**3. Inheritance**

diagnosis. In borderline cases (≥13 mm), a thorough evaluation including family history is needed [1, 2]. In siblings, parents or children of a HCM patient, 13‐mm thickness is enough for diagnosis [1, 2]. In children and adolescents, a wall thickness more than two standard deviations in the corresponding age group should raise suspicion of the diagnosis of HCM [3]. An ultrasound of the heart, echocardiography, typically reveals the diagnosis of HCM. Echocardiography is usually readily available, but occasionally other imaging techniques are needed. Cardiac magnetic resonance (CMR), computed tomography (CT) or rarely positron emission tomography (PET) is sometimes used for diagnostic purposes or to gain additional information for optimal disease management [4]. The hypertrophied segment is almost always affecting the left ventricle even though right wall involvement does occur [1, 2]. Typically, the septal part is enlarged, eitherthe basal part orthe middle part, but could affect lateral, posterior and apical part, or a combination thereof [1]. A concentric hypertrophic is often associated with secondary causes of hypertrophy but does occur as HCM entity. If an isolated hypertro‐ phy solely involves the basal part of the septal wall in an elderly and no other signs or family history of HCM is found, often an explanation such as hypertension is the major cause [1, 2]. Even though the diagnosis of most cases of HCM is straight forward, careful attention to other causes and robust imaging techniques, including a cardiologist with expertise in the field, is warranted. Because HCM is a life‐long disease with consequences not only for the patient but

Dyspnoea is the predominant symptom of HCM that leads to evaluation with an echocardio‐ gram. Shortness of breath is pronounced at exertion due to relaxation disturbance of the left ventricle during diastole and/or outflow tract obstruction. This latter form is called hypertro‐ phic obstructive cardiomyopathy, and the obstruction is often dynamic with regard to filling pressure, heart rate and body position and affected by medications with effect on the cardio‐ vascular system. Often the patient has an adopted life style to decreased physical stamina, and often the diagnostic presentation is rather vague including tiredness. The HCM diagnosis is

A progressive HCM may sometimes lead to deterioration of the systolic function of the left ventricle. The ventricle dilates and hypertrophic segments remodel into dilatation, which sometimes can make it difficult to discern from other cardiomyopathies with dilated mor‐

Chest pain without coronary disease may also lead the physician to evaluate alternative diagnosis, and sometimes HCM is revealed. Microvascular dysfunction and fibrosis are part of the disease progression; biopsies show myocardial disarray, and modern PET imaging techniques confirm structural and functional abnormalities, which explain symptoms. However, biopsies are not indicated as part of routine evaluation as the same information would be gained non‐invasively [2, 4]. Syncope evaluation is sometimes the initial work‐up that leads to the diagnosis of HCM. The mechanisms could be either hemodynamic or cardiac

often delayed or sometimes misclassified from the initial diagnostic work‐up.

phology. This condition is called end stage and indicates a worse prognosis [5–8].

also for relatives, a correct diagnosis is indeed important.

**2. Symptoms and signs**

362 Cardiomyopathies - Types and Treatments

In more than half of the HCM cases, modern genetic panels can explain the cause of HCM and partly predict the outcome [12–14]. Of all mutations associated with HCM, the vast majority affects myosin proteins: beta‐myosin heavy chain (MYH7) and myosin‐binding protein (MYBPC3). Other components of the actin‐myosin filaments, such as troponins or tropomyo‐ sin, rarely explain disease [2]. However, there is a steady increase in disease causing mutations due to increased research activities and widened genetic panels in everyday practise.

The mutations of HCM are autosomal dominant with the exception of the X‐linked Danon disease due to lysosome‐associated membrane protein 2 [15]. The most common metabolic disease causing hypertrophy of the heart is Anderson‐Fabry, which is a storage dysfunction of the lysosomes. In children, hypertrophy of the heart is part of a syndrome, and constellations of malformations may lead suspicion towards Noonans disease, LEOPARD or even more rare diseases. In adults, amyloidosis should be part of the differential diagnosis. A correct molecular diagnosis can sometimes provide clinicians with specific treatment options and thus improve prognosis for the individual.

Family‐history taking is a compulsory part of the initial evaluation of a patient with a suspected or conformed hypertrophy. The clinician should systematically document the patients' report on family members who died suddenly or suffered from unexplained syncope or other symptoms suggesting an inheritance. This history taking may include not only first or secondary degree relatives and but also often tedious and administrative efforts to search for older documents, medical records, military service tests like ECG and autopsy protocols. In families who have members who moved to other regions or emigrated from the country, this can be especially challenging. A portion of detective abilities and a critical approach to information from historical medical records or a patients' explanation to a sudden death may be unmasked by a pedigree of suspected HCM. In these efforts, a specialized health care provider trained in history taking, administrative paths and updated knowledge of genetic counselling including bioinformatics will be valuable in conjunction with the cardiologist.
