Dilated cardiomyopathy

Definition

‍Regardless of the cause of the disease, dilated cardiomyopathy is best described as a progressive ventricular wall thinning and dilation accompanied with gradual functional impairment.

Etiology (Image 1)

Pathophysiology

The initial stimuli that induce DCM are diverse, but they all lead to increased wall stress which in combination with neurohumoral activation causes maladaptive changes in myocardial structure.

The initial stimuli together with neurohumoral and biochemical changes create a vicious cycle which progressively leads to systolic  dysfunction and heart failure (Image 2).

Camm, J. A., Lüscher, T. F., & Serruys, P. (2020). The ESC Textbook of Cardiovascular Medicine (3rd ed.). Wiley-Blackwell.

Epidemiology

The estimated prevalence of dilated cardiomyopathy is 1:2500.

Clinical manifestation

Most often, DCM patients are less symptomatic and present with higher exercise tolerance when compared with other cardiomyopathies.

Classic symptoms include paroxysmal nocturnal dyspnea, orthopnea, leg swelling, and shortness of breath.

‍Nonspecific symptoms of fatigue, malaise, and weakness also can be present.

More severe cases can present with thromboembolic complications, conduction disturbances, arrhythmias or even sudden cardiac death.

Physical examination findings include crackles in the lung fields, elevated jugular venous pressures, peripheral edema, and an S3 gallop.

Tricuspid or mitral regurgitation murmurs are not uncommon as a result of ventricular enlargement and annular dilation.

Neck examination may reveal jugular venous distension, A-wave, large V waves, and positive hepatojugular reflux.

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Echocardiography findings

Echocardiography is the first-line imaging test in the assessment of patients with DCM. It provides information for diagnosis, risk stratification and guiding treatment, but also plays a key role in screening family members.

1. Assessment of LV dilatation

The hallmark of the disease is a global LV dilation. With the progression of the disease, the LV shows a change in its geometry becoming more spherical, with increased short axis/long axis ratio (sphericity index). Increased sphericity index is a common echocardiographic feature.

Internal dimensions of the left ventricle are measured at end-diastole, when the LV is largest (LVEDD) and at end-systole (LVESD).

LV dilatation can also be assessed via left ventricular volumes obtained using 2D imaging from A4C and A2C views and the biplane Simpson’s method.

Make sure that the LV is not foreshortened and the inner-edge of the LV is traced carefully.

Volumes are then reported after indexing to BSA - end-diastolic volume (EDVi) and end-systolic volume (ESVi).

Image 3 Normal values of LV size and function

Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the American Society of Echocardiography and the European Association of, Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging. 2016 Apr;17(4):412. doi: 10.1093/ehjci/jew041. Epub 2016 Mar 15. Erratum for: Eur Heart J Cardiovasc Imaging. 2015 Mar;16(3):233-70. PMID: 26983884.

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2. Assessment of LV systolic function

Main features are decreased ejection fraction with cut off values < 45% and impaired global contractility of myocardium.

Easiest way to measure ejection fraction is by the Simpson biplane method derived from a 2D image of the LV in orthogonal views.

Other method is described in a figure below (Image 4).

3. Assessment of LV motion abnormalities

In DCM the common finding is diffuse hypokinesis of myocardium.

4. Assessment of LV wall thickness

In DCM the LV wall thickness can be normal, increased or eccentric hypertrophy can be found.

Video 1 Dilated cardiomyopathy in a patient with history of chemotherapy for Ewing sarcoma in childhood, A4C view - a severely dilated and spherical left ventricle , severely reduced ejection fraction (20-25%) and diffuse hypokinesis. LVEDD 78mm, LVESD 41mm, EDVi 138 ml/m2, ESVi 105 ml/m2.

Image 5 Dilated cardiomyopathy,  measurement of LV volumes in A4C and A2C views - the endocardial border of LV is traced to measure end-diastolic and end-systolic volumes. Ejection fraction (EF) is then calculated.

Video 2 Dilated cardiomyopathy in a patient with history of chemotherapy for Ewing sarcoma in childhood, PLAX view  - note the spherical shape and severe dilation of the left ventricle.

Image ‍6 Dilated cardiomyopathy in a patient with history of chemotherapy for Ewing sarcoma in childhood, Global longitudinal strain assessment (GLS) 

Video 3 Dilated cardiomyopathy, A4C view -  a severely dilated LV with reduced EF to 25% measured by Simpson’s biplane method thanks to diffuse hypokinesis.

Image 7 Dilated cardiomyopathy, Simpson’s biplane method  - LV volume measured in A4C and A2C views, the LV is severely dilated (EDVi 125.0 ml, ESVi 94.0 ml)

Video 4 Dilated cardiomyopathy, PLAX view with colour Doppler - note the spherical shape of the dilated LV. Colour Doppler shows holosystolic regurgitant jet of moderate secondary mitral regurgitation caused by annular dilation and remodellation, often associated with dilated CMP.

Video 5 Dilated cardiomyopathy, A4C view - patient with a family history of dilated CMP. The LV is severely dilated with estimated EF 20%, severe diffuse hypokinesis - note that the walls are barely moving. The right ventricle is also dilated and has worsened systolic function. Both atria are severely dilated, ICD electrode in RA.

Video 6 Dilated cardiomyopathy, PSAX view - patient with a family history of dilated CMP, eccentric hypertrophy of the severely dilated LV and dilated RV.

Image 8 GLS assessment in the above patient with dilated cardiomyopathy - note the markedly reduced GLS (light red to blue color on the Bull’s eye) diffusely across the LV.

Video 7 Severe case of dilated cardiomyopathy, A4C view with colour Doppler - all cardiac chambers are severely dilated. Heavily dilated and spherical LV (LVEDD 97mm) with EF under 20%. Severe (4/4) secondary mitral regurgitation - large regurgitant jet in colour Doppler is seen along the lateral wall of LA. Massive dilation of LA (LAVi 111 cm3/m2)

Image 9 Severe case of dilated cardiomyopathy,  end-systolic measurement of LV diameters - LVEDD 97mm, 3mm pericardial separation along the lateral wall.

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5. Assessment of LV diastolic function

Diastolic dysfunction is frequent in DCM, reflecting structural LV wall pathology (particularly fibrosis), and chamber remodeling.

Both abnormal relaxation and increased LV stiffness are present in the disease, with resulting increased LV filling pressure. 

Diastolic dysfunction of the left ventricle can be assessed with several echocardiographic parameters. In particular, a “restrictive LV filling pattern” characterized by a short deceleration time of E (<150 ms) and an increased E/A ratio (>2) at transmitral inflow pulsed Doppler tracing.

On the other hand, an increased E/E′ ratio (i.e., early diastolic mitral filling E/early diastolic mitral annular velocity E′ at TDI) correlates with diastolic dysfunction and increased LV filling pressure.

Image 10 Diastolic dysfunction assessment by echocardiography

Ghanem, & Ghanem, Rowa & Al- Selevany, Baybeen & Habeeb, Mothafar & Frcp-Glasg,. (2016). BODY MASS INDEX AND BLOOD PRESSURE INFLUENCES ON LEFT VENTRICULAR DIASTOLIC FUNCTION, MASS AND GEOMETRY. 5. 10.20959/wjpps20166-7090. 

Image 11 PW Doppler, transmitral inflow in dilated cardiomyopathy - restrictive filling pattern with dominant E wave and very small A wave. E/A ratio is 9,88 and the deceleration of E wave (MV DecT) is only 114 ms.

Image 12 Septal (left) and lateral wall (right) Tissue Doppler Imaging (TDI) - septal e’ 6cm/s and lateral e’ is 11 cm/s. The E/e’ is 11,5.

Image 13 Pseudonormal filling (Grade II diastolic dysfunction) in dilated cardiomyopathy, PW Doppler mitral inflow - E/A 1,29

6. Assessment of LV dyssynchrony

Echocardiography provides a multiparametric qualitative and quantitative approach for assessment of LV mechanical dyssynchrony.

The “apical rocking” motion of the LV is qualitative diagnostic feature, which should be confirmed by other indices, as “septal flash”, which is septal to posterior wall motion delay at M-mode, and TDI-derived indices (intervals from QRS to peak systolic velocities of wall motion of different LV segments, assessing the delay between opposite LV walls).

7. Assessment of LA dilatation

In DCM LA dilatation is associated with diastolic dysfunction, mitral valve regurgitation and atrial fibrillation.

The End-systolic LA volume index (LAVi) values in accordance with LA dilation are summed up below (Image 14).

Image 15 Dilated cardiomyopathy, assessment of dilated LA in A4C view - length 61 mm, LA area 26 cm2

Image 16 Dilated cardiomyopathy, assessment of dilated LA in A2C view - length 60 mm, LA area 29 cm2 The calculated LA volume index (LAVi) is 57.7 cm3 /m2

8. Assessment of RV dilatation and systolic dysfunction

RV dilation and systolic dysfunction are frequent in DCM and can represent biventricular involvement of the disease or they are secondary to RV pressure overload due to left-side disease.  The presence of RV dilation is usually assessed with 2D echocardiography from standard echocardiographic views. RV systolic function is estimated with various parameters, as fractional area change (FAC) or tricuspid annular peak systolic excursion (TAPSE).

Image 17 Dilated right ventricle in DCMP, traced in A4C view - RVD1 45 mm, RVD2 34 mm, RVD3 92 mm, calculated FAC 22%

Video 8 Dilated right ventricle with severe tricuspid regurgitation, A4C view with colour Doppler

Image 18 Dilated right ventricle with severe systolic dysfunction in DCMP, dimension measured in A4C view - the FAC is calculated to 20% and TAPSE is 14 mm.

Image 19 Tricuspid Annular Plane Systolic Excursion (TAPSE), reduced excursion in dilated cardiomyopathy (TAPSE 14mm)

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Cardiac magnetic resonance

CMR is useful and provides:

• Differential diagnosis between ischemic and non-ischemic dilated CMP.
• Differential diagnosis in non-ischemic dilated CMP.
• Accurate assessment of ventricular volumes, wall thickness, and contractile function, as well as tissue characterization (pretreatment and follow-up).
• Provide prognostic information - late gadolonium enhancement.

Management

Treatment of dilated cardiomyopathy is essentially the same as treatment of chronic heart failure (CHF).

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References

1. PINAMONTI, Bruno, Elena ABATE a Antonio DE LUCA et al. Role of Cardiac Imaging: Echocardiography [online]. May 18, 2019, Chapter 7 [cit. 2021-8-14]. Dostupné z: https://www.ncbi.nlm.nih.gov/books/NBK553855/

2. Mathew T, Williams L, Navaratnam G, Rana B, Wheeler R, Collins K, Harkness A, Jones R, Knight D, O'Gallagher K, Oxborough D, Ring L, Sandoval J, Stout M, Sharma V, Steeds RP; British Society of Echocardiography Education Committee. Diagnosis and assessment of dilated cardiomyopathy: a guideline protocol from the British Society of Echocardiography. Echo Res Pract. 2017 Jun;4(2):G1-G13. doi: 10.1530/ERP-16-0037. PMID: 28592613; PMCID: PMC5574280.

3. Ghanem, & Ghanem, Rowa & Al- Selevany, Baybeen & Habeeb, Mothafar & Frcp-Glasg,. (2016). BODY MASS INDEX AND BLOOD PRESSURE INFLUENCES ON LEFT VENTRICULAR DIASTOLIC FUNCTION, MASS AND GEOMETRY. 5. 10.20959/wjpps20166-7090. 

4. Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the American Society of Echocardiography and the European Association of, Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging. 2016 Apr;17(4):412. doi: 10.1093/ehjci/jew041. Epub 2016 Mar 15. Erratum for: Eur Heart J Cardiovasc Imaging. 2015 Mar;16(3):233-70. PMID: 26983884.

5. Camm, J. A., Lüscher, T. F., & Serruys, P. (2020). The ESC Textbook of Cardiovascular Medicine (3rd ed.). Wiley-Blackwell.

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