Physicians now have quantitative help in distinguishing between the physiologic effects of athletic training on the adolescent heart and the potentially lethal condition of hypertrophic cardiomyopathy, according to an article in the October 16th issue of the Journal of the American College of Cardiology.

"It's the first study of its kind that's ever identified physiologic upper limits for left ventricular wall thickness in adolescent athletes," said lead author Sanjay Sharma, M.D.

Because all of the previous studies had examined adult athletes, physicians had to guess about how to apply the data to smaller, less mature teenage athletes. Sharma said that the results of the current study have immediate clinical relevance and can be put to practical use in screening or examining young athletes for hypertrophic cardiomyopathy and in avoiding improper disqualification of athletes who have large but healthy hearts.

The British team performed ultrasound examinations of 720 elite athletes ages 14 to 18 years to determine left ventricular wall thickness and cavity size.

"Our conclusion was that in athletes a wall thickness of 12 mm or more is very unusual. If you do see a wall thickness of 12 mm or more in this age group, always ensure that the cavity size is enlarged. If the cavity size is small in an adolescent with a wall thickness of 12 mm or more, then you should be seriously considering the diagnosis of hypertrophic cardiomyopathy," asserted Dr. Sharma.

Kenneth L. Baughman, M.D., who was not involved in the study, agreed that the results have practical application. "These data should help physicians identify athletes at increased risk of sudden death during athletic competition," Dr. Baughman said.

Competitive athletic training can stimulate growth of normal, healthy hearts. The pathologic condition of hypertrophic cardiomyopathy occurs in only about 1 of 500 young athletes. However, the disorder accounts for about one third of exercise-related sudden cardiac deaths in trained athletes younger than 35 years old, and most of these deaths occur in teenagers.

The researchers recruited elite teenage athletes competing at the regional or national level in sports including tennis, soccer, swimming, boxing, rowing, rugby, cycling, triathlon, field hockey, and karate. There were three times as many boys as girls in the study group, and 98 percent were white. Researchers included 250 control subjects, teens who were not involved in competitive athletics.

The inclusion of very few athletes who were not Caucasian is a major limitation of the study, according to the authors. "I would suggest that at this point we don't extrapolate these findings for all races, but use them only for Caucasians, or exercise great caution before we extrapolate them to other racial groups," Sharma said.

The group is currently gathering data on athletes of African background.