Also known as: Familial hypertrophic cardiomyopathy 4; genetic cardiomyopathy hypertrophic (HCM); Hereditary ventricular hypertrophy; Hypertrophic subaortic stenosis
Includes:
Familial hypertrophic cardiomyopathy type 4 – OMIM#115197 https://omim.org/entry/115197
Familial hypertrophic cardiomyopathy type 1 – OMIM#192600 https://omim.org/entry/192600
1. The disease:
Hypertrophic cardiomyopathy (HCM) is typically defined by the presence of unexplained left ventricular hypertrophy (LVH) with a maximum wall thickness ≥15 mm in adults or a z-score >3 in children. If there is a family history of HCM, or if genetic testing confirms that a relative has inherited the family’s pathogenic sarcomere variant, a maximum LV wall thickness ≥ 13mm supports diagnosis. Such LVH occurs in a non-dilated ventricle in the absence of other cardiac or systemic disease capable of producing the observed magnitude of increased LV wall thickness, such as pressure overload or storage/infiltrative disorders.
2. The symptoms:
Common symptoms include shortness of breath (particularly with exertion), chest pain, palpitations, orthostasis, presyncope and syncope. Lack of early signs or symptoms does not exclude the diagnosis.
- The clinical manifestations of HCM are highly variable, ranging from asymptomatic LVH to arrhythmias (atrial fibrillation as well as malignant ventricular arrhythmias) to refractory heart failure. Moreover, manifestations can vary even within the same family.
- Although LVH and a clinical diagnosis of HCM often become apparent during adolescence around the onset of puberty or during young adulthood, onset can be earlier (in infancy and childhood, some rare cases detected during pregnancy) or later in life.
3. Actions to take in case of early diagnosis
- Babies with a positive genetic test (having 1 pathogenic variant in heterozygosis in one of the related genes) should continue breastfeeding.
- Pathogenic variants in one of the genes encoding a component of the sarcomere are found in approximately 50%-60% of probands (adults and children) with a family history of HCM, and approximately 20%-30% of probands without a family history of HCM. Approximately 3%-5% of affected individuals have more than one sarcomere gene variant (either biallelic variants in 1 gene or heterozygous variants in >1 gene) although fewer than 1% will have more than one pathogenic or likely pathogenic variant.
- The diagnosis is based on genetic results, familial history, clinical signs, EKG, and echocardiogram.
- HCM is a lifelong condition that requires lifetime management and regular follow-up with a paediatrician specialist in cardiology, geneticist, and a multidisciplinary approach to care.
- The most import would be the cardiac surveillance and serial exams to evaluate the heart function and the necessity for pharmacological treatment.
- Genetic counselling is highly recommended for family planning and evaluation of at-risk first-degree family members.