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To identify young athletes at risk for sudden cardiac arrest, it’s better to use a questionnaire and electrocardiogram (EKG) than the questionnaire and physical exam recommended by the American Heart Association (AHA).
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It is extremely rare for a young athlete to drop dead of sudden cardiac arrest: The risk is 1 in 80,000 among US high school athletes and 1 in 50,000 among US college athletes each year. That translates into about 75 such deaths annually among those under 25. But the tragic loss of a young life, combined with the shock that there were (usually) no warning signs, has spurred medical and sports groups to seek the best way to identify those at risk.
Virtually everyone agrees that screening should start by asking about family and personal medical history, such as having close relatives who died of heart disease before age 50, chest pain during physical exertion, or high blood pressure. The AHA recommends 10 such questions. But there the agreement ends.
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The AHA also recommends a physical exam, including listening to the heart, for the young athletes (regardless of what the questionnaire reveals). Although it recognizes that an EKG is the most sensitive way to identify hearts at risk of suddenly stopping, the organization explicitly rejects EKGs as impractical, expensive, and likely to yield too many false positives — meaning people are flagged as being at risk of sudden cardiac arrest but actually are not. The European Society of Cardiology does recommend using an EKG to screen athletes.
A new study in the Canadian Journal of Cardiology suggests a third way: asking questions about personal medical history that do a better job than the AHA questionnaire of identifying those at risk for sudden cardiac death and of clearing those who are not at risk (resulting in fewer false positives), administering an EKG, and (for those at high risk) having a cardiologist interpret it. It skips the physical exam.
Cardiologists at the University of British Columbia compared this approach to the heart association’s, with about half of 1,419 athletes aged 12 to 35 getting the AHA-recommended questionnaire plus physical exam and half answering a questionnaire the researchers designed to better differentiate between symptoms of serious cardiac disease and symptoms of less dangerous conditions. For instance, it included questions meant to distinguish between dizziness, fainting spells, or chest pain caused by serious heart conditions rather than other, more common causes, such as exertion. “It’s designed to be more specific in identifying symptoms that are concerning,” said UBC’s Dr. James McKinney, who led the study.
As expected, the incidence of significant cardiac disease was low: 0.52 percent in both groups. In those getting the heart association screening, though, every problem flagged by physical exam turned out to be a false alarm, and only 4 percent of those flagged by the questionnaire were really at risk, as determined by EKG. The more precise questionnaire plus EKG had half as many false positives.
This method was also better at flagging those at risk of sudden cardiac arrest. Of the seven athletes it found to have a serious heart condition, six were identified by EKG; the heart association questionnaire plus exam would have detected only two of those. “The questionnaire reduces the rate of false positives, and the EKG is more sensitive than both history and physical exams” in detecting potentially fatal abnormalities, McKinney said.
Experts on sudden cardiac arrest said the Canadian findings need to be validated in a larger study. But they were not surprised that the heart association questionnaire plus physical exam were so bad at identifying people at risk of sudden cardiac arrest. “More than 80 percent of young athletes [whose hearts stop] have no symptoms” before that, said Dr. Michael Papadakis of St. George’s University in London, who was not involved in the study. Asking about symptoms therefore misses the vast majority of those at risk, and identifying rare defects by listening to the heart is very difficult, he said, so the combination “will fail to detect the majority of athletes who are at risk of sudden cardiac death.”
A 2015 analysis of 15 screening studies of 47,137 athletes also found that EKG was the best screening method. Its chance of detecting a problem was five times higher than with a family or medical history, and 10 times higher than with a physical exam, and it produced a lower false positive rate. Last month, the American Medical Society for Sports Medicine concluded that history plus physical often fails to identify athletes at risk of sudden cardiac arrest and that EKG can do better.
“When you look at all the scientific evidence, including this Canadian study, it’s really clear that you increase the detection of those at risk of cardiac arrest if you do EKG,” said Dr. Jonathan Drezner, director of the Center for Sports Cardiology at the University of Washington and team physician for the Seattle Seahawks. “It’s also clear that we now have a process [questionnaire plus physical exam] that’s ineffective.”
A spokesperson for the AHA said it was unable to provide an expert to speak about its recommendations.
More and more evidence suggests that very specific questions about medical history plus EKG, but no physical, will correctly identify more athletes at risk of cardiac arrest, and have fewer false positives, than a questionnaire plus physical.