DALLAS, July 18, 2000 -- The use of electrocardiograms (ECGs) to detect heart disease in competitive athletes has definite limitations and its results should be confirmed with other tests, according to a recent study of Italian Olympians published in today's Circulation: Journal of the American Heart Association.
An ECG measures the electrical impulses produced by the heart, drawing a graph that represents when the heart beats and rests. The 12-lead ECG is a simple, cost-effective test to detect cardiovascular abnormalities. It is part of the battery of tests used at the Institute of Sports Science in Rome, Italy, where all members of the Italian Olympic team are required to undergo an annual medical evaluation.
"Athletic conditioning is responsible for lots of changes in an athlete's ECG," says the study's lead author Antonio Pelliccia, M.D., a professor in the department of medicine at the Institute of Sports Science. "Just like any other muscle that is exercised regularly, changes in the heart muscle are likely to occur as a result of athletic training."
Pelliccia says highly trained athletes in particular may tend to have abnormal ECGs as compared to those of non-athletes. His study shows that abnormal ECGs were associated with conditions such as an enlarged heart or thickening of the heart wall that would usually indicate that the individual has a disease that is responsible for sudden cardiac death.
However, Pelliccia says these "abnormalities" may not necessarily indicate disease for athletes. When researchers looked at the structure of some athletes' hearts, they found structural malformations in a very small minority.
"It's important for us to know how reliable the ECG is for detecting whether the changes in an athlete's heart are life threatening," Pelliccia says.
During a two-year study researchers compared an echocardiogram, an ultrasound that shows the heart's structure, to an ECG for each of 1,005 competitive athletes. The echocardiograms showed cardiovascular abnormalities in 5 percent (53) of the athletes tested.
ECG patterns were "distinctly abnormal" in 14 percent of the athletes and "mildly abnormal" in 26 percent. Sixty percent of the athletes involved in the study had ECGs that were normal or showed only minor alterations that were considered typical of athletes' hearts.
Echocardiograms showed that 90 percent of the athletes with distinctly abnormal ECGs had an enlarged left ventricle, the heart's main pumping chamber, and increases in heart wall thickness. These athletes participated mainly in endurance sports such as rowing, cycling, long-distance running and cross-country skiing. Follow-up tests for this group over an average of three years showed no evidence of structural malformations.
"It is reasonable to assume that long-term, intensive athletic conditioning substantially alters the ECG in some athletes by as yet undefined mechanisms," says Pelliccia. "In practical terms, our research suggests that when a doctor sees an abnormal ECG in an athlete, further investigative tests such as an echocardiogram should be conducted to rule out actual structural abnormalities."
Athletes with abnormal ECGs were generally younger and male. Pelliccia says that a higher incidence of abnormal ECGs in athletes under 20 years of age suggests that intensive training is more likely to alter the ECG pattern when associated with the body's growth and maturation process.
The study showed that heart abnormalities were twice as common in athletes with distinctly abnormal ECGs (10 percent) compared to athletes with mildly abnormal ECGs (5 percent). The most common problems were related to mitral valve prolapse, where certain valves don't close properly as the heart pumps and a small amount of blood leaks backward. This group was evenly split between abnormal and normal ECGs.
The study also showed that female athletes were more likely to have normal ECGs than male athletes.
"This is likely due to several factors, including the mild structural changes induced by training in women and their lower participation in certain sports, such as rowing and canoeing, that have a substantial impact on ECG pattern," Pelliccia said.
The researchers are planning a study on the long-term effects of athletic conditioning on cardiovascular health in which they will call back athletes from the ECG study.
Co-authors of the study are Barry J. Maron, M.D.; Franco Culasso, Ph.D.; Fernando M. di Paolo, M.D.; Antonio Spataro, M.D.; Alessandro Biffi, M.D.; Giovanni Caselli, M.D.; and Paola Piovano, M.D.
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Media Advisory: Dr. Pelliccia can be reached by phone at 39-06-3685-9127; or by email at ISS_Medicina@coni.it or ant.pelliccia@libero.it (Please do not publish numbers or email addresses).