Pediatric cardiologists not always accurate in interpreting ECG results for young athletes

Pediatric cardiologists are prone to misinterpreting electrocardiograms when using the results to determine whether young athletes have heart defects that could make exercising perilous, according to a new study from the Stanford University School of Medicine and Lucile Packard Children's Hospital. This is the first research to examine the acumen of pediatric cardiologists from several health-care institutions in using ECGs to detect rare heart conditions associated with sudden cardiac death.

Public outcries about sudden cardiac deaths among athletes have already prompted some European countries to require that young athletes undergo heart exams via ECG before they participate in sports. Even though the number of sudden cardiac deaths among young U.S. athletes is low — an estimated 76 per year —some people have suggested that athletes here should also receive mandatory ECGs so that those vulnerable to sudden cardiac death could be warned not to play sports.

Not so fast, say the authors of the new research.

"An ECG doesn't always pick up the abnormalities that may predispose someone to sudden cardiac death," said Allison Hill, MD, the study's first author. "And this exam can be difficult to interpret, even if the person reading the scan is a pediatric cardiologist." Hill recently finished her pediatric residency at Packard Children's Hospital and is now a pediatric cardiology fellow at Children's Hospital Boston.

An ECG exam uses electrodes attached to the chest and limbs to measure the electrical impulses generated as the heart beats. ECGs can detect heart rhythm abnormalities and other symptom-free heart conditions that could lead to sudden cardiac death.

In the new study, which will be published online July 14 in the Journal of Pediatrics, 53 members of the Western Society of Pediatric Cardiology were asked to interpret a set of 18 ECG exams, some from healthy athletes and some from those with heart defects. The physicians, who had an average of five to 15 years of experience in their field, accurately diagnosed the heart conditions only 67 percent of the time. They correctly permitted sport participation for healthy individuals 74 percent of the time, and correctly restricted sport participation for those with cardiac defects 81 percent of the time.

"As athletes' hearts grow stronger, they undergo some changes that make it very difficult to tell: Is this a well-trained athlete or does this person have some underlying disorder that may predispose them to sudden cardiac death?" Hill said. A fit heart tends to grow somewhat larger and beat more slowly, which can make it look similar on an ECG to a defective heart vulnerable to sudden cardiac death. This similarity could lead to unnecessary exclusion of healthy young people from sport participation.

Conversely, some young athletes who are predisposed to sudden cardiac death may be given a clean bill of health based on a flawed ECG interpretation.