FRIDAY, Aug. 12 (HealthDay News) -- About 76 young U.S. athletes collapse and die from sudden cardiac arrest during practice or a game every year, which has led some experts to call for mandatory electrocardiograms to screen players for possibly fatal heart defects.

But a recent study found that pediatric heart specialists don't always get it right when reading these tests, known as ECGs.

"What this does is add another layer of complication and confusion to the controversy," said first study author Dr. Allison Hill, a pediatric resident at Stanford University when she did the research. "Not only do ECGS not always show diseases that could lead to sudden cardiac death, but the people reading them are not always interpreting them correctly."

During an ECG, electrodes attached to the chest and limbs measure electrical impulses generated as the heart beats. ECGs can detect heart rhythm abnormalities and other conditions that could cause the heart to stop suddenly.

The most common cause of sudden cardiac death in young people is hypertrophic cardiomyopathy, a thickening of the heart muscle that makes it more difficult to pump blood, Hill said. Other causes include myocarditis, an inflammation of the heart, and Wolff-Parkinson-White syndrome, which can lead to excessively rapid heart rate.

This study found that pediatric cardiologists missed dangerous heart abnormalities about 32 percent of the time and mistakenly diagnosed a heart abnormality in 30 percent of cases. High rates of inappropriate sports guidance could result from the errors, the researchers said.

For the study, recently published online in the Journal of Pediatrics, researchers asked 53 pediatric cardiologists to interpret 18 ECGs from teens with and without heart abnormalities. On average, doctors correctly interpreted 12.4 ECGs.

The doctors were also asked to determine if it was safe for the child to continue in sports. Some heart defects are more severe than others, and having a heart abnormality doesn't necessarily mean a child can't participate in athletics.

For about three-quarters of the teens without heart problems, doctors made the correct recommendation in giving them the all-clear to participate in sports.

Among those with heart defects, doctors were correct 81 percent of the time in restricting sports, but in 19 percent of cases, they would have approved participation even though it would have been dangerous to do so, Hill said.

"An ideal screening test is going to have 100 percent accuracy," said Hill, now a pediatric cardiologist at Children's Hospital Boston. "In this case, even when ECGs showed underlying cardiac disease, pediatric cardiologists were not always able to pick up on it."

Physicians were better at spotting some heart defects than others. Part of the difficulty in reading ECGs is that certain dangerous heart abnormalities mimic healthy changes in the hearts of athletes, Hill noted. A fit heart, for example, tends to grow larger and beat more slowly, but some abnormalities can cause a similar change.

The American Heart Association does not recommend mandatory ECG screening for U.S. youth athletes for several reasons, one being cost -- about $431 based on the Medicare reimbursement rate, according to background information in the study.

Instead, the AHA urges competitive athletes to undergo a medical history and physical exam every two years. ECGs are warranted in kids with a history of fainting, chest pain, trouble breathing, blood pressure issues or a family history of early heart disease or premature death, said Dr. Monica Kleinman, chair of the American Heart Association's Emergency Cardiovascular Care Committee and clinical director of the medical/surgical intensive care unit at Children's Hospital Boston.

Kleinman said that instead of mandatory ECG testing, providing automated external defibrillators (AEDs) at every school and youth sporting event -- and making sure that people know where they are and how to use them -- may go a longer way in preventing sudden cardiac death. AEDs are used in conjunction with CPR chest compressions to restart the heart.

"Having an AED at an athletic event is a very effective way of providing a safety net for those athletes at risk who never know it, and for those bystanders and coaches walking around with heart disease who may have sudden cardiac arrest," Kleinman said.

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