Cardiomyopathies are characterized by ventricular enlargement, thickness or stiffness. According to the WHO classification, diseases of unknown origin (cardiomyopathies) are distinguished from heart muscle diseases with known origin or having a relationship with other organ systems (specific heart muscle diseases). Cardiomyopathies are characterized by a worsening of cardiac work resulting from failure of the pump function and ventricular compliance or from severe arrhythmias. Consequences in prognosis and work capacity depend on the degree of heart failure and arrhythmias.