THURSDAY, Sept. 9 (HealthDay News) -- Most teenagers think they're invincible, and that goes double for talented teenage athletes. They're young, immortal, at the top of their game, the envy of their friends.

So when news hits that an apparently healthy, high school or college athlete has dropped dead in the midst of playing his or her favorite sport, millions of parents get understandably anxious.

The uppermost question becomes: Should my child be screened before participating in sports? What tests are needed? And how can we be sure that he or she is truly healthy enough to compete?

Everyone agrees that a medical checkup before participating in sports is crucial. But the agreement seems to stop there. At the core of the conflict over further testing is how extensively young athletes' hearts should be tested before they're cleared for athletic participation.

"I think everyone should have a doctor who evaluates them, and the doctor should know the child is going to be participating in athletics," said Dr. Paul Thompson, the director of preventive cardiology at Hartford Hospital in Connecticut, who helped write a joint position statement in 2007 from the American College of Sports Medicine and the American Heart Association.

That statement recommends cardiovascular screening for high school and college athletes before they start participating in athletics and at two- to four-year intervals. The screening should include a family history, a personal history and an exam "focused on detecting conditions associated with exercise-related events," according to the groups' recommendation.

But, there's more: "The AHA does not recommend routine, additional noninvasive testing such as a routine EKG [electrocardiogram, which assesses the heart's electrical rhythms]."

The American Academy of Pediatrics seems to agree. "Every athlete should have a thorough history [taken] from the athlete as well as the athlete's family," explained Dr. Reginald Washington, a pediatric cardiologist and chief medical officer at Rocky Mountain Hospital for Children in Denver and past chairman of the academy's committee on sports medicine and fitness.

The doctor should ask about any chest pain and dizziness, and whether the athlete has ever passed out or experienced a racing or unusual heartbeat, Washington said. The physician should also ask if the athlete's parents have had early heart disease, before age 55 for a man and 65 for a woman. And the physical exam, he said, should be thorough and include listening to the heart, taking blood pressure and feeling the pulse.

"If all of that is normal and the family history is normal, no further tests need to be done," said Washington, echoing the academy's stand.

But others disagree strongly, calling for universal and extensive testing of all young athletes to avert future tragedy.

Heart experts from Johns Hopkins Medicine in Baltimore contend that both an EKG and an echocardiogram -- which is an ultrasound that measures heart size, pumping function and checks for faulty heart valves -- are crucial to detect early signs of heart defects in young athletes because neither test alone will catch all potential problems.

In testing 134 high school athletes competing in the Maryland state track and field championships in 2008, for instance, no life-threatening heart defects were found but blood pressure abnormalities that required further testing and monitoring were detected in 36 athletes, some by EKG and some by echocardiogram, the Hopkins doctors reported at an American Heart Association session in late 2009.

Testing in 2009, according to a Hopkins report, found a serious heart valve disease in one track-and-field athlete and another with an undiagnosed heart condition that could require a transplant in the future. Neither athlete had reported any symptoms.

"If you are going to screen, it has to be comprehensive," Dr. Theodore Abraham, an associate professor at Hopkins' School of Medicine and its Heart and Vascular Institute, said in a prepared statement.

Other studies have found pros and cons to extra screening.

For instance, Harvard researchers who looked at 510 college athletes found that screening with a history and physical exam alone has an overall sensitivity of 45.5 percent, meaning it would find existing problems in about 45 of every 100 athletes screened. But adding an EKG to the screening boosted it to more than 90 percent.

However, the EKGs were also linked with a false-positive rate -- suggesting a problem when none existed -- of nearly 17 percent, according to their report, published March 2 in the Annals of Internal Medicine.

A separate study in that issue, on the cost-effectiveness of such screenings, reported that adding EKGs to screenings of young athletes saves two years of life per every 1,000 athletes, at a per-athlete cost of $89.

Screening policies differ from region to region across the country. In Houston, for instance, athletic trainers at 10 high schools are using laptop systems to give young athletes EKGs, and a doctor in the city has launched a program to provide heart screening to all sixth-graders, eventually hoping to screen all sixth-graders in Texas.

But there are downsides to such universal screening, others say.

"About 10 percent of kids who get EKGs are thought to have something the matter with them by the EKG," Thompson, the Connecticut doctor, said. "That drives additional testing, and nearly all don't have anything wrong."

The problem, he said, is not just wasted health-care dollars but the anxiety caused by additional testing, for athletes and their parents.

Thompson said he is not oblivious to parental worry or to the sad reality that some athletes die unexpectedly each year.

"Every single one of these deaths is an incredible tragedy," he said, adding that he will do extra testing if parents are very worried. "But when people have looked at this, the death rate in the U.S. is about one in every 250,000 athletes. There is not really conclusive research to show [extensive testing] saves lives."

Also, in mass screenings -- where kids line up and are screened quickly -- accuracy may suffer, said Washington, the Denver pediatric cardiologist. "A good, thorough ultrasound should take a half-hour," he said. "If you line up all the kids [at a school or on a team] to have a portable ultrasound, you will miss some of these subtle abnormalities."

But Sharon Bates, a parent who founded the Anthony Bates Foundation after her athlete son, Anthony, died unexpectedly in 2000 and was found to have had an enlarged heart, disagrees with the arguments against mass screenings.

Even if a problem picked up is minor, she said, you have a right to know, and it needs to be addressed.

Bates's son had passed the typical pre-athletic physical with flying colors, she said, yet he still had a major cardiac problem.

Her Phoenix-based foundation promotes universal screenings for all youth, not just athletes, she said.

As Abraham said, "What is the price for a single life?"

More information

The Nemours Foundation has information for kids on sports physicals.