Determining the Best Way to Prevent Sudden Death in Athletes

It's been a bad autumn for deaths during U.S. running races—at least six during half marathons and one during a marathon. Although the specific causes of death aren't known in all cases, heart ailments are at the top of the list of possible explanations whenever someone dies suddenly during an athletic event, be it a road race, triathlon, or a football or basketball game. As rare as these events are when compared with deaths from car accidents, homicide, or even the flu, doctors are debating whether lives could be saved by more carefully scrutinizing athletes before they compete. Sounds good, but is it possible?

First, let's understand what problems doctors are trying to ferret out, and in whom. When a middle-aged person experiences sudden cardiac death or a fatal heart attack during athletic exertion, he is more likely to have plain old heart disease (also called coronary artery disease) caused by a buildup of plaque inside the blood vessels leading to the heart, says Euan Ashley, an assistant professor of cardiology at the Stanford School of Medicine and director of the Stanford Hypertrophic Cardiomyopathy Center. But when a high school, college or younger elite athlete collapses and dies, he or she most likely had an undiagnosed inherited cardiovascular disease, most commonly hypertrophic cardiomyopathy, in which the heart muscle thickens and can throw off the rhythm of the heart. (Other electrical malfunctions in the heart are also a possibility.)

Why are these problems an issue during sporting events or strenuous exertion? While exercise can dramatically cut the chance of heart disease, during the minutes you actually are exercising, your risk of a heart attack or sudden death actually temporarily rises, says Ashley. The long-term benefits of exercise vastly outweigh any short-term risk, so there's no excuse for not exercising unless your doctor specifically orders it. (Even 2007 research on the body-stressing marathon suggests that it's riskier to drive the course than to run it.)

The debate over whether to more rigorously screen for hidden heart problemslargely centers on younger athletes. High schools and colleges typically require a medical and family history and a physical exam. But those measures alone will identify only about 20 percent of people with underlying problems that might lead to cardiac arrest, says Jonathan Drezner, a primary-care sports medicine doctor in the University of Washington's Department of Family Medicine author of a recent article on the topic in the British Journal of Sports Medicine. Adding a 12-lead electrocardiogram, or ECG—which tracks the electrical activity in the heart—could bring that figure up to 70 or 75 percent, he says. Many pro athletes in this country are already required to have ECG screening. And Italy, which in 1982 launched a nationwide ECG screening program for all its young athletes, saw the rate of sudden death drop by 89 percent, according to a review published in the current issue of Sports Health.

Despite ECG's advantages, there are many reasons to proceed cautiously. First, it's not at all clear that Italy's experience can be directly extrapolated to this country. And no one knows just how many deaths ECG could prevent since the incidence of sudden cardiac death isn't actually known; estimates range from 1 in 50,000 to 1 in 200,000.

There's also the very real downside of the test detecting abnormalities—like an enlargement of the heart muscle called athlete's heart—that are benign and require no medical treatment. In fact, as many as 40 percent of elite athletes, especially African-Americans, may have ECG abnormalities caused by their rigorous training, according to the Sports Health review. Investigating those abnormalities may require follow-up tests like an echocardiogram, stress test, or MRI. But the real problem is that sometimes athletes need to stop training to see whether the heart will shrink back to normal size, as it should if it were simply growing in response to exercise. That detraining period may be as long as three or six months, says Sharlene Day, an author of the recent Sports Health review and a cardiologist at the University of Michigan, where she directs the hypertrophic cardiomyopathy clinic. That's a long time for athletes to be out of the game; high school and college athletes may miss out on scholarships, and pro athletes can lose actual income. (Some researchers say knowledge of training-related changes to the heart has increased to the point where the false-positive rate can be significantly lowered.)

Because of these and other issues, the American Heart Association does not recommend mandatory ECGs for all young athletes before they can compete. The organization says more data—through more complete reporting—is needed to figure out the true prevalence of sudden cardiac death. Other issues to be addressed, says Drezner, include training physicians to do the screening and having enough facilities and resources to support it. At Stanford, researchers have instituted a voluntary ECG screening program for the university's athletes to study whether it can be done effectively and at a reasonable cost.

What about screening those older recreational athletes, who are at greater risk of dying suddenly from cardiac arrest than younger athletes? That would be tough, says Ashley, because an ECG isn't likely to predict heart attacks in people with no symptoms of heart disease (such as chest pain or shortness of breath). Right now, studies suggest that for people without symptoms, ECG is useful as a screening tool only in men with diabetes or men who are over 45 and have at least two cardiovascular disease risk factors (like hypertension and high cholesterol) to see if it's safe to initiate a vigorous exercise program. (It also may be helpful for people under 45 with a particularly strong risk of heart disease or in elderly patients with one or fewer risk factors.)

So what should you do if you want to know whether it's safe to start running or doing other forms of vigorous exercise? First, get screened for heart risk factors such as high blood pressure and cholesterol, says Day. You should also know your family history and tell your doctor if close relatives died of heart disease at an early age—before age 50 for men and 55 for women. Once you begin an exercise routine, pay attention to your body so you can be alert to any symptoms that arise. Warning signs include chest pain and pressure. And though it's rare, losing steam or "oomph" in your workouts, especially if the heart rate is high, may signal a problem. Women need to be aware of "female" heart disease symptoms, since these may differ from men's.

You may also want to ask if you gym keeps an automated external defibrillator. Drezner was the author of a study published earlier this year that found a 64 percent survival rate among people suffering sudden cardiac arrest on high school campuses with at least one onsite AED. That compares to the usual survival rate of just 5 to 10 percent, he says. This year, the New York City Marathon had AEDs at every medical station after the first few miles of the race.

Drezner feels the best way to prevent sudden cardiac death is a combination of primary prevention, screening, and AEDs. But even if ECGs are included in screening, there will never be a 100 percent assurance that problems will be caught early. "There's some risk to life," he says. And these problems—scary as they seem—are extremely rare. So take appropriate precautions, lace up those shoes, get out there, and enjoy being active.