Test May Help Spot Killer of Young Athletes

A young athlete, apparently fit and healthy, dies suddenly.

Only later do doctors discover his hidden flaw, a condition called familial hypertrophic cardiomyopathy. His heart muscle had grown unnaturally thick, making it hard to beat normally. And, during exercise, it stopped.

But who could have known?

Now, researchers say, they have a way to tell--sometimes.

Genetic testing of a blood sample can find some forms of mutation that seem to weaken the protein of the heart muscle, said Dr. Ali J. Marian, an instructor in medicine-cardiology at Baylor College of Medicine in Houston.

Major research facilities, such as hospitals affiliated with medical schools, could do the lab work, if not now, then within about a year, Marian said.

“This type of test is practically 100% accurate,” Marian said. “The final confirmation is looking at the sequence of DNA (the genetic material).”

In some cases, it can distinguish between people at high risk of early death and those who have the condition but face relatively less risk, and the discovery of other mutations may make this more accurate, Marian said.

The test may open more exceptions to the general prohibition on strenuous exercise for people with hypertrophic cardiomyopathy, he said. Without the test, doctors must assume the worst.

The disease is inherited in two-thirds of cases, so if the genetic flaw is found in one member, all should then be tested, Marian said.

Approximately 20,000 people die each year from the disease, said Marian, who presented his findings at a recent American Heart Assn. conference. The AHA calls the condition “the most common cause of sudden cardiac death in the young, particularly in athletes.”

The value of genetic testing is limited, however, said Dr. Barry J. Maron, a senior investigator at the National Heart Lung and Blood Institute.

Genetic testing currently is expensive and time-consuming.

And the discovery of 10 mutations in 16 families indicates far more have yet to be found, said Maron, a leading expert on hypertrophic cardiomyopathy.

“It’s valuable for people in the families who want to know if they are carrying the gene,” Maron said. “I think it’s premature to talk about applications to populations.”

Finding these athletes, however, may not be easy, even with a genetic test.

Heart disease in general is relatively rare in the young, and the incidence of this form is probably not more than 100 a year among young athletes, said Dr. Philip A. Ades, an associate professor of medicine and director of cardiac rehabilitation at the University of Vermont College of Medicine in Burlington.

Winnowing through the estimated 25 million competitive young athletes in order to find them would run up a huge medical expense, he said.

Once the genetic marker is found, a doctor would still have to examine the patient to see if the disease is present--and, if it is, how far advanced, he said.

“This is definite progress, but it may or may not be related to the issue of screening of athletes,” Ades said.

Ades presented overall cardiac screening proposals to the AHA and reported them in a medical magazine, the Physician and Sportsmedicine.

A questionnaire with the article asks, among other things, whether the patient has been told he has a heart murmur, whether he experienced chest pains or fainting within the last two years, or whether anyone in the family has been diagnosed with an abnormally thickened heart.