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Dilated cardiomyopathy (DCM) is the occurrence of ventricular dilatation and systolic dysfunction despite normal filling pressures, in the absence of coronary artery disease, abnormal loading pressures (e.g., valvular heart disease, hypertension), or congenital heart disease. It is the most common type of cardiomyopathy. Although most cases are idiopathic or inherited, DCM can also be caused by a number of conditions (e.g., endocrine disorders, autoimmune disease) and infections (e.g., Coxsackie B virus, Chagas disease) and by the use of certain substances (e.g., heavy drinking, cocaine). In DCM, decreased left ventricular contractility leads to left heart failure and eventually right heart failure with decreased ventricular output. Isolated dilation and subsequent decrease in right ventricular contractility is rare. Diagnosis is confirmed with echocardiography. Studies to evaluate the underlying etiology should be guided by clinical suspicion and include laboratory studies, genetic testing, advanced cardiac imaging, and, rarely, endomyocardial biopsy. Management involves treatment of the underlying condition and associated complications, e.g., congestive heart failure and arrhythmias. Severe or refractory disease may be managed with device implantation or cardiac transplantation.
- Incidence: ∼ 6/100,000 per year (most common cardiomyopathy) 
- Sex: ♂ > ♀ (∼ 1.5:1) 
- Age at presentation: most commonly between 30 and 40 years of age, but can occur at any age 
- Ethnicity: more common in individuals of African descent 
Epidemiological data refers to the US, unless otherwise specified.
- Idiopathic 
- Familial, due to mutations in genes that encode components for sarcomeres and desmosomes, such as: ; 
Secondary causes 
- Substance use
- Cardiotoxic medications, e.g., anthracyclines (such as doxorubicin and daunorubicin), AZT, trastuzumab
- Infection (infectious myocarditis)
- Infiltrative and autoimmune disorders
- Peripartum cardiomyopathy (can occur in the last trimester or up to 6 months postpartum)
- Chronic tachycardia, e.g., atrial fibrillation
- Radiation 
- Endocrinopathies, e.g., pheochromocytoma, acromegaly, hyperthyroidism
- Neuromuscular diseases, e.g., myotonic dystrophy, Duchenne muscular dystrophy
- Nutritional deficiencies, e.g., thiamine (wet beriberi), selenium, carnitine
Volume and pressure overload secondary to conditions such as hypertension and valvular heart disease can cause dilation of the myocardium; however, these are not considered forms of DCM, as filling pressures are abnormal. 
- Causative factors decrease the contractility of the myocardium → activation of compensatory mechanisms () to maintain → ↑ end-diastolic volume (preload) → → eccentric hypertrophy (sarcomeres added in series) and dilation of the ventricle ; → reduced myocardial contractility → systolic dysfunction and ↓ ejection fraction → heart failure
- Decreased LV contractility due to dilation leads to and eventually (see “Pathophysiology of congestive heart failure”).
- Gradual development of
- Some patients may present with .
Physical examination 
- Systolic murmur secondary to mitral valve regurgitation; or tricuspid valve regurgitation 
- S3 gallop
- Displacement of the apex beat
- Jugular venous distention
- Bilateral rales
- Peripheral edema
DCM is typically diagnosed during the workup for associated cardiac conditions (e.g., heart failure) or through screening of family members of patients with known or suspected familial DCM. 
- Confirm the diagnosis on echocardiography.
- Rule out ischemic cardiomyopathy in patients with features of ischemic heart disease: See “Diagnostics for CAD.”
- Assess for complications, e.g., heart failure, arrhythmias. 
- Evaluate for the underlying etiology.
- Underlying etiology remains unclear:
- Idiopathic DCM: Refer for genetic counseling and testing to evaluate for a possible genetic etiology.
- To confirm the diagnosis of suspected DCM
- To screen first-degree relatives of patients with familial DCM 
- Characteristic findings
Initial diagnostic workup
Laboratory studies 
- CBC with differential 
- Basic metabolic panel
- Liver chemistries
- HIV testing
- Ferritin, transferrin saturation
- : in patients with concomitant heart failure 
- Additional studies as needed for the underlying etiology as guided by clinical evaluation, such as:
- Indications: to assess for complications and the underlying etiology 
- Possible findings include:
- To assess for complications (e.g., AV block)
- To rule out
- Possible findings include 
- Indications 
- Possible findings include: 
Genetic testing 
- Patients with suspected familial or idiopathic DCM
- Family members of patients with DCM and an associated genetic mutation
- Consider in patients with DCM and any of the following: 
Advanced studies 
- Indication: suspected underlying etiology that requires specific management (e.g., amyloidosis) and cannot be confirmed by other diagnostic methods
- Findings vary based on the underlying etiology.
- Treat the underlying cause of DCM: e.g., ; manage endocrine abnormalities, encourage abstinence from alcohol.
- Avoid cardiotoxic agents, if possible.
- , if present.
- In severe or refractory disease, consider:
Management of the underlying etiology 
|Management of underlying disease in dilated cardiomyopathy |
|Substance use disorder|
|Chemotherapy-related cardiomyopathy|| |
|Peripartum cardiomyopathy|| |
Management of complications
- Congestive heart failure 
Arrhythmias: Management does not differ from standard best practice. 
- See “ .”
- See “ .”
- Secondary mitral regurgitation: Consider mitral valve surgery. 
- Thromboembolic events: anticoagulation 
Severe or refractory DCM 
- Consider device implantation in selected patients with persistently low LVEF on optimized medical therapy.
- If symptomatic with LVEF ≤ 35%: AICD (to prevent sudden cardiac death due to ventricular fibrillation)
- If symptomatic with LVEF ≤ 35%, sinus rhythm, and QRS > 150 ms: cardiac resynchronization therapy (to improve contractility)
- See “Invasive interventions” in “Treatment of heart failure” for additional eligibility criteria.
- DCM refractory to medical therapy and device implantation: Consider heart cardiac transplantation.
Left ventricular assist devices can be considered as:
- A bridge to transplant
- An alternative therapy for refractory DCM in patients who are ineligible for transplant
DCM is the leading indication for heart transplantation. 
Special patient groups
Dilated cardiomyopathy in pregnancy 
- Generally, pregnancy is not recommended for patients with DCM and LVEF < 30% and/or III or IV heart failure. 
- Consider exercise stress testing prior to pregnancy.
- For patients on ACEIs or ARBs, discontinue and assess cardiac function.
- In familial DCM, offer genetic counseling to discuss potential transmission.
- Be aware of .
- Consult specialists (e.g., cardiology, obstetrics, maternal-fetal specialists) for the management of DCM.
- Monitor for .