Sudden cardiac death in athletes.

Annotation: Any death of a young person is tragic; however, the sudden death of a young athlete is a particularly devastating event within a community. Emotions raised by these incidents include sorrow for the young person's death, fear of our own mortality, incredulity at the loss of a seemingly healthy individual, and anger. These events beg for an explanation as to why these deaths occur, and how they can be prevented. In this article, Dr. Leski presents the demographics and etiology for sudden death in young athletes and briefly discusses the process of screening athletes before athletic participation. Although these deaths are rare, they often garner great attention and produce great controversy, especially concerning the use of screening tools such as echocardiogram. At this time, the use of echocardiography as a routing screening tool does not appear justified; however, the use of electrocardiography in the athletic population will certainly change as technology improves and our understanding of these deaths improve. In addition, as Dr. Leski mentions, the use of genetic markers may be the next great step toward preventing these tragic events.

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In today's high-profile nature of sports, nothing garners the attention of enthusiasts like the sudden death of an athlete. Even at the high school level, communities are devastated when a student dies suddenly during athletic participation. At first glance, these tragic events seem to happen frequently, but upon further scrutiny, they are actually rare. The incidence of sudden cardiac death in high school athletes is reported to be about 1:180,000 with deaths in males being five times more prevalent than in females. For the general population, the incidence of sudden cardiac death during exercise has been reported as low as 1:18,000 and as high as 1:3,600. When postmortem studies were performed, congenital cardiac abnormalities were usually responsible for deaths occurring in those athletes less than 35 years old, and, of those cases, hypertrophic cardiomyopathy accounted for about 36% of the total (Table 1). However, in sudden cardiac death over the age of 35, coronary heart disease was responsible for 80% of the cases.

The problem with sudden cardiac death is that there are often no signs or symptoms of the impending event. The preparticipation examination is usually normal. However, any symptoms such as palpitations, severe dyspnea, chest pain, syncope with exertion, or a family history of sudden cardiac death before the age of 50, should warrant further cardiac workup (Table 2) that may include electrocardiogram (ECG), echocardiogram, and exercise stress test. A stress echo may actually give more information about wall-motion abnormalities during the demands of exercise. Physical findings such as irregular heart rhythms, any diastolic murmur, systolic murmurs that increase with Valsalva or decrease in the supine position, and findings consistent with Marfan syndrome (Table 3) should also be treated as indicators for further cardiac workup.

Currently, we have no good screening tool to look for potentially lethal conditions in young athletes. However, a routine ECG has been shown to be more sensitive than the history and physical examination in identifying possible abnormalities. The problem with the ECG is that many changes found on the ECG, including sinus bradycardia, early repolarization, and voltage criteria for left ventricular hypertrophy, can be related to the "athletic heart syndrome" which is a set of normal adaptations that the heart undergoes in response to exercise. Because of these findings, the ECG is not very specific for cardiac problems in the athletic population and may result in unnecessary and expensive workups. Therefore, ECG is not routinely used as a screening tool. The echocardiogram is another potentially useful screening tool, but it is somewhat time-consuming and expensive. The prevalence of hypertrophic cardiomyopathy found with echocardiogram in the general population is about 1:500. If the incidence of sudden cardiac death is 1:180,000, then there must be variable expressions of hypertrophic cardiomyopathy, with many being nonlethal forms of the disease. Therefore, screening echocardiograms may result in the exclusion of many children from an active lifestyle unnecessarily. On the horizon is the possible use of genetic markers, but these tests are not ready for general clinical practice. Truly, there is a dilemma when trying to resolve the issue of screening for conditions responsible for sudden cardiac death. Clearly, more research is necessary.

Each problem that I solved became a rule which served afterwards to
solve other problems.
--Rene Descartes

Table 1. Etiology of sudden cardiac death in people
[less than or equal to]35 years of age

Hypertrophic cardiomyopathy                 36%
Coronary anomalies                          19%
Cardiac mass                                10%
Aortic rupture                               5%
Tunneled left anterior descending (LAD)      5%
Aortic stenosis                              4%
Myocarditis                                  3%
Dilated cardiomyopathy                       3%
Arrhythmogenic right ventricular dysplasia   3%
Mitral valve prolapse                        2%
Coronary artery disease                      2%
Other                                        6%

Table 2. History and physical findings requiring further cardiac workup

Historical findings  Sudden cardiac death of a family member before the
                       age of 50
                     Palpitations during exercise
                     Dyspnea with exercise
                     Chest pain with exercise
                     Syncope or near syncope with exercise
Physical findings    Abnormal heart rhythms
                     Diastolic murmurs
                     Systolic murmurs that increase with Valsalva or
                       decrease in the supine position
                     Asymmetric pulses
                     Findings consistent with Marfan syndrome

Table 3. Physical findings in Marfan syndrome

Skeletal        Arm span > height
                Arachnodactyly
                Ligament laxity
                Kyphosis
                Pectus excavatum
                High arched palate
Cardiovascular  Aortic insufficiency murmur
                Mitral valve prolapse
Ophthalmologic  Lens dislocation
                Myopia

Accepted May 21, 2004.

Suggested Reading

Macknight JM, Ed. Cardiopulmonary Issues in Athletes. Clin Sports Med 2003;22(1).

Mark Leski, MD

From Lexington Family Practice, Lexington, SC.

Reprint requests to Mark Leski, MD, Lexington Family Practice, 122 Powell Drive, Lexington, SC 29072.