Dilated cardiomyopathy
Updates to Article Attributes
Dilated cardiomyopathy (DCM) is defined as left ventricular chamber dilation with decreased systolic function (FEVG <40%) in the absence of coronary artery disease or conditions whichthat impose a chronic pressure overload. There may also be right ventricular dysfunction. Causes are related to intrinsic myocardial damage.
Pathology
The ventricles are dilated and poorly contractile with normal or reduced wall thickness. The atria may also have a similar appearance and function.
Aetiology
Although a variety of aetiologies can result in dilated cardiomyopathy which are listed below. Some are classified as separate entities. (See WHO 1995 classification of cardiomyopathies)
ischaemic (coronary artery disease) - ischaemic cardiomyopathy- infectious (myocarditis: virus, bacteria)
- infiltrative disease (sarcoid, amyloid)
- metabolic (uraemia, hypocalcemia, hypophosphataemia, thyrotoxicosis, beriberi)
- toxic (alcohol, cocaine)
- chemotherapy (doxorubicin)
- others (peripartum, muscular dystrophies)
- autoimmune cross-reactivity (e.g. late-onset cardiomyopathy in Chagas disease)
- idiopathic: idiopathic dilated cardiomyopathy
- familial: familial dilated cardiomyopathy 7
Associations
Radiographic features
Plain radiograph
Chest radiographs commonly show an enlarged left ventricle and atria with pulmonary oedema. Associated pleural effusions may also be seen.
Ultrasound: echocardiography
The degree of left ventricular dilatation is highly variable and depends on the stage of disease and severity of left ventricular dysfunction.
- global chamber dilation with increased sphericity
- elevation in left ventricular mass and volumes
- may be inferred by a measured elevation in LV end-diastolic internal diameter
- the LVIDd upper limit of normal is 5.9 cm in males and 5.3 cm in females
- wall thickness may be normal (between 0.6 cm and 1.2 cm) or reduced
- may be inferred by a measured elevation in LV end-diastolic internal diameter
- the ratio between the long and short axes of the left ventricle may decrease to 1 in severe cases
- a normal LV has an LAX/SAX ratio of around 1.5
- consequent mitral annular dilation and failure of coaptation leading to mitral regurgitation is common
- elevation in left ventricular mass and volumes
- perturbation of systolic function
- left ventricular ejection fraction will decrease, although stroke volume may be initially preserved
-
diastolic dysfunction
- with progressively higher E/e' ratio (correlates with left atrial pressure) as filling pressures elevate
Cardiac MRI
In idiopathic dilated cardiomyopathy, the left heart is markedly dilated and thinned, and mid-wall enhancement, especially in the septum, is present in more than 50% of patients 4.
Late enhancement MR images may demonstrate areas of fibrosis within the myocardium, characteristically in the mid- or subepicardial myocardium, allowing differentiation from ischaemic cardiomyopathy 6.
Differential diagnosis
Conditions mimicking the clinical presentation or imaging appearance of dilated cardiomyopathy include:
- ischaemic cardiomyopathy/left ventricular aneurysm
- non compaction cardiomyopathy
- left ventricular dilatation due to valvular heart disease
On plain radiographs consider:
- large pericardial effusion
-<p><strong>Dilated cardiomyopathy (DCM)</strong> is defined as <a href="/articles/left-ventricle">left ventricular</a> chamber dilation with decreased systolic function (FEVG <40%) in the absence of coronary artery disease or conditions which impose a chronic pressure overload. There may also be <a href="/articles/right-ventricle">right ventricular</a> dysfunction. Causes are related to intrinsic myocardial damage.</p><h4>Pathology</h4><p>The ventricles are dilated and poorly contractile with normal or reduced wall thickness. The atria may also have a similar appearance and function.</p><h5>Aetiology</h5><p>Although a variety of aetiologies can result in dilated cardiomyopathy which are listed below. Some are classified as separate entities. (See <a href="/articles/cardiomyopathy-whoisfc-1995-classification">WHO 1995 classification of cardiomyopathies</a>) </p><ul>-<li>ischaemic (coronary artery disease) - ischaemic cardiomyopathy</li>- +<p><strong>Dilated cardiomyopathy (DCM)</strong> is defined as <a href="/articles/left-ventricle">left ventricular</a> chamber dilation with decreased systolic function (FEVG <40%) in the absence of coronary artery disease or conditions that impose a chronic pressure overload. There may also be <a href="/articles/right-ventricle">right ventricular</a> dysfunction. Causes are related to intrinsic myocardial damage.</p><h4>Pathology</h4><p>The ventricles are dilated and poorly contractile with normal or reduced wall thickness. The atria may also have a similar appearance and function.</p><h5>Aetiology</h5><p>Although a variety of aetiologies can result in dilated cardiomyopathy which are listed below. Some are classified as separate entities. (See <a href="/articles/cardiomyopathy-whoisfc-1995-classification">WHO 1995 classification of cardiomyopathies</a>) </p><ul>
-<a href="/articles/intra-cardiac-clot">intra-cardiac </a><a href="/articles/intracardiac-thrombi">thrombus</a>- +<a href="/articles/intra-cardiac-clot">intra-cardiac </a><a href="/articles/intracardiac-thrombus-1">thrombus</a>
-<li>a normal LV has an LAX/SAX ratio around 1.5</li>- +<li>a normal LV has an LAX/SAX ratio of around 1.5</li>
-</ul><h5>Cardiac MRI</h5><p>In idiopathic dilated cardiomyopathy, the left heart is markedly dilated and thinned, and mid-wall enhancement, especially in the septum, is present in more than 50% of patients <sup>4</sup>.</p><p><a title="Late enhancement" href="/articles/late-gadolinium-enhancement-lge">Late enhancement</a> MR images may demonstrate areas of fibrosis within the myocardium, characteristically in the mid- or subepicardial myocardium, allowing differentiation from ischaemic cardiomyopathy<sup> 6</sup>.</p><h4>Differential diagnosis</h4><p>On plain radiographs consider:</p><ul><li>large <a href="/articles/pericardial-effusions">pericardial effusion</a>- +</ul><h5>Cardiac MRI</h5><p>In idiopathic dilated cardiomyopathy, the left heart is markedly dilated and thinned, and mid-wall enhancement, especially in the septum, is present in more than 50% of patients <sup>4</sup>.</p><p><a href="/articles/late-gadolinium-enhancement-2">Late enhancement</a> MR images may demonstrate areas of fibrosis within the myocardium, characteristically in the mid- or subepicardial myocardium, allowing differentiation from ischaemic cardiomyopathy<sup> 6</sup>.</p><h4>Differential diagnosis</h4><p>Conditions mimicking the clinical presentation or imaging appearance of dilated cardiomyopathy include:</p><ul>
- +<li>ischaemic cardiomyopathy/<a href="/articles/left-ventricular-aneurysm">left ventricular aneurysm</a>
- +</li>
- +<li><a href="/articles/non-compaction-of-the-left-ventricle-1">non compaction cardiomyopathy</a></li>
- +<li>left ventricular dilatation due to <a title="Valvular heart disease" href="/articles/valvular-heart-disease">valvular heart disease</a>
- +</li>
- +</ul><p>On plain radiographs consider:</p><ul><li>large <a href="/articles/pericardial-effusions">pericardial effusion</a>
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