Take-home Messages:

• Prevention of sudden death among athletes is indisputably a desirable goal.
• Pre-participation ECG screening is an area of intense debate, which usually means not enough data.

When it comes to screening, there are several exciting topics to choose from if you’re looking to start a fight: mammography in women below age 40, regular assessment of prostate specific antigen (PSA) in men, and electrocardiography (ECG) screening of young athletes.

Sudden cardiac death (SCD) in young athletes is a tragic event and a vexing problem. Because most cases are the result of ventricular arrhythmias caused by underlying heart disease, an increasing number of countries now enforce medical pre-participation screening that includes recording of a baseline ECG, with the aim of detecting specific cardiac pathologic features associated with sudden death in athletes. However, evidence indicating such a strategy actually prevents sudden death among athletes is largely limited to a single, retrospective Italian study.

One challenge is the large number of problems associated with exercise-related sudden death in young athletes. If you want to create a simple pie chart of all of the CV issues found in an analysis of sudden death in 1,435 competitive athletes, you run out of primary colors long before you finish documenting the CV-related causes of death – there were 19 in all.2

Among young individuals, variously defined as <30 or <40 years of age, the most frequent pathological findings are hereditary or congenital CV abnormalities. In contrast to young subjects, CAD is the most frequent pathological finding among older individuals who die during exertion.

The reported absolute risk of an exercise-related CV event varies but appears to be extremely low in ostensibly healthy subjects. Because of the rarity of exercise-related CV events, studies examining its incidence are limited by small sample sizes and large confidence intervals. In addition, small changes in the number of events can produce large changes in the calculated incidence. Given these caveats, Paul Thompson, MD, said the range in the literature is between 0.8 to 6.2 per 100,000, with a commonly cited estimate of 1 in 100,000.

Screen Gems

In their classic text, Wilson and Jungner outlined the key principles required to support the validity of a screening program.3 Their criteria: The targeted condition should be an important public health issue with a sufficiently long latent or early symptomatic stage; the screening test should adequately recognize the targeted condition in the appropriate population; the test should be acceptable, safe, and inexpensive; and treatment for the recognized disease should be available, affordable, acceptable, and effective. In terms of ECG screening of athletes, the farther down that list you go, the greater the challenge meeting the criteria.

More recently, these principles have been modified by the US Preventive Services Task Force and translated into an analytic framework for screening.4 To be considered effective, a screening program must improve specific health outcomes, such as mortality, quality of life, pain, or function.

In a recent report from a National Heart, Lung, and Blood Institute working group, co-chaired by Dr. Thompson, no direct evidence could be found in a US population that an ECG or any other CV screening program will reduce the incidence of SCD in any of the patient populations thought to be at increased risk.5 Specifically, there has never been a clinical trial in which CV screening has been compared with no screening/usual care with an endpoint of SCD. Furthermore, they could find only limited objective data supporting the other links along the chain of logic. Among the evidence that’s lacking:

• No descriptive epidemiology and etiology of SCD in the young;
• No screening methodology for the target population;
• No optimal management of asymptomatic heart disease that will be discovered by screening programs;
• No data revealing the impact of an ECG screening program on the individual, the family, the community, and society.

With mandatory screening now in place in several parts of the world, what have we learned? Do they work? Recently, Steinvil and colleagues studied the effectiveness of a mandatory pre-participation screening program of athletes.6 The yearly number of cardiac arrest events among competitive athletes was determined before and after the National Sport Law was enacted in Israel in 1997. This law mandates screening of all athletes with resting ECG and exercise testing. The average yearly incidences during the decade before the law and the decade after were 2.54 and 2.66 events per 100,000 person-years, respectively.

It comes down to this: Is extensive pre-participation screening a solution to a major problem? Or is the problem that we’re seeking simple solutions to a complex problem?

References:

1. Corrado D, Basso C, Pavei A, et al. Trends in sudden cardiovascular death in young competitive athletes after implementation of a preparticipation screening program. JAMA 2006;296:1593-601.
2. Thompson PD, Franklin BA, Balady GJ, et al. Exercise and acute cardiovascular events placing the risks into perspective: a scientific statement from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism and the Council on Clinical Cardiology. Circulation 2007;115:2358-68.
3. Wilson JM, Jungner YG. Principles and practice of mass screening for disease [in Spanish]. Bol Oficina Sanit Panam 1968;65:281-393.
4. Harris RP,  Helfand M, Woolf SH, et al. Current methods of the US Preventive Services Task Force: a review of the process. Am J Prev Med 2001;20:21-35.
5. Kaltman JR, Thompson PD, Lantos J, et al. Screening for sudden cardiac death in the young: report from a national heart, lung, and blood institute working group. Circulation 2011;123:1911-8.
6. Steinvil A, Chundadze T, Zeltser D, et al. Mandatory electrocardiographic screening of athletes to reduce the risk for sudden death: proven fact or wishful thinking? J Am Coll Cardiol 2011;57:1291-1296. http://content.onlinejacc.org/cgi/content/full/57/11/1291

Keywords: Athletes, Mammography, Public Health, Prostate-Specific Antigen, Quality of Life, Pain, Confidence Intervals, Electrocardiography, Mandatory Testing, Death, Sudden, Cardiac, Exercise Test

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