creation date: 2025-10-20 16:25
tags: Pathologies
Dilated Cardiomyopathy
Background
Definitions
Dilated cardiomyopathy (DCM) is a disease of the the heart muscles. It is characterized by the dilation and enlargement of one or both ventricles and impaired contractility and thus ejection fraction. DCM is generally progressive and leads to heart failure.
DCM can be primary or idiopathic or a secondary to another condition.
Etiology & Risk Factors
The most common cause is idiopathic which likely involve familial or genetic predisposition with mutations affecting desmin (cytoskeletal), lamin C (nuclear membrane), or myosin (contractile proteins).
Secondary causes include:
- Infective myocarditis (eg. viral, Chagas disease, Lyme disease)
- Ischemic disease
- Hypertension
- Medication-induced (eg. anthracyclines)
- Alcohol abuse
- HIV
- Peripartum cardiomyopathy
- Infiltrative disease
It should be noted that ischemic cardiomyopathy and Takotsubo cardiomyopathy is occasionally described as a cause of DCM but are considered their own disease entities and discussed separately.
Pathogenesis
The exact mechanism that results in dilation depends on the etiology. In idiopathic etiology, the ventricle enlargement occurs due to abnormalities in the genes that encode for normal cardiomyocyte function and structure.
In secondary DCM, enlargement may occur secondary to left ventricular failure or to a primary cardiomyopathic process.
In either case, the progressive dilatation of the ventricles is associated with systolic and diastolic dysfunction causing increased end-systolic and end-diastolic volumes and thus reduced ejection fraction. Additionally, enlargement of the ventricles results in tricuspid and mitral valve insufficiency which further reduce ejection fraction.
Compensatory mechanisms results in myocardial remodelling which worsens injury.
Clinical Presentation
Findings are consistent with congestive heart failure.
Diagnosis
Criteria
Diagnosis is made with echocardiography, providing assessment of:
- Ventricular size
- Ventricular function
- Valvular abnormalities
- Mural thrombus
Work-up
Workup should evaluate for secondary causes of DCM.
Laboratory studies
- CBC (for anemia)
- Thyroid function tests
- HIV serology
- Electrolytes
- Iron studies (for hemochromatosis)
- Urine toxicology
Cardiac workup
- BNP (can rule out HF and used for prognosis)
- ECG
- Chest x-ray (cardiomegaly, signs of venous congestion)
- Coronary angiography (if CAD suspected)
- Echocardiography (diagnosis)
Differential
Other cardiomyopathies include:
- Hypertrophic cardiomyopathy
- Restrictive cardiomyopathy
These are generally distinguishable by echocardiography.
Other conditions include:
- Cardiac tamponade
- Acute pericarditis
Red Flags / Complications
Complications include:
- Congestive heart failure
- Cerebrovascular accident
- Valvular heart disease
- Abnormal cardiac rhythms
- Sudden cardiac death
- Thromboembolism
Management
For patients who are incidentally found to have dilated myocardium or have a family history, pre-emptive use of heart failure medications may be indicated. The mainstay of management, however, consist of managing risk factors and comorbidities.
Treatment for patients with heart failure is discussed separately.