Hypertrophic cardiomyopathy

Hypertrophic Cardiomyopathy (HCM) is a heart muscle disease characterized by the presence of increased thickness of the walls of the left ventricle (LV) (left ventricular hypertrophy) not secondary to arterial hypertension, heart valve disease or other causes that can generate an increase in wall thickness. The thickness of the walls of the left ventricle is increased in some areas or in a diffuse manner.

Treatment and management
Evolution
Useful information and resources

General description of the pathology

In the majority of patients, Hypertrophic Cardiomyopathy is caused by one or more genetic mutations that can be identified, with current techniques, in about 60% of familial cases, in the genes that produce contractile proteins of the sarcomere (Myosin-binding Protein C, Myosin, Troponin). In these cases, HCM is defined as “sarcomeric”. In about 5% of familial cases, two mutations can be identified in the same gene or in two different genes.

Its prevalence in the general population is about 2 per thousand. But since it mostly develops slowly and progressively after adolescence, the prevalence is lower in pediatric age and much higher, up to 5 per thousand, or 0,5%, in adults, especially between 30 and 60 years. Consequently, it is not considered a rare disease. In females, the development of hypertrophy occurs later, even in the sixth or seventh decade of life.

Normal heart

Heart with hypertrophic cardiomyopathy

Symptoms

Initially, CMI is often asymptomatic, meaning that the symptoms may be absent or not perceived by the patient and the diagnosis in these cases is made through random checks such as during a sports medical examination. The most common symptoms, when present, are:

Palpitations
Difficulty making efforts such as climbing stairs due to shortness of breath – Dyspnea

Chest pain at rest or on exertion – Angina
Sudden loss of consciousness – Syncope

The course of hypertrophic cardiomyopathy may be worse in late-onset cases in women, as well as in patients who have had HCM since childhood.

Diagnosis

The diagnosis of HCM in adults is made when the thickness of even a single wall of the LV is equal to or greater than 15 mm, measured with echocardiography or magnetic resonance imaging. In the presence of mild hypertrophy (13–14 mm), the diagnosis of Hypertrophic Cardiomyopathy can be made if there are also major ECG abnormalities and/or genetic mutations considered responsible for the hypertrophy and/or at least one family member who has or has had HCM.

To make the diagnosis, it is necessary to perform non-invasive clinical and instrumental tests:

Medical visit
Basic electrocardiogram
Echocardiogram

Further investigations are then carried out, which include:

Blood chemistry tests
Dynamic ECG for 48 hours

Stress or cardiorespiratory test
Magnetic resonance imaging with contrast medium

These tests allow us to evaluate the severity of the heart disease and the risk of developing any complications.

From the Video Library of the Heart

Video insights on the diagnosis of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy. Differential diagnosis

Hereditary diseases of the myocardium

To confirm the precise diagnosis, a genetic test is performed, which can also provide indications regarding the therapy to adopt.

Once the presence of cardiomyopathy has been confirmed and the mutation has been identified, the presence of the same in family members can be verified through cascade screening.

Genetic Test
Genetics Thematic Sheet
Video library – Genetics in cardiomyopathies

Treatment and management

Once the diagnosis is made, it is necessary to try to identify the cause of the hypertrophy and distinguish sarcomeric HCM from other Cardiomyopathies such as Syndromic and metabolic forms at birth, mitochondrial or glycogen storage forms, and in adults Fabry disease, and cardiac amyloidosis. The results of the diagnostic tests, together with those of the genetic test, performed with the patient's consent after having carried out genetic counseling, can establish, with sufficient accuracy, the specific genetic cause of HCM and the most appropriate therapy.

The aim of therapy is to mitigate or eliminate symptoms and reduce the risk of complications. Therapy may be different, based on the specific genetic mutation that causes Hypertrophic Cardiomyopathy. The results of diagnostic tests, together with those of the genetic test, performed with the patient's consent after genetic counseling, can establish, with sufficient accuracy, the specific genetic cause of HCM and the most appropriate therapy. The aim of therapy is to mitigate or eliminate symptoms and reduce the risk of complications. Therapy may be different, based on the specific genetic mutation that causes Hypertrophic Cardiomyopathy.

Evolution of the pathology

CMI can change over time: the wall thicknesses tend to decrease, while the diameters of the left atrial cavity and the left ventricle increase by one or more centimeters over time (“remodeling”). Scar areas, composed of fibrotic tissue, may appear within the walls of the LV, which can be highlighted and then observed over time with MRI with contrast. The extent of hypertrophy varies, from mild (15-20 mm) to extreme forms, with widespread thicknesses of up to 4 cm.

Hypertrophy may be present only in the interventricular septum, that is, the portion of muscle that separates the two ventricles (asymmetric septal hypertrophy), but it may also extend to all the walls (concentric hypertrophy). In about 10% of patients, it is localized at the midventricular level (midventricular CMI), while localization at the apex of the heart (apical CMI) is frequent in Asians (25%) and rare in Europeans (7%).

Do you need help?

If you or a family member have been diagnosed with Hypertrophic Cardiomyopathy, AICARM is at your side. Our “Listening Hearts” service offers information, guidance and support to those living with this disease.

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