One of the big stories in the running world a few weeks ago was Mo Farah's collapse at the New York City Half-Marathon. Though it turned out okay—Farah regained consciousness and was carted away in a wheelchair, then appeared later at the post-race press conference—for a moment, everyone present surely feared the worst.
Usually, when runners collapse after a race, they'll be fine. The most common cause of post-race collapse is a transient drop in blood pressure that occurs when your muscles stop contracting rapidly and when your heart rate drops precipitously after you stop running. After lying down for a bit, elevating their legs, drinking some water, and being tended to by medical staff on-site, they'll recover quickly. But occasionally, runners collapse at a race for much more serious reasons. Hyperthermia and hyponatremia usually affect slower runners for a number of reasons (they tend to be heavier, their race takes longer, they have more time to drink too much water, etc.), but are rare in elite runners.1 But being an elite runner offers no protection from another cause of collapse: sudden cardiac arrest.
In 2008, professional runner and Olympic hopeful Ryan Shay collapsed and died only five miles into the Olympic Trials Marathon. The cause was a previously-undetected heart defect, known as hypertrophic cardiomyopathy. Though Ryan Shay's death was one of the most well-known in recent memory, a substantial number of runners die of sudden cardiac failure every year, either while training or while racing. Many of these are middle-aged or older runners succumbing to the same kind of heart disease that claims the lives of thousands of sedentary people every year, but a troubling number are young, seemingly healthy runners aged 35 or younger. These people, like Ryan Shay, have undetected heart abnormalities that leave their hearts prone to failure. Just last week, a 16-year-oldgirl collapsed and died after the Virginia Beach Half Marathon, one of a significant number of high-school and college-aged athletes to suffer sudden cardiac death during the course of their athletic pursuits.
Hard numbers are difficult to come by—given the rarity of sudden cardiac death, numbers in individual studies are all over the board. But the incidence rate appears to be around one death per 100-200,000 young athletes per year.2 While this seems like a vanishingly small number, when you consider that there are about eight million high school and college athletes in the United States at any given time, this lines up with the estimate of about one hundred young athletes dying every year in the United States, extrapolating from a small study of Minnesota high school sport participants.3 Of course, sedentary young people die from sudden cardiac death too, but being an athlete increases your risk by about threefold.
Prevention by testing?
Given the crushingly tragic impact of the death of a young athlete, the obvious question to ask is "can we prevent this"? Currently, almost all high school and college athletes are required to undergo a physical exam by a doctor before being cleared to practice and compete. In accordance with the American College of Preventive Medicine's 2013 position stand, this physical exam involves taking a personal and family history and listening to the athlete's heart with a stethoscope.4 But as was demonstrated in a 1997 study of 5600 high school athletes, these methods are woefully inadequate at detecting heart defects. Many heart defects don't have any family history and can't be detected via a stethoscope.5
Other, more accurate test are available. The two best candidates for large-scale screening of athletes are electrocardiograms or ECGs (also known as EKG, from the Greek) and echocardiograms. ECGs are the classic "wires to the chest" machine you often see on TV medical dramas, while an echocardiogram is an imaging technique based on ultrasound, much like the kind used to image babies before they're born.
If we are to consider the merits of actually doing pre-screening of all young athletes in the US, we need to look at two factors: the reliability of the test in question, and the cost associated with it.
In science, when we talk about how "reliable" a certain test or screening procedure is, we're really talking about two things: the sensitivity and the specificity of the test. A highly sensitive test will have very few "false negatives," meaning in our case, that it won't miss very many kids with heart abnormalities. A highly specific test is one which correctly rules out abnormalities when it comes back negative. The current procedure of family history and stethoscope listening is an example of a test that is fairly specific but not very sensitive. If your doctor hears a heart murmur, it's very likely that there's something wrong with your heart, but plenty of people with heart defects don't have an audible heart murmur.
I'm not nearly qualified enough to do the statistics on how sensitive or specific ECGs and echocardiograms are for young athletes. From the research I've read in the past few days, the consensus seems to be that they are pretty good. But no test is ever perfect. There are bound to be some false positives—young athletes who are determined ineligible for practice or who are referred for more invasive and costly testing procedures, but who don't actually have anything wrong with their hearts. Likewise, even with comprehensive testing, there are bound to be some false negatives: athletes who pass the tests, appearing in good health, yet still suffer sudden cardiac death.
The testing situation is complicated by the fact that the heart of a trained athlete is markedly different than that of a sedentary person. One of the more common heart defects is something called hypertrophic cardiomyopathy, an abnormal thickening of the walls of the heart. This can be detected by an ECG or an echocardiogram, but in some cases, it can be hard to distinguish hypertrophic cardiomyopathy from "athlete's heart"—the normal cluster of responses in the heart to aerobic conditioning. As discussed in a review article by Barry Maron, a doctor at the Minneapolis Heart Institute, there exists a "gray area" where distinguishing the difference between a dangerous heart condition and a benign response to training can be difficult.2 Despite this, there are guidelines for doctors on how to interpret ECGs in athletes and when to request further testing.6
The other issue associated with large-scale testing is cost. It's an uncomfortable issue, because it essentially involves putting a price tag on somebody's life, but it's unavoidable in this case. Even if we were to accept that ECGs and echocardiograms are highly sensitive and highly specific tests for heart defects, there's no way it would be feasible to screen all eight million young athletes in the country if the tests were $1,000,000 each. In contrast, we'd be foolish not to incorporate ECGs or echocardiograms into pre-competition physicals if they were only a few dollars each.
Again, I have neither the qualifications nor the data to run the numbers on the cost-benefit analysis for either of these. As I mentioned earlier, as of 2013, the American College of Preventive Medicine does not support widespread use of ECGs or echocardiograms in screening young athletes. However, the European Society of Cardiology published a consensus statement in 2005 recommending the use of 12-lead ECGs as part of a standard pre-participation screening for all young athletes in Europe. "The addition of 12-lead ECG has the potential to enhance the sensitivity of the screening process for detection of cardiovascular diseases with risk of sudden death," write the authors of the paper, despite the downside of false positive tests.7 The potential for lives saved, they argue, is worth the cost.
Italy's universal screening program
Much of the evidence for the European Society of Cardiology's recommendation is based on the experiences of doctors in Italy, where pre-participation heart screening of all young athletes has been legally mandated since 1982. A 2006 scientific report detailed the results from a 25-year time span. Corrado et al. write that, during the period of the study, about 42,000 athletes were screened in the Veneto region of Italy.8 Pre-participation screening via 12-lead ECG disqualified two percent of potential athletes. At the same time, the rate of sudden cardiac death in athletes dropped from 3.6 deaths per 100,000 people per year to 0.4.
The graph below demonstrates both the risks of participating in sports—before screening was implemented, athletes were three to four times as likely to die from sudden cardiac death as nonathletes—and also the efficacy of the testing program: the rate of sudden cardiac deaths dropped by nearly 90%.
|Using electrocardiograms to screen all young Italian athletes decreased the rate of sudden cardiac death by 89%|
If the Italian experiment could be replicated in the United States, it should have a significant impact on the rate of sudden cardiac death among young athletes. Although it's hard to find good statistics, let's say there are roughly 100 deaths per year in the US (about in line with the data available).3 A program as robust as the one in Italy could prevent 89 of these. It remains to be seen if the American medical infrastructure is up to the task—is it possible to implement a system which could accurately analyze ECGs from hundreds of thousands or possibly millions of young athletes every year? Given the relative ease with which tests for colon cancer and breast cancer were introduced on a nationwide scale, I'd be inclined to say yes (though these tests have also been swirled up in controversy over their sensitivity, specificity, and cost versus benefit).
Risk, liability, and personal choice
The last issue to consider is personal choice. If testing were cheap and accurate, almost everyone would support requiring it. But if an athlete is found to have a heart abnormality, should he or she be allowed to play?
In the 1990s, an Illinois prep basketball star named Nick Knapp collapsed during a pick-up game at his high school. Fortunately, even though his heart had stopped, there were bystanders trained in CPR, and an ambulance arrived quickly. Knapp made a full recovery, albeit with a defibrillator implanted in his stomach, and was determined to play in the NCAA. Northwestern University promised him a scholarship, but when the team doctors found out about his heart condition, they prohibited him from practicing or competing for the Northwestern basketball team. Knapp sued, arguing that it should be his choice whether to risk his life and health to play basketball. He won an initial ruling, but Northwestern prevailed in a ruling by the US Court of Appeals. Northwestern honored his scholarship, but he never practiced or competed for them. Knapp's case highlights some tough issues—what happens when a supremely talented young runner is found to have a heart condition? How would you feel if you discovered you had an abnormality in your heart? It certainly gives me pause, both as a coach and as a runner myself.
Despite no signs of movement on ECG or echocardiogram pre-screening by national organizations like the American Heart Association or the American College of Preventive Medicine, some schools and communities are moving forward. Dr. Darshak Sanghavi, a pediatric cardiologist at the Brookings Institution, described in a 2009 column in Slate magazine how big-time college programs like Purdue and Ohio State screen all of their incoming athletes with ECGs or echocardiograms, and some private high schools are doing the same.
Is it time for universal ECGs or echocardiograms as part of pre-participation screening for all young athletes? I'm not a certified actuary who can crunch the numbers on the costs and benefits of doing ECGs on eight million athletes in the United States, nor am I a medical doctor who can contemplate the relative risk of allowing an athlete with a heart defect to train and compete in high school or college athletics, nor am I a sports administrator who could gauge how easily comprehensive pre-screening could be implemented on a cost-effective basis. I'm just a coach and a scholar who's seen some very promising data on how we could reduce the incidence of sudden cardiac death in athletes. At the very least, it's time to seriously and rigorously re-evaluate the efficacy of universal ECG pre-screening in light of the long-standing success of Italy's universal athletic pre-screening program. School and community-based efforts to have automated external defibrillators available to save lives have been very successful at resuscitating athletes who collapse because of sudden cardiac arrest,9 so perhaps we can have similar community and nonprofit-based initiatives to make sure those AEDs are needed as rarely as possible.
1. Asplund, C. A.; O'Connor, F. G.; Noakes, T. D., Exercise-associated collapse: an evidence-based review and primer for clinicians. British Journal of Sports Medicine 2011, 45 (14), 1157-1162.
2. Maron, B. J., Sudden Death in Young Athletes. New England Journal of Medicine 2003, 349, 1064-1075.
3. Maron, B. J.; Gohman, T. E.; Aeppli, D., Prevalence of sudden cardiac death during competitive sports activities in Minnesota High School athletes. Journal of the American College of Cardiology 1998, 32 (7), 1881-1884.
4. Mahmood, S.; Lim, L.; Akram, Y.; Alford-Morales, S.; Sherin, K., Screening for Sudden Cardiac Death Before Participation in High School and Collegiate Sports. American College of Preventive Medicine Position Statement on Preventive Practice. American Journal of Preventive Medicine 2013, 45 (1), 130-133.
5. Fuller, C. M.; McNulty, C. M.; Spring, D. A.; Arger, K. M.; Bruce, S. S.; Chryssos, B. E.; Drummer, E. M.; Kelley, F. P.; Newmark, M. J.; Whipple, G. H., Prospective screening of 5,615 high school athletes for risk of sudden cardiac death. Medicine & Science in Sports & Exercise 1997, 29 (9), 1131-1138.
6. Corrado, D.; Pelliccia, A.; Heidbuchel, H.; Sharma, S.; Link, M.; Basso, C.; Biffi, A.; Buja, G.; Delise, P.; Gussac, I.; Anastasakis, A.; Borjesson, M.; Bjørnstad, H. H.; Carrè, F.; Deligiannis, A.; Dugmore, D.; Fagard, R.; Hoogsteen, J.; Mellwig, K. P.; Panhuyzen-Goedkoop, N.; Solberg, E.; Vanhees, L.; Drezner, J.; Estes III, N. A. M.; Iliceto, S.; Maron, B. J.; Peidro, R.; Schwartz, P. J.; Stein, R.; Theiene, G.; Zeppilli, P.; McKenna, W. J., Recommendations for intepretation of 12-lead electrocardiogram in the athlete. European Heart Journal 2010, 31 (2), 243-259.
7. Corrado, D.; Pelliccia, A.; Bjørnstad, H. H.; Vanhees, L.; Biffi, A.; Borjesson, M.; Panhuyzen-Goedkoop, N.; Deligiannis, A.; Solberg, E.; Dugmore, D.; Mellwig, K. P.; Assanelli, D.; Delise, P.; van-Burren, F.; Anastasakis, A.; Heidbuchel, H.; Hoffmann, E.; Fagard, R.; Priori, S. G.; Basso, C.; Arbustini, E.; Blomstrom-Lundqvist, C.; McKenna, W. J.; Theine, G., Cardiovascular pre-participation screening of young competitive athletes for prevention of sudden death: proposal for a common European protocol. European Heart Journal 2005, 26 (516-524).
8. Corrado, D.; Basso, C.; Pavei, A.; Michieli, P.; Schiavon, M.; Thieman, T. J., Trends in Sudden Cardiovascular Death in Young Competitive Athletes After Implementation of a Preparticipation Screening Program. Journal of the American Medical Association 2006, 296 (13), 1593-1601.
9. Drezner, J. A.; Toresdahl, B. G.; Rao, A. L.; Huszti, E.; Harmon, K. G., Outcomes from sudden cardiac arrest in US high schools: a 2-year prospective study from the National Registry for AED Use in Sports. British Journal of Hospital Medicine 2013, 47 (18), 1179-1183.