Cardiomyopathy is a myocardial disease of unknown etiology, the main signs of which are cardiomegaly (an increase in the size of the heart) and/or heart failure. In this case, lesions of the valves, coronary arteries, systemic and pulmonary vessels are excluded.
Literally from the Greek cardiomyopathia can be translated as “heart muscle disease”. The term was proposed in 1957. Interest in this group of diseases arose in the 50s of the last century, when various cases of diseases in patients with heart failure began to be described. With the development of typical symptoms in patients, there was no clear cause of heart damage.
The trigger mechanism for the occurrence of cardiomyopathy was initially considered to be the process of inflammation in the heart, which could be triggered by viral, bacterial and autoimmune cell damage. Based on this theory, the administration of antibiotics, antiviral and anti-inflammatory drugs should have led to regression of damage and restoration of heart function. However, practice has not confirmed this.
The risk of developing cardiomyopathies is increased in people with burdened heredity, as well as after acute infectious diseases. For the appearance of secondary cardiomyopathies, it is important to have systemic autoimmune diseases, endocrine pathology (diabetes mellitus, thyrotoxicosis) and toxic factors.
Currently, the cause of the disease is considered to be a mutation of genes responsible for the operation of the complex of intracellular proteins of working myocardial cells — cardiomyocytes. Over 1,400 genes have already been identified, and research continues.
Primary cardiomyopathies are more often detected in childhood and young age, secondary ones are possible at any age.
If you find similar symptoms, consult a doctor. Do not self-medicate – it is dangerous for your health!
Symptoms of cardiomyopathy
There are no specific symptoms specific only to cardiomyopathy. It is this feature that makes it difficult to diagnose the disease early. Cardiomyopathy is asymptomatic or low-symptomatic for a long time, in the expanded stage it is similar in the clinic to the manifestations of coronary heart disease, various heart defects.
The first complaints that patients come to the doctor with are:
- shortness of breath with the usual loads and sometimes at rest;
- chest pain that occurs both during exercise and at rest;
- interruptions in the work of the heart;
- attacks of sudden palpitations;
- darkening of the eyes;
Often, the disease is detected during routine ECG recording during preventive examinations, however, it must be remembered that the first manifestation of the disease may be an unexpected (sudden) death that occurred for no apparent reason.
Pathogenesis of cardiomyopathy
In recent years, thanks to the possibilities of genetics, it has been established that the cause of many cardiomyopathies are genetic mutations that lead to the production of defective cardiomyocyte proteins. The development of a certain type of cardiomyopathy depends on which protein of the working myocardial cell (cardiomyocyte) has changed.
Previously, it was believed that cardiomyopathies occur due to inflammation in the heart, which is associated with cell damage by various viruses. However, studies have shown that only in some patients the development of cardiomyopathy is preceded by a viral disease. In this case, after acute myocarditis (inflammation of the heart muscle), multiple cardiomyocyte lesions occur. Some of them lose their functions, and instead of muscle contractile tissue, fibrous, low-elastic tissue appears. The preserved myocardium is forced to take over the work of dead cells and therefore also changes. As a result, there is a deformation of both the damaged areas of the myocardium and the remaining workers, which leads to a change in the anatomy of the heart. The walls and cavities of the heart are deformed, the valve rings are often stretched.
Similar changes also occur in hereditary metabolic disorders and lysosomal accumulation diseases (rare diseases in which the function of intracellular organelles of lysosomes is disrupted). Due to the congenital lack of enzymes that process carbohydrate-containing products, large molecules of glycogen, glycoprotein, etc. accumulate in the body, which damage the body. More than a hundred such diseases are known, but their prevalence is low. As a rule, they manifest themselves in childhood and at a young age and, in addition to heart damage, affect almost the entire body: bones, muscles, nervous system, vision and hearing. The most studied accumulation diseases are hemochromatosis, Piquet’s disease and Fabry’s disease.
There are special family forms of cardiomyopathy, so it is important to study the heredity of patients and collect a family history.
Problems often arise when examining athletes, because due to regular loads, their heart muscle compensatorily increases, and the so-called “sports heart” develops. Therefore, in such cases, accurate genetic tests are needed for reliable differential diagnosis, which are currently being developed. It is likely that with these factors there is a genetic defect that, with regular exercise, leads to the development of cardiomyopathy.
Classification and stages of cardiomyopathy development
As the information accumulated, the most common types of cardiomyopathy and their familial forms were identified:
Rare forms of cardiomyopathy also include systemic diseases and pathological conditions in which so-called secondary cardiomyopathies occur: diabetic, thyrotoxic, alcoholic, autoimmune and others.
Based on the cause of the disease, it becomes clear that cardiomyopathies can be either isolated – primary, or be part of a systemic disease, i.e., be secondary.
Clinical and morphological classification of primary cardiomyopathies:
- arrhythmogenic dysplasia of the right ventricle;
- rare forms of unclassifiable cardiomyopathies.
In hypertrophic cardiomyopathy, there is a pronounced, more often uneven increase in the myocardium of the left and / or less often the right ventricle. At the same time, the interventricular septum grows more often. It prevents the flow of blood from the heart to the aorta. This enlargement of the myocardium in hypertrophic cardiomyopathy appears for no apparent reason. It is known that the heart can increase due to prolonged hypertension, coronary heart disease, congenital and acquired heart defects.
Anatomical classification of hypertrophic cardiomyopathy depending on the localization:
I. Hypertrophy of the left ventricle:
- hypertrophy of the interventricular septum — 90 % of cases;
- mid-ventricular hypertrophy – ≈ 1 %;
- apical hypertrophy – ≈ 3%;
- hypertrophy of the lateral or posterior part of the interventricular septum ≈ 1 %.
Symmetrical, or concentric — ≈ 5%.
II. Hypertrophy of the right ventricle – less than 1%.
Depending on the presence of obstruction of the external tract of the left ventricle (the area between the interventricular septum and the anterior flap of the mitral valve) at rest and under load, two types of hypertrophic cardiomyopathy are distinguished:
- obstructive type – pressure gradient (difference in blood pressure indicators) in the external tract of the left ventricle > 30 mmHg;
- latent – pressure gradient increases with load > 30 mmHg;
- non-obstructive – pressure gradient < 30 mmHg at rest and under load.
Such variants and types of hypertrophic cardiomyopathy are important for choosing a patient’s treatment method, including surgical.
Dilated cardiomyopathy reveals stretching of all chambers of the heart and a decrease in its systolic function. At the same time, the force with which the heart pushes blood into the large circulatory circle decreases. Restrictive cardiomyopathy is a rare type of cardiomyopathy. With it, the elasticity of the myocardium is disrupted with the preserved systolic function of the heart. Most often this happens as a result of fibrous changes in the endocardium, subendocardium and myocardium, that is, with the growth of connective tissue. At the same time, the size of the heart remains normal or even decreases.
Restrictive cardiomyopathy can be idiopathic or secondary to other diseases, in particular to endomyocardial fibrosis, sarcoidosis and amyloidosis, and also develops within the framework of carcinoid syndrome, in which the production of vasoactive substances (serotonin, histamine, prostaglandins, bradykinin) is increased.
The types that are difficult to detect include arrhythmogenic dysplasia of the right ventricle, in which structural changes occur in the structure of the wall of the right ventricle — the replacement of cardiomyocytes with fibrous adipose tissue and the development of arrhythmia.
Unclassifiable cardiomyopathies: non-compact myocardium, stress-induced cardiomyopathy.
Secondary (specific) cardiomyopathies: with a known disease, the severity of heart damage is more pronounced and does not correspond to the cause:
- ischemic cardiomyopathy (due to ischemic heart disease);
- hypertensive cardiomyopathy;
- inflammatory cardiomyopathy as an outcome of myocarditis;
- metabolic cardiomyopathies (endocrine, familial accumulation diseases, vitamin deficiency);
- generalized systemic diseases (connective tissue pathology, infiltration and granulomas);
- muscular dystrophy in generalized myotonic dystrophy;
- neuromuscular disorders in ataxia (violation of the coordination of movements of various muscles);
- as a consequence of the toxic effects of alcohol, medications and radiation. If there is a clear link between the damaging factor and the development of cardiomyopathy, then it can be called toxic, drug or radiation cardiomyopathy;
- peripartal cardiomyopathy during pregnancy and after childbirth.
Complications of cardiomyopathy
Features of the course of cardiomyopathy are life-threatening. The disease can debut immediately with sudden death or life-threatening arrhythmias: ventricular fibrillation, ventricular tachycardia. A high risk of sudden cardiac death is associated with risk factors such as:
- family history (cases of sudden cardiac death due to hypertrophic cardiomyopathy);
- recorded frequent ventricular tachycardia;
- drop in blood pressure during exercise;
- the thickness of the muscle shadow of the left ventricle is more than 3 cm;
- extensive and diffuse late enhancement of gadolinium contrast on MRI.
With a more stable course, heart failure develops, which is difficult to respond to traditional drug therapy. Chronic heart failure can be suspected by the following signs:
- shortness of breath that occurs during exercise of varying intensity;
- increased fatigue when performing habitual activities;
- rapid heartbeat;
- the appearance of swelling on the legs by the end of the day.
With the aggravation of insufficiency, all the symptoms become more pronounced. There are five stages of heart failure:
- Stage I (HI) – initial – manifests itself in the form of shortness of breath and palpitations only with significant physical exertion.
- Stage II is a violation of hemodynamics with little physical exertion, sometimes at rest.
- Stage IIA — shortness of breath and palpitations with moderate physical exertion. Indistinct cyanosis. The appearance of a dry cough, sometimes hemoptysis, palpitations, interruptions in the heart area. The ability to work is noticeably reduced.
- Stage IIB – shortness of breath at rest. All objective symptoms of heart failure are sharply intensified: pronounced cyanosis, congestive changes in the lungs, prolonged aching pains, interruptions in the heart area. Signs of circulatory insufficiency in a large circle, permanent edema are added. Patients are incapacitated.
- Stage III (H III) – the final, dystrophic stage of insufficiency – irreversible changes in organs develop, metabolism is disrupted, exhaustion of patients develops. Treatment is ineffective.
Diagnosis of cardiomyopathy
It is not possible to identify any special signs characteristic of this disease when collecting complaints and examining the patient.
During a clinical examination, signs of heart failure of varying severity, arrhythmias attract attention, thromboembolic complications are possible.
Basically, cardiomyopathies are detected during echocardiography (ECHOCG) and electrocardiography (ECG). Additionally, radiopaque ventriculography and magnetic resonance imaging (MRI) with gadolinium contrast are used.
Echocardiography provides the most accurate information about the disease. This study is safe, accessible and is a routine method in cardiology. Thanks to ECHOCG, it is possible to determine the type of cardiomyopathy, the degree of thickening of the heart muscle, the presence of a permanent or transient obstruction to the blood flow from the outlet of the heart or stretching of its cavities. The method is indispensable for dynamic monitoring of patients, allows you to assess the prognosis and severity of the disease.
In modern cardiology, new methods of visualization of the heart and blood vessels are increasingly spreading — for example, magnetic resonance imaging (MRI). But its disadvantage is the high cost of equipment and low availability of the methodology due to the lack of high-quality equipment and specialists.
Changes in the form of signs of hypertrophy of the left ventricular myocardium, as well as signs of its overload and various cardiac arrhythmias can also be recorded on a standard ECG.
Holter ECG monitoring also records rhythm and conduction disturbances in almost 100% of cases. The detection of such rhythm disturbances affects the selection of basic therapy for cardiomyopathy.
In special cases, a lifetime myocardial biopsy is possible to clarify the diagnosis of rare forms of cardiomyopathy (for example, with amyloidosis). The technique is invasive, potentially dangerous for the patient, requires the use of a unique set of equipment and the highest qualification of specialists.
Of the laboratory diagnostic methods, in addition to standard blood tests (clinical and biochemical), it is necessary to note DNA diagnostics. It is the “gold standard” for suspected cardiomyopathy according to international (European and American) guidelines. At the moment, this approach is practically the only one that is applicable for early detection and prediction of the risk of developing familial forms of cardiomyopathy. In Russia, this level of diagnosis is possible in single laboratories and is an expensive procedure because of its uniqueness.
Treatment of cardiomyopathy
According to modern concepts, the patient’s treatment strategy is determined in the process of dividing patients into categories depending on the type of cardiomyopathy.
All patients with detected cardiomyopathy, regardless of the course of the disease (including asymptomatic), need dynamic monitoring. The frequency of observation and the scope of examinations are determined individually. The mandatory list includes standard tests (clinical and biochemical blood analysis), ECG, ECHOCG and Holter ECG monitoring.
Therapeutic tactics depend on many factors and are selected individually. At the same time, anatomical features are taken into account — obstruction of the external tract of the left ventricle, stretching of the heart cavities, the presence of valvular pathology, the stage of heart failure and also concomitant diseases. It is necessary to identify factors that increase the risk of sudden death and life-threatening arrhythmias.
General measures include the restriction of significant physical exertion and the exclusion of sports, which can cause further stress on the myocardium. But patients with cardiomyopathy do not require complete exclusion of physical exertion and bed rest. The level of loads, their frequency, intensity and duration are selected individually. It is shown to exclude alcohol consumption and tobacco smoking.
With dilated cardiomyopathy, it is necessary to treat the cause of the development of stretching of the heart cavities, if possible. In the drug therapy of heart failure, all standard groups of drugs are used:
- ACE inhibitors;
- angiotensin II receptor blockers;
- beta blockers;
- aldosterone receptor blockers;
For the treatment of severe heart failure, combined medications containing sacubitril and valsartan, as well as an implantable cardioverter defibrillator and/or cardiac resynchronization therapy are recommended. Oral anticoagulants are used in patients with cardiac arrhythmias.
In the treatment of obstructive cardiomyopathy, some groups of drugs have limitations (ACE inhibitors, angiotensin II receptor blockers), but beta-blockers and calcium channel blockers are used. If necessary, antiarrhythmic drugs are used.
In the treatment of restrictive cardiomyopathy, emphasis is placed on the treatment of the underlying disease that caused changes in the heart. It is possible to use diuretics.
In addition to medications, in some cases, surgical methods of treating cardiomyopathy are resorted to.
In hypertrophic cardiomyopathy, septal myectomy is used — excision of the myocardium located at the base of the interventricular septum. It can also be supplemented with an intervention on an altered mitral valve: valvuloplasty, mitral valve prosthetics and mitral valve ring correction.
In severe obstructive hypertrophic cardiomyopathy, an operation is considered — excision of a part of the heart muscle or a more gentle technique — percutaneous transluminal alcohol ablation. With it, up to 3 ml of 96% alcohol is injected through a catheter into the zone of maximum myocardial hypertrophy and its infarction is caused. Because of this, the muscle decreases in size, the obstacle (obstruction) to the blood flow through the mitral ring disappears. Next, a pacemaker is installed to synchronize the work of all parts of the heart. This procedure is performed by cardiac surgeons in specialized departments.
For some patients, a special type of cardiac stimulator — a defibrillator-cardioverter is installed to prevent arrhythmia, which ultimately prolongs their life.
And of course, in particularly difficult situations, the possibility of heart transplantation is being considered to save lives. A patient with a transplanted heart requires lifelong observation at a transplant center and taking a number of powerful drugs that affect the immune system.
The prognosis depends on the subtype of cardiomyopathy and the course of the disease. Due to the complexity of detection, there are no major studies on these types of diseases, data on life expectancy are only approximate.
The prognosis for dilated cardiomyopathy is unfavorable, but may improve with therapy. About a fifth of all patients die within the first year. From 40 to 50% of all deaths are sudden, as a result of malignant arrhythmia or embolism. The prognosis is better if, due to compensatory hypertrophy, the wall thickness of the ventricles is preserved, and worse if the walls are thinned.
The prognosis for hypertrophic cardiomyopathy is also unfavorable, but mortality is not so high — in the first year 1% of patients die, more often from sudden death due to risk factors (heredity, tachycardia, previous fainting, low blood pressure).
With restrictive cardiomyopathy, the prognosis is unfavorable, since the disease is often found at a late stage of development. Treatment is only symptomatic and supportive.
There is a certain percentage of patients with cardiomyopathy who live for a long time without clinical manifestations of this disease and almost as long as healthy people. Since the causes of cardiomyopathy are not fully understood, no special prevention has been developed at the moment. Prevention can be considered early diagnosis and regular medical examinations – annually at the therapist with ECG and standard tests. A cardiologist’s consultation and an echocardiogram will be able to confirm suspicions or rule out the disease.
For a person with detected cardiomyopathy, the frequency of visits and examinations is set individually.