Diagnosis of dilated cardiomyopathy

Diagnosis of dilated cardiomyopathy should be based on the exclusion of other causes of heart failure, such as coronary heart disease, congenital and acquired heart defects, and arterial hypertension.

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Diagnostic criteria for idiopathic (primary) dilated cardiomyopathy

• Left ventricular ejection fraction <45% and/or shortening fraction <25%, assessed by echocardiography, radionuclide scanning, or angiography.
• Left ventricular end-diastolic dimension >117% of predicted value adjusted for age and body surface area.
• Criteria for excluding the diagnosis of DCM.
• Systemic hypertension (>160/100 mmHg).
• Atherosclerotic lesion of the coronary arteries (stenosis >50% in one or more major branches).
• Alcohol abuse (>40 g/day for women and >80 g/day for men for more than 5 years after 6 months of abstinence).
• A systemic disease that could lead to the development of dilated cardiomyopathy.
• Diseases of the pericardium.
• Congenital and acquired heart defects.
• Pulmonary heart.
• Confirmed accelerated supraventricular tachycardia.

Patients typically describe the presence of various symptoms of heart failure that have been increasing over the past few months or years. Symptoms may appear before cardiomegaly is detected by echocardiography and chest radiography. It is important to actively clarify the fact of alcohol abuse, as it may play a role in the progression of primary dilated cardiomyopathy. During the general examination, signs of heart failure are determined: acrocyanosis, edema of the lower extremities, orthopnea, an increase in abdominal volume, swelling of the jugular veins.

When auscultating the lungs, moist, dull, fine-bubble rales may be heard in the lower sections.

Palpation of the heart reveals an increased, diffuse, leftward and downward shifted apical impulse. A diffuse and increased cardiac impulse and epigastric pulsation are often detected due to hypertrophy and dilatation of the right ventricle.

Percussion usually reveals a shift in the boundaries of relative cardiac dullness to the left and right due to dilation of the left and right ventricles, and upwards in the case of dilation of the left atrium. Absolute cardiac dullness may be expanded due to dilation of the right ventricle.

During auscultation of the heart, the first tone at the apex is weakened, and a protodiastolic gallop rhythm can also be heard at the apex (due to the appearance of the third tone), which is associated with volume overload of the ventricles. Characteristic are murmurs of relative insufficiency of the mitral and tricuspid valves. With the development of atrial fibrillation or extrasystole, the heart tones are arrhythmic.

For a more accurate assessment of the clinical condition of a patient with DCM and CHF, the Russian Clinical Assessment Scale (SHOKS) has been proposed, which contains 10 points. Questioning and examining the patient in accordance with the SHOKS points reminds the doctor of all the necessary studies that he must undertake to examine the patient. During the examination, the doctor asks questions and conducts studies corresponding to points from 1 to 10. The points are noted in the card, which are then summed up. I FC CHF corresponds to <3 points on the SHOKS scale, II FC - 4-6 points. III FC - 7-9 points, IV FC >9 points.

Scale for assessing the clinical condition in CHF (SHOKS) (modified by Mareev V.Yu., 2000)

• Shortness of breath: 0 - no, 1 - during exertion, 2 - at rest.
• Has your weight changed over the last week: 0 - no, 1 - increased.
• Complaints about irregular heartbeat: 0 no, 1 yes.
• What position is the patient in bed: 0 - horizontal, 1 - with the head end raised (two pillows), 2 - with the head end raised and wakes up from suffocation, 3 - sitting.
• Swollen neck veins: 0 - no, 1 - lying down, 2 - standing.
• Wheezing in the lungs: 0 - no, 1 - lower sections (up to 1/3), 2 - up to the shoulder blades (up to 2/3), 3 - over the entire surface of the lungs.
• Presence of gallop rhythm: 0 - no, 1 - yes.
• Liver 0 - not enlarged, 1 - up to 5 cm, 2 - more than 5 cm.
• Edema: 0 - none, 1 - pastosity, 2 - edema, 3 - anasarca.
• Systolic blood pressure level: 0 - >120 mmHg, 1 - 100-120 mmHg, 2 - <100 mmHg.

Laboratory studies of primary dilated cardiomyopathy do not reveal specific changes. They should be aimed at excluding secondary DCM: assessment of serum levels of phosphorus (hypophosphatemia), calcium (hypocalcemia), creatinine and nitrogenous bases (uremia), thyroid hormones (hypothyroidism or hyperthyroidism), iron (hemochromatosis), etc. Testing for HIV infection and hepatitis C and B viruses is mandatory.

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Instrumental diagnostics of dilated cardiomyopathy

• Chest X-ray

Cardiac enlargement, cardiothoracic ratio more than 0.5 - cardiomegaly, signs of pulmonary congestion, interstitial or alveolar edema.

• Resting ECG. Holter ECG monitoring.

Non-specific changes in the ST segment and T wave, decreased voltage of the waves, deformation of the complex, often sinus tachycardia, various rhythm and conduction disorders.

Detects episodes of tachycardia or bradycardia, especially indicated in the presence of syncopal and presyncopal episodes.

• Echocardiography. Two-dimensional (B and 20) and one-dimensional (M) modes.

They make it possible to assess the size of the chambers and the thickness of the walls of the heart, the presence or absence of blood clots in the cavities, the presence of effusion in the pericardial cavity, and also to quickly and accurately assess the systolic function of the right and left ventricles.

• Echocardiography. Doppler mode (pulse, continuous and color).

Most useful for diagnosing mitral regurgitation (detection and assessment of severity with calculation of pressure gradient on the valve under examination), systolic and diastolic myocardial dysfunction.

• Echocardiography. Dobutamine stress echocardiography.

It allows detection of areas of viable myocardium and cicatricial changes and can be useful in deciding on myocardial revascularization in some patients with coronary artery disease - more often for the purposes of differential diagnosis with ischemic dilated cardiomyopathy.

• Cardiac catheterization and angiography.

It is recommended for assessing the size of the heart cavities, determining the end-diastolic pressure in the left ventricle and left atrium, pulmonary artery wedge pressure and pulmonary artery systolic pressure, as well as excluding coronary artery atherosclerosis (CAD) in patients over 40 years of age, if there are corresponding symptoms or high cardiovascular risk.

• Endomyocardial biopsy.

More often, when inflammatory cardiomyopathy is suspected, the degree of destruction of muscle filaments and cellular infiltration of the myocardium can be assessed for the differential diagnosis of myocarditis and cardiomyopathy.

Example of diagnosis formulation

Idiopathic dilated cardiomyopathy. Atrial fibrillation, permanent form, tachysystole. NC II B, III FC.

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Differential diagnostics

Differential diagnostics are carried out with other forms of cardiomyopathy, and it is also necessary to exclude the presence of left ventricular aneurysm, aortic stenosis, chronic pulmonary heart disease, etc.

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