Dilated cardiomyopathy I42.0

Myocardial dysfunction characterized by ventricular dilatation, initially of the left ventricle, and in the final stage also of the right ventricle, by a decrease in systolic pumping force and a progressive loss of the ejection capacity of the heart. Furthermore, there are disturbances of the diastolic function. The heart loses elasticity, which in turn leads to a reduced filling of the heart cavities.

Primary (idiopathic) dilated cardiomyopathy (about 50% of DCM cases)

Secondary (specific) dilated cardiomyopathy (sequelae of different diseases or noxae; see below etiology)

The most common causes of childhood DCM are genetic and post-myocardial forms, metabolic causes and other secondary cardiomyopathies

Incidence 6/100,000 per year; prevalence: 40/100,000; m:w=2:1.

Etiopathogenesis of DCM (n. Felker GM et al. 2000)

Idiopathic - 50% of cases. The majority of idiopathic DCM cases are caused by mutations (hereditary or spontaneous). In contrast to hypertrophic cardiomyopathy (gene mutations of the sarcomere), mutations affect mainly structural proteins of the cytoskeleton (titin, dystrophin, laminin A, laminin C). Examples are: Duchenne muscular dystrophy (X-linked recessive hereditary DCM by mutation of the dystrophin gene), Curschmann-Steinert myotonic dystrophy (mutation in the dystrophia myotonica protein kinase gene on chromosome 19q13.2-13-3), autosomal recessive hereditary DCM by mutation of fatty acid oxidation genes.

Infectious - 9% of cases: viral (dilated HIV cardiomyopathy with poor prognosis, Coxsackie virus, influenza viruses, adenoviruses, echoviruses), bacterial (staphylococci, enterococci, Borrelia burgdorferi - about 10% of patients with chronic Lyme disease suffer from myocarditis which, if left untreated, can lead to dilated cardiomyopathy), fungal or protozoan (toxoplasmosis, Chagas disease: most frequent cause of DCM in Central and South America. Causes an acute myocarditis that turns into DCM in the final stage)

Ischemic - 9% of cases (myocardial infarction, microangiopathy)

Toxic -3% of cases (alcohol, cocaine)

Medicinal: (Chemotherapeutics: e.g. anthracycline, adriamycin, trastuzumab = monoclonal Ak against ErbB-2 receptor in breast cancer; anti- EGF drugs such as sunitinib)

Immunological(SLE, panarteriitis nodosa, systemic scleroderma, dermatomyositis)

Valvular: cardiac dysfunction in advanced vitae

Other: metabolic (beri-beri, malnutrition), sleep apnea, endocrine (hypo- or hyperthyroidism, pheochromocytoma, acromegaly), peripartal cardiomyopathy: rare cause, in the last month of pregnancy or up to 5 months after birth.

In children, the peak of diagnostic frequency is in infancy. It is the most common indication for heart transplantation in childhood.

In the foreground, by reducing the ejection fraction of the left ventricle (reduction to 30% of normal ejection), are the clinical symptoms of heart failure with dyspnoea, peripheral paleness or cyanosis, fatigue and peripheral edema. Dilatation of the heart results in relative mitral or tricuspid regurgitation. A systolic noise due to AV valve regurgitation and a 3rd and 4th heart tone are described auscultatorily (galloping rhythm). The pulse amplitude is small. In DCM, there is an increased tendency to systemic embolisms due to the disturbed hemodynamics.

Pathologically and anatomically the endocardium in the left and also partly in the right ventricle is often focally or diffusely grey-white thickened. In 50% of cases parietal thrombi are present, especially in the apex and trabecular region of the left ventricle. An endocardial thickening can be very prominent, especially in children, can be seen as a leading feature and worsens the prognosis. The coronary arteries show no changes.

X-ray image: cardiomegaly, possibly congestion of the lungs.

ECG: non-specific changes; partly flat, partly negative T waves; occasionally low voltage is recognizable. Heart actions are often arrhythmic; spectrum ranges from ventricular to supraventricular arrhythmias to atrial fibrillation (20-30%) with simultaneous left bundle branch block (20%).

Echocardiography: gives information about the extent of dilatation (primarily of the left, later also of the right ventricle), contractile dysfunction of the reduced ejection fraction. Ventricular hypokinesia or also abnormal segmental wall movements. Pulmonary hypertension can be assessed.

MRI: Possible intravital evidence of cardiac fibrosis (gadolinium enhanced MRI; so-called late enhancement).

Cardiac catheter: Detection of a low cardiac output as well as the increased peripheral resistance and pulmonary hypertension.

Biopsy: Changes are non-specific. Myocyte nuclei are hyperchromatic and enlarged. Fiber diameters appear rather reduced. Intramurally, there are more diffuse fibrosis areas and, less frequently, scars with particularly subendocardial accentuation. Degeneration of muscle cells in the form of myocytolysis and muscle fibre necrosis with empty sarcoleptic tubes, which may be surrounded by macrophages and mononuclear cells, is frequently observed.

The individual treatment depends on the respective cause.

General measures: Physical protection, if possible no cardiotoxic noxious substances.

Guideline-based therapy for heart failure. Thrombosis prophylaxis.

In progressive and severe heart failure, cardiac resynchronization therapy, implantable cardioverter defibrillator (ICD), repair of moderate to severe valve insufficiency. Ultima ratio: heart transplantation.

In children, DCM causes cardiac death in 4-8% of cases. Symptoms usually occur in children between the 1st and 6th month of life and in 50% of cases within the 1st year of life (often after infections). Letality is highest within the 1st year of life and lowest at the age of 1-14 years. Spontaneous remissions in 25-30% of patients.

Many DCM patients suffer sudden cardiac death without having previously become clinically apparent. The lethality rate is 35% within the first 5 years after diagnosis, 35% in pre-diagnosed patients and 70% within 10 years.

1. Eberli FR (2017) Cardiac dyspnea. In E. Battegay E (ed.) Differential diagnosis of internal diseases. Georg Thieme Publishing House, Stuttgart-New York S. 281-283
2. Felker GM et al (2000) Underlying causes and long-term survival in patients with initially unexplained cardiomyopathy. N Engl J Med 342):1077-1084.
3. Deliu RC et al (2017) Changes of desmin expression pattern in the myocardium of patients with alcoholic dilated cardiomyopathy.Rome J Morphol Embryol 58:1309-1315.
4. Salman OF et al (2018) Inherited Cardiomyopathies and the Role of Mutations in Non-coding Regions of the Genome. Front Cardiovasc Med 5:77.