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For further information, see CMDT Part 10-44: Dilated Cardiomyopathy

Key Features

Essentials of Diagnosis

  • Symptoms and signs of heart failure

  • Echocardiogram confirms left ventricular (LV) dilation, thinning, and global dysfunction

  • Severity of right ventricular (RV) dysfunction critical in long-term prognosis

General Considerations

  • Categorized as heart failure with reduced ejection fraction where the LV ejection fraction (EF) is defined as ≤ 40%

  • Characterized by reduced myocardial contractility in the absence of abnormal loading conditions such as with hypertension or valvular disease

  • Causes

    • Familial in up to 20–35% of cases

    • Idiopathic in a large proportion

    • Endocrine, inflammatory, and metabolic causes include

      • Obesity

      • Diabetes

      • Thyroid disease

      • Celiac disease

      • Systemic lupus erythematosus

      • Acromegaly

      • Growth hormone deficiency

    • Nutritional diseases, such as deficiency of thiamine, selenium, and carnitine

    • May also be caused by prolonged tachycardia either from

      • Supraventricular arrhythmias

      • Very frequent premature ventricular contractions (PVCs) (> 15% of heart beats)

      • Right ventricular pacing

    • Also associated with HIV, Chagas disease, rheumatologic disorders, iron overload, sleep apnea, amyloidosis, sarcoidosis, chronic alcohol usage, end-stage renal disease, or cobalt exposure ("Quebec beer-drinkers cardiomyopathy")

Demographics

  • Prevalence averages 36 cases/100,000 in the United States and accounts for approximately 10,000 deaths annually

  • Blacks are afflicted three times as often as whites

Clinical Findings

  • Gradual development of heart failure symptoms in most patients

  • Rales

  • Elevated jugular venous pressure (JVP)

  • Cardiomegaly

  • S3 gallop rhythm

  • Murmurs of functional mitral or tricuspid regurgitation

  • Peripheral edema

  • Ascites

  • Cheyne-Stokes breathing, pulsus alternans, pallor, and cyanosis may be present in severe heart failure

Diagnosis

Imaging

  • Chest radiograph reveals

    • Cardiomegaly

    • Evidence of left and/or right heart failure

    • Pleural effusions (right more frequently than left)

  • Cardiac MRI

    • Diagnostic study of choice for right ventricular dysplasia

    • Helpful in identifying inflammatory or infiltrative processes, such as sarcoidosis or hemochromatosis

    • MRI with gadolinium can also help define an ischemic etiology by noting gadolinium hyperenhancement consistent with myocardial scar from infarction or prior myocarditis

Diagnostic Studies

  • ECG

    • ST–T changes, conduction abnormalities, ventricular ectopy

    • Sinus tachycardia is common

    • Other common abnormalities include left bundle branch block and ventricular or atrial arrhythmias

  • Echocardiogram

    • Indicated to exclude unsuspected valvular or other lesions and confirm the presence of ventricular dilatation, reduced LV systolic function and associated RV systolic dysfunction, or pulmonary hypertension

    • Mitral Doppler inflow patterns also help in the diagnosis of concomitant diastolic dysfunction

    • Color flow Doppler can reveal tricuspid or mitral regurgitation, and continuous Doppler can estimate pulmonary artery pressures

    • Intracavitary thrombosis is occasionally seen

  • Exercise or pharmacologic stress myocardial perfusion imaging may uncover underlying coronary disease

  • Radionuclide ventriculography

    • Provides a noninvasive measure of the EF and both RV and LV wall motion

    • However, its use has been supplanted by cardiac MRI in most institutions

  • Cardiac catheterization

    • Seldom of specific value unless myocardial ischemia is ...

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