Can electrocardiographic screening prevent sudden death in athletes? NoBMJ 2010; 341 doi: https://doi.org/10.1136/bmj.c4914 (Published 14 September 2010) Cite this as: BMJ 2010;341:c4914
- Roald Bahr, professor in sports medicine
- 1Oslo Sports Trauma Research Center, Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway
Some facts are undisputed. Every year, athletes die tragically during exercise. Although regular physical activity is beneficial for most, vigorous exercise transiently increases the risk of sudden cardiac death in people with underlying cardiovascular disease—for example, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, ion channelopathies, or coronary artery anomalies.1 Sudden death during exercise is often the first manifestation of heart disease.2 Screening with 12-lead electrocardiography can identify some people with underlying heart disease.3 4
Proponents argue that these facts support making electrocardiographic screening a prerequisite for participation in organised sports to prevent sudden death.5 The cornerstone of their argument is a 25 year prospective study (1979-2004) from the Veneto region in Italy. This showed that the introduction of a mandatory screening programme for all athletes aged between 12 and 35 who wanted to participate in organised sports reduced the annual incidence of sudden cardiac deaths among athletes by 89%, while the incidence for non-athletic people of the same age remained unchanged. The main explanation was that athletes with cardiomyopathies were screened out of competitive sports, and deaths attributed to cardiomyopathies decreased.6
Criteria for screening
Screening is a public health strategy to detect a disease in individuals without signs or symptoms of that disease. The goal is to enable earlier intervention and thus reduce future morbidity and mortality. Although screening may lead to an earlier diagnosis, not all screening programmes are beneficial. The World Health Organization developed the Wilson-Jungner criteria for appraising a screening programme.7
Although WHO says all 10 criteria must be met, two criteria are particularly important. The first is that the condition being screened for is an important health problem (which depends not only on how serious the condition is but also how common it is), and the second is that a suitable screening test is available to detect early disease with acceptable sensitivity (detects all those with increased risk) and specificity (detects only those with increased risk).
Evidence from Norway
Let us consider the arguments for electrocardiographic screening using these criteria as the yardstick and Norway as an example. Should national electrocardiographic screening for athletes be mandatory?
Firstly, what is the size of the problem? Norway’s population of about 4.9 million is fairly active. Norwegian adolescents, for example, were found to be the most active among nationally representative samples from Denmark, Norway, Estonia, and Portugal.8 An eight year review (1990-7) of sudden death from the Norwegian Cause of Death Registry found 23 exercise related deaths among 15-34 year olds—that is, an average of three a year.9 The population at risk is difficult to estimate, but many of those who died were not involved in competitive exercise. In fact, there were no deaths of elite athletes during this period. Thus, the authors estimate the population at risk is about 325 000, corresponding to 0.9 deaths/100 000 a year, an incidence in the mid-range of rates reported in previous studies.9
The implication is that 325 000 Norwegians would need to be screened routinely to save three deaths a year, assuming that everyone at risk can be identified and all deaths prevented.
So can everyone at risk be identified? The overall sensitivity of electrocardiographic screening to detect any cardiovascular disease in asymptomatic athletes seems to be about 50%.3 However, the diagnostic accuracy varies among conditions. Although the sensitivity for cardiomyopathies is acceptable, other conditions, such as coronary atherosclerosis or coronary anomalies, are likely to be remain undetected. The conditions that cause sudden cardiac death also differ substantially between populations, with myocardial infarction and coronary atherosclerosis accounting for half of exercise related sudden deaths in Norway.9
In fact, no more than one third of the deaths observed in the Norwegian study could have been detected by electrocardiographic screening—that is, only one of the three deaths that occur each year. This contrasts with Italy, where arrhythmogenic right ventricular cardiomyopathy dominates,1 and the United States, where hypertrophic cardiomyopathy is the leading cause of sudden death.10 In other words, a screening programme that has successfully captured cardiomyopathies in Italy, will not necessarily be effective in Norway, where this seems to be a rare cause of sudden death.
Another factor to consider is that the false positive rates of screening can be as high as 40%.3 This is partly because of the grey area between potentially malignant electrocardiographic changes and physiological adaptations to intensive training. Although a recent study showed that including electrocardiography in cardiovascular screening increases sensitivity, the cost is reduced specificity (false positive rate 16.9% versus 5.5% for history and examination alone).11 US studies of high school athletes found 10% had abnormalities detected by electrocardiography that required specialist examinations.12 13 If we use this conservative estimate, as many as 36 000 Norwegians would need further follow-up (usually echocardiography, sometimes cardiac magnetic resonance imaging) to rule out underlying cardiovascular disease.
Electrocardiographic screening of athletes fails accepted public health criteria for screening programmes on several counts. Although sudden cardiac death is tragic, it is also rare. The diagnostic accuracy is also low and depends on which cardiac conditions are the main causes of sudden death in the population being screened. The recent US recommendations are right.10 Screening of hundreds of thousands of athletes to save possibly only one life a year, as would be the case in Norway, cannot be justified.
Cite this as: BMJ 2010;341:c4914
Competing interests: The author has completed the unified competing interest form at www.icmje.org/coi_disclosure.pdf (available on request from him) and declares that the Oslo Sports Trauma Research Center has been established through grants from the Royal Norwegian Ministry of Culture, the South-Eastern Norway Regional Health Authority, the International Olympic Committee, the Norwegian Olympic Committee and Confederation of Sport, and Norsk Tipping AS; he has had no relationships with any company that might have an interest in the submitted work in the past three years; he has no non-financial interests that may be relevant to the submitted work.
Provenance and peer review: Commissioned; not externally peer reviewed.