues
suggest.
For example, a genetic disorder called hypertrophic
cardiomyopathy that causes the walls of the heart to
thicken and stiffen, can cause sudden death.
Although the study does not prove that extreme exercise
causes an enlarged heart, "it is hard to ignore the
possibility that extreme amounts of exercise may cause
harm," according to Dr. Pamela S. Douglas of the
University of Wisconsin in Madison.
However, very few people train at the same level as riders
in the Tour de France, she notes in an accompanying
editorial.
"It appears that, even with exercise, one of the most
powerful strategies for good health and longevity is
moderation," Douglas concludes.
SOURCE: Journal of the American College of Cardiology,
July 7, 2004. - By Merritt McKinney
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