KEY POINTS
■ Hypertrophic cardiomyopathy (HCM) is a genetic heart condition that is the most common cause of sudden death in young athletes. The condition is caused by an autosomal dominant mutation in genes coding for myosin heavy chains or proteins regulating calcium.
■ Italy implemented a preparticipation screening protocol in 1982 for all athletes aged 12 to 35 years who participate in officially sanctioned sports. The screening protocol includes personal and family history, physical examination, and resting and exercise 12-lead ECG. A cross-sectional study of the data from more than 25 years of implementation demonstrated that 12-lead ECG effectively identifies cardiac anomalies in young athletes.
■ The American College of Sports Medicine and the American Heart Association (AHA) recommend a complete cardiovascular history plus a physical examination. However, the AHA maintains that a 12-lead ECG should not be required in routine preparticipation screening. The AHA contends that precautionary ECGs tend to have a high false-positive rate and would therefore lead to additional diagnostic testing that can unnecessarily increase the average cost of screenings.
A wide variety of injuries commonly occur in people who participate in sports. A few of the more complex sports injuries include collateral and cruciate ligament tears, which can sideline an
athlete for up to 1 year. A cervical spine injury is a career-threatening injury that has the potential to leave an athlete paralyzed. However, most athletes would be hard-pressed to believe that any injury or health-related condition would be fatal, even when considering the more serious injuries. But did you know that a heart condition with the potential to cause death during rigorous exertion goes virtually unnoticed in most sports preparticipation screenings?
Hypertrophic cardiomyopathy (HCM) is a genetic heart condition that is the most common cause of sudden death in young athletes.1 The condition is caused by an autosomal dominant mutation in genes coding for myosin heavy chains or proteins regulating calcium.2 The real importance of HCM is its association with the risk of sudden death in athletes. The risk for sudden cardiac death is 2.8 times greater in young athletes compared with nonathletes.3 This concern makes the detection of HCM before athletes participate in competitive sports crucial. Ongoing debates regarding which diagnostic tests should be included in routine preparticipation screening to increase the likelihood of diagnosing a cardiac abnormality persist globally. The 12-lead ECG is considered to be a practical and efficient test for detecting hypertrophic heart changes, thereby potentially saving lives.4
MAKING THE DIAGNOSIS
Dyspnea and chest pain are the most common symptoms of HCM.5 After exertion, a syncopal episode is also commonly experienced and is often the only indication of HCM. The genetic mutation leads to hypertrophy of the left ventricular myocardium, particularly the interventricular septum.6 The ventricular chamber becomes smaller and diastolic filling is decreased as the left ventricular myocardium becomes hypertrophied. HCM can also obstruct the outflow of blood from the left ventricle. The enlarged interventricular septum (asymmetric septal hypertrophy) abuts the anteriorly displaced anterior leaflet of the mitral valve, thereby creating a dynamic obstruction.6 Left ventricular hypertrophy (LVH) coupled with the outflow obstruction increases the potential for arrhythmias and syncopal episodes when the body has a high demand for oxygen, such as during rigorous physical exertion.
Physical examination findings are frequently normal, and no significant history is elicited. A systolic murmur can be heard along the left sternal border in patients with HCM and an outflow obstruction.5 A loud S4 as well as a triple apical impulse may also be heard on auscultation, and a double impulse on palpation of the carotid pulse. Echocardiography, the diagnostic modality of choice, reveals asymmetric LVH and an interventricular septum that is 1.3 to 1.5 times thicker than the posterior wall (Figure 1). Furthermore, the left ventricular chamber is small and the wall demonstrates hypercontractility with delayed, incomplete filling during diastole. An ECG will show LVH in almost all symptomatic patients; however, 25% of all patients with HCM will have normal ECG results. Plain chest radiography findings are usually unremarkable. Cardiac MRI can confirm the presence of hypertrophy and scarring at the attachment of the right ventricle to the septum. Cardiac catheterization, also diagnostic for HCM, is the most invasive diagnostic modality.6