Cardiomyopathies

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Cardiomyopathies are a group of different diseases in which the heart muscle is damaged. They can affect people of all ages, even children suffer from them. Due to the different forms of the disease, it is not possible to say which age group is particularly affected or whether cardiomyopathies are more common in men or women. However, many of these diseases occur more frequently in individual families because they are caused by genetic alterations.

Clinical picture

In all forms of cardiomyopathy the structure of the heart muscle tissue changes and the heart is no longer as efficient. In most cases there is an inappropriate thickening or dilatation of one or both chambers of the heart. This causes the heart to pump less efficiently. Cardiomyopathies can lead to heart failure and arrhythmia. In the course of the often serious disease, the impairment of the heart muscle progresses further and further. In people under the age of 55, myocardial diseases are the main cause of heart transplantation.

Since the heart can only pump to a limited extent, patients often have the typical symptoms of heart failure: they feel tired, weak and no longer able to perform as well. Fluid accumulation in the lungs and body tissues, for example in the arms and legs, can occur because the blood accumulates in veins and lungs. Depending on which heart muscle disease is present, the symptoms are differently pronounced. Also, when they occur depends on the type of myocardial disease; some go unnoticed for years.

Causes

Cardiomyopathies are caused by different factors. They are often genetic, although it is not always known which genes are altered. The American Heart Association (AHA) classifies cardiomyopathies into primary and secondary heart muscle diseases. Primary cardiomyopathies include genetic cardiomyopathies (for example, hypertrophic cardiomyopathies), mixed (genetic and acquired) cardiomyopathies (for example, dilated cardiomyopathies) and acquired primary cardiomyopathies (for example, as a result of myocarditis). Secondary cardiomyopathies arise from diseases that can affect the entire body. These include storage, metabolic or connective tissue disorders. Secondary cardiomyopathies can also be caused by the damaging effect of various substances (e.g. drugs, medicines, chemicals). A distinction is also made between ischemic and non-ischemic cardiomyopathies. Ischemic cardiomyopathies are caused by circulatory disorders in the heart, for example as a result of severely narrowed coronary vessels (coronary heart disease).

Two examples of cardiomyopathies:

Dilated cardiomyopathy

In dilated cardiomyopathy, the ventricles and atria are dilated. As a result, the heart can no longer pump properly and the patients suffer from the typical symptoms of heart failure: they are no longer able to perform their work, have difficulty breathing and water retention in the lungs and legs occurs. Heart rhythm disturbances and dizziness can also occur. Dilated cardiomyopathy is triggered by various events: For example, infectious myocarditis with bacteria, viruses or parasites or coronary heart disease. Genetic mutations are assumed to be present in about one third of cases, as they are more common in families. Drugs, especially chemotherapeutic agents, can also lead to the pathogenic remodelling processes in the heart. Despite comprehensive diagnostics, no clear cause can be found in some of the patients, who are then referred to as idiopathic dilated cardiomyopathy.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is also a common heart muscle disease and occurs in approximately one in 500 people, men and women are affected. The causes are inherited genetic changes. The probability that a child will inherit the predisposition for HCM from a sick parent is 50 percent. In hypertrophic cardiomyopathy, the heart muscle is thickened, usually affecting the left ventricle. HCM is divided into an obstructive and a non-obstructive form. In the obstructive form the thickened heart muscle causes an obstruction of the outflow of blood from the heart to the aorta. HCM often goes unnoticed, but can manifest itself as chest pain, shortness of breath or fatigue. In young people, especially athletes, it is the most common cause of sudden cardiac death.

Therapy

Since little is known about the development and course of the disease in many forms, the treatment of cardiomyopathy is mainly concerned with alleviating the symptoms. Especially in the obstructive form, there are numerous drugs (e.g. beta blockers), interventional procedures (sclerotherapy of thickened heart muscle tissue by injection of alcohol, septal ablation) and surgical interventions (surgical removal of heart muscle tissue, septal myectomy) available. If there is a risk of sudden cardiac death, the implantation of a cardioverter defibrillator may become necessary. Patients should avoid intensive physical exercise, but in consultation with the treating physicians, moderate physical exercise is possible and even recommended.

The DZHK Register TORCH contains medical and socio-demographic data of patients suffering from a heart muscle disease which is hereditary or caused by inflammation. Too little is still known about the exact mechanisms by which these diseases develop. At the end of 2017, the 20 centres involved in TORCH were able to complete the first phase, in which data and samples from 2,300 patients were collected over a period of three years. The scientists are now evaluating the data and thus creating the prerequisites for new therapies and better diagnostic possibilities for these cardiomyopathies.