Although HCM may be asymptomatic, affected individuals may present with symptoms ranging from mild to critical heart failure and sudden cardiac death at any point from early childhood to seniority. HCM is the leading cause of sudden cardiac death in young athletes in the United States, and the most common genetic cardiovascular disorder. One study found that the incidence of sudden cardiac death in young competitive athletes declined in the Veneto region of Italy by 89% since the 1982 introduction of routine cardiac screening for athletes, from an unusually high starting rate. As of 2010, however, studies have shown that the incidence of sudden cardiac death, among all people with HCM, has declined to one percent or less. Screen-positive individuals who are diagnosed with cardiac disease are usually told to avoid competitive athletics. HCM can be detected with an echocardiogram (ECHO) with 80%+ accuracy, which can be preceded by screening with an electrocardiogram (ECG) to test for heart abnormalities. Cardiac magnetic resonance imaging (CMR), considered the gold standard for determining the physical properties of the left ventricular wall, can serve as an alternative screening tool when an echocardiogram provides inconclusive results. For example, the identification of segmental lateral ventricular hypertrophy cannot be accomplished with echocardiography alone. Also, left ventricular hypertrophy may be absent in children under thirteen years of age. This undermines the results of pre-adolescents’ echocardiograms. Researchers, however, have studied asymptomatic carriers of an HCM-causing mutation through the use of CMR and have been able to identify crypts in the interventricular septal tissue in these people. It has been proposed that the formation of these crypts is an indication of myocyte disarray and altered vessel walls that may later result in the clinical expression of HCM. A possible explanation for this is that the typical gathering of family history only focuses on whether sudden death occurred or not. It fails to acknowledge the age at which relatives suffered sudden cardiac death, as well as the frequency of the cardiac events. Furthermore, given the several factors necessary to be considered at risk for sudden cardiac death, while most of the factors do not have strong predictive value individually, there exists ambiguity regarding when to implement special treatment. United States There are several potential challenges associated with routine screening for HCM in the United States. First, the U.S. athlete population of 15 million is almost twice as large as Italy's estimated athlete population. Second, these events are rare, with fewer than 100 deaths in the U.S. due to HCM in competitive athletes per year, or about 1 death per 220,000 athletes. Lastly, genetic testing would provide a definitive diagnosis; however, due to the numerous HCM-causing mutations, this method of screening is complex and is not cost-effective. Therefore, genetic testing in the United States is limited to individuals who exhibit clear symptoms of HCM, and their family members. This ensures that the test is not wasted on detecting other causes of ventricular hypertrophy (due to its low sensitivity), and that family members of the individual are educated on the potential risk of being carriers of the mutant gene(s). Canada Canadian genetic testing guidelines and recommendations for individuals diagnosed with HCM are as follows: * The main purpose of genetic testing is for screening family members. * According to the results, at-risk relatives may be encouraged to undergo extensive testing. * Genetic testing is not meant for confirming a diagnosis. * If the diagnosed individual has no relatives that are at risk, then genetic testing is not required. * Genetic testing is not intended for risk assessment or treatment decisions. * Evidence only supports clinical testing in predicting the progression and risk of developing complications of HCM. For individuals suspected of having HCM: * Genetic testing is not recommended for determining other causes of left ventricular hypertrophy (such as "athlete's heart", hypertension, and cardiac amyloidosis). * HCM may be differentiated from other hypertrophy-causing conditions using clinical history and clinical testing. UK A post-mortem following the death of TV presenter David Frost in 2013 found he had HCM, though it did not contribute to his death and his family was not informed. The sudden cardiac death of his 31-year-old son in 2015 led the family to collaborate with the British Heart Foundation to raise funds for better screening.
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