FRIDAY, June 23, 2006 (HealthDay News) -- Experts say differences in the heart's structure may explain the finding that most young athletes who suffer cardiac arrest die -- even after excellent attempts at resuscitation have been made.
Researchers reported earlier this week that measures that have proven tried and true for older people, such as cardiopulmonary resuscitation (CPR) may not always work with younger athletes.
The study, reported in the July issue of Heart Rhythm, found that eight of nine college athletes who suffered sudden cardiac arrest did not survive, despite optimal efforts to save them.
The reason, according to researchers at the University of Washington, Seattle, may be that cardiac arrest in younger people is typically caused by abnormalities linked to structural heart disease. In contrast, older people who suffer cardiac arrest typically have normally structured hearts.
"One of our hypotheses to explain why success rates are lower than expected is that resuscitating athletes with structural heart disease may be more difficult than resuscitating a structurally normal heart," explained lead researcher Dr. Jonathan A. Drezner, an assistant professor of family medicine.
For older victims of sudden cardiac arrest, the underlying cause is typically hardening of the arteries (atherosclerosis) and coronary artery disease.
"In young athletes, the main cause is usually a structural abnormality, with the most common cause of sudden cardiac death in young athletes hypertrophic cardiomyopathy, an enlarged and abnormal heart muscle," said Drezner, who is also associate director of the Sports Medicine Fellowship at the university.
The researchers evaluated nine cases of sudden cardiac arrest occurring in nine college athletes between 1999 and 2005. All but one died.
All the athletes suffered a "witnessed collapse," meaning bystanders were there and able to respond. In all case, the victims received CPR and/or use of an automated external defibrillator (AED), a device to restore heart rhythm to normal. These procedures were carried out either by emergency medical responders or athletic trainers. In seven cases, a shock was administered with the AED -- on average just 3.1 minutes after the cardiac arrest.
But only one of the players survived.
Four played basketball, two football, two lacrosse and one was a swimmer. All were male. The survivor played basketball.
"It's still surprising, given the young age," said Drezner of the fact that all but one died.
On further evaluation, the underlying cause of the sudden cardiac death was found to be hypertrophic cardiomyopathy (enlarged heart) in five students and heart attack in one. Two died from "commotio cordis" -- cardiac arrest caused by a blow or trauma occurring just as the heart is preparing to pump. This sudden trauma disrupts the heart's vital electrical system.
The use of AEDs outside of the hospital has helped save lives in recent years, experts say. The devices, found in casinos, airports, on airlines and in public buildings, have resulted in survival rates of 36 percent to 52 percent among the general population, Drezner noted.
Another expert, Dr. Mark Link, an associate professor of medicine at Tufts-New England Medical Center, Boston, agreed with Drezner. "You would have expected more of [the athletes] to survive. You would expect a 40 to 50 percent survival rate if an AED is applied within three minutes. And that is well-documented by other studies."
Link, who is also director of the Center for the Evaluation of Athletes at Tufts, called the results of the Seattle study "depressing and concerning." In his own research, published earlier this year in the journal Pediatrics, Link found that chest protectors worn by children while playing baseball or lacrosse didn't protect them from sudden death if they were hit in the chest with a ball and suffered commotio cordis.
While the findings are worrisome, Drezner and Link urged parents and athletes to put the findings in perspective and said officials should consider the study a reminder to focus on emergency plans. "It's an unusual event that a young athlete dies suddenly," Link said. About 75 to 150 young athletes per year experience sudden cardiac arrest in the United States, Drezner estimated, citing several studies.
"The emphasis is certainly not to be critical of the responders," Drezner said, noting that they all did a great job. "It could be that, in young athletes, the window [to save them] is short."
To reduce risk, young athletes should undergo a comprehensive history and physical before participating in sports, Drezner said. It should be done by a physician who is familiar with screening for athletic physicals. Any child or young adult with symptoms of heart problems, such as fainting while exercising or experiencing chest pain, should have a comprehensive cardiac exam, he said.
However, he acknowledged that, just as happens in the old, cardiac arrest can occur in the young with no warning. With that in mind, Drezner said, schools should review their plans for emergency protocols and be sure good procedures are in place.
To learn more about high school emergency protocols, visit the National Athletic Trainers' Association.