Familial Hypertrophic Cardiomyopathy (HCM)
Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease that affects one in 500 individuals in the general population and is characterized by increased muscle mass and disorganization of the heart muscle. The thickening of the heart muscle occurs more frequently in the wall separating the two ventricles and this can reduce blood flow to the heart and lead to less efficient pumping of blood and, as a consequence, an increased risk of sudden death. HCM is the leading cause of sudden death in adolescence.
Despite this genetic heterogeneity, HCM has a common basic expression: myocardial hypertrophy and risk of sudden death, the severity of which is variable and largely unpredictable. Findings from genetic studies show that HCM is caused by mutations in more than 11 genes that encode components of the contractile or adjacent Z-disc structure of heart cells or cardiomyocytes. Mainly involved are mutations in the gene that produces the myosin heavy chain (MYH7) and alterations in the myosin C-binding protein gene (MYBPC3).
Symptoms
Hypertrophic cardiomyopathy presents a heterogeneous clinical picture, while some patients are asymptomatic, other patients, even those from the same family, may present with chest pain, dyspnea or shortness of breath (especially on physical exertion), palpitations, dizziness, s & eacute; s & eacute; ness;While some patients are asymptomatic, other patients, even in the same family, may present with chest pain, dyspnea or shortness of breath (especially with physical exertion), palpitations, dizziness, syncope, fainting, lightheadedness, and changes in normal heart rhythm or arrhythmias. Less commonly, sudden cardiac arrest associated with intense exercise and sudden death may occur.
Disease management
As far as lifestyle is concerned, as this disease usually affects young people in the midst of sporting activity, it is advisable to limit the practice of highly competitive sports. If patients are asymptomatic, with mild hypertrophy and no other risk factor for sudden death, they should be oriented to recreational sports that do not require much physical effort and in a low-competitive environment.
Excessive consumption of alcohol or stimulants, dehydration and extreme temperatures (e.g. saunas and hot tubs) should be avoided.
Treatment depends on the severity of the symptoms and may include medications, surgical procedures (septal myectomy) and the use of an implantable defibrillator.
Genes analyzed
Bibliography
Finocchiaro G, Merlo M, Sheikh N, et al. The electrocardiogram in the diagnosis and management of patients with dilated cardiomyopathy. Eur J Heart Fail. 2020 Jul;22(7):1097-1107.
Jääskeläinen P, Soranta M, Miettinen R, et al. The cardiac beta-myosin heavy chain gene is not the predominant gene for hypertrophic cardiomyopathy in the Finnish population. J Am Coll Cardiol. 1998 Nov 15;32(6):1709-16.
Regitz-Zagrosek V, Erdmann J, Wellnhofer E, et al. Novel mutation in the alpha-tropomyosin gene and transition from hypertrophic to hypocontractile dilated cardiomyopathy. Circulation. 2000 Oct 24;102(17):E112-6.
Wilde AAM, Semsarian C, Márquez MF, et al. European Heart Rhythm Association (EHRA)/Heart Rhythm Society (HRS)/Asia Pacific Heart Rhythm Society (APHRS)/Latin American Heart Rhythm Society (LAHRS) Expert Consensus Statement on the state of genetic testing for cardiac diseases. J Arrhythm. 2022 May 31;38(4):491-553.