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Cardiomyopathy

DiseaseUpdated: 2023-01-26

Summary

Cardiomyopathies are diseases of the muscle tissue of the heart. Types of cardiomyopathies include dilated (most common), hypertrophic, restrictive, and arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) primarily affects the right ventricle and is characterized by fibrofatty replacement of myocardium, which causes myocardial thinning and subsequent ventricular dilation. Although the hallmark finding is arrhythmia, symptoms are highly variable. Because management depends greatly on individual factors, such as the extent of the disease, there is no single best course of treatment. All patients should avoid strenuous exercise.

Arrhythmia-induced cardiomyopathy is a very rare type of cardiomyopathy. It is caused by long-standing arrhythmia and typically affects the left ventricle. Features include palpitations, syncope, and signs of arrhythmia on ECG. Progression to left heart failure is possible in severe cases. Treatment involves antiarrhythmics such as beta blockers for rhythmic control.

“Dilated cardiomyopathy”, “Hypertrophic cardiomyopathy,” “Restrictive cardiomyopathy,” and “Peripartum cardiomyopathy” are described in their respective articles in more detail.

Overview of major types of cardiomyopathy

Differential diagnosis of major cardiomyopathies
Types Dilated cardiomyopathy Hypertrophic cardiomyopathy Restrictive cardiomyopathy
Etiology
  • Mostly idiopathic
  • Genetic predisposition (TTN gene mutation)
  • Ischemic heart disease
  • Infectious diseases
    • Coxsackie B virus
    • Chagas disease
    • HIV
  • Systemic disorders
    • Sarcoidosis
    • Hemochromatosis
    • Thiamine deficiency (wet beriberi)
  • Toxic substances
    • Cocaine
    • Alcohol
    • Medication (e.g., doxorubicin)
  • Peripartum cardiomyopathy
  • Inherited (autosomal dominant) mutation of:
    • Myosin binding protein C
    • β-Myosin heavy chain
  • Mostly idiopathic
  • Systemic disorders
    • Amyloidosis
    • Sarcoidosis
    • Hemochromatosis
    • Systemic sclerosis
  • Heart disease
    • Loffler endocarditis
    • Endocardial fibroelastosis
  • Post-radiation fibrosis
Pathophysiology
  • Eccentric hypertrophy of the left ventricle → ↓ ventricular contractility → ↓ LVEF
  • Concentric hypertrophy of the left ventricle (including the interventricular septum) → ↓ ventricular relaxation → ↓ diastolic filling and systolic output → ↓ myocardial and peripheral perfusion
  • Obstructive type (HOCM): left ventricular outflow tract (LVOT) obstruction and mitral regurgitation due to systolic anterior movement (SAM) of the mitral valve [1]
  • Proliferation of connective tissue →
    • ↓ Elasticity of cardiac tissue
    • Atrial enlargement and severe diastolic dysfunction
Distinctive clinical features
  • Signs of left heart failure and right heart failure
  • S3 gallop
  • Systolic murmur
  • Frequently asymptomatic
  • Signs of left heart failure (dyspnea, syncope, dizziness)
  • Arrhythmias
  • S4 gallop
  • Possible holosystolic murmur from mitral regurgitation
  • Sudden death
  • Signs of left heart failure and right heart failure
Echocardiography LV cavity size
  • Significantly increased
  • Decreased
  • Decreased
EF
  • Significantly decreased
  • Normal
  • Normal or increased
Wall thickness
  • Normal or decreased
  • Significantly increased
  • Usually increased
Additional findings
  • Left or biventricular dilation (with or without atrial dilation)
  • Wall motion abnormalities
  • Systolic dysfunction
  • Normal diastolic function
  • Outflow tract obstruction (SAM, interventricular septum hypertrophy)
  • Reduced diastolic filling
  • Dilated atria, nondilated ventricles
  • Reduced diastolic filling
Other characteristics
  • Most common cardiomyopathy
  • Second most common cardiomyopathy
  • Most common cause of sudden heart failure in athletes and teenagers
  • Poor prognosis without heart transplant

Overview of cardiomyopathies
Overview of cardiomyopathies
© AMBOSS
Endocardial fibroelastosis
Endocardial fibroelastosis

Autopsy specimen of a heart

The opened left atrium and ventricle can be seen. There is substantial endocardial fibroelastosis, which manifests as increased whiteness of the endocardium (star).


Source: “Fig 2A, In: Barth syndrome” by Clarke SL, Bowron A, Gonzalez IL et al., BMC Orphanet Journal of Rare Diseases, licensed under CC BY 2.0. Modifications: image cropped & removal of the letter A.
Hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy

Hypertrophy of the myocardium results in reduced diastolic compliance and filling of the left ventricle (sometimes also of the right ventricle). Hypertrophic cardiomyopathy can occur with or without left ventricular outflow tract obstruction. Hypertrophic obstructive cardiomyopathy (HOCM) occurs when hypertrophy of the interventricular septum and systolic anterior movement (SAM) of the mitral valve leaflet results in the left ventricular outflow tract (LVOT) obstruction.


© AMBOSS
Dilated cardiomyopathy
Dilated cardiomyopathy

Transthoracic echocardiogram (upper image: apical four-chamber view; lower left image: end-diastolic apical four-chamber view; lower right image: end-systolic apical four-chamber view)

Upper image: Compared to normal findings (green dashed outline), the left ventricular cavity size (red overlay) is significantly increased (green arrows); ventricular wall thickness is normal. The left atrium is also dilated. An implantable cardioverter defibrillator (ICD) lead is visible in the right ventricle.

Lower images (calculations using biplane Simpson method): Both end-diastolic volume (EDV; left image) and end-systolic volume (ESV; right image) are markedly increased, and the ejection fraction (EF) is markedly below normal at 21% (normal value is ∼ 55%).

This combination of findings is typical of dilated cardiomyopathy.

LV: left ventricle; MV: mitral valve; LA: left atrium; RA: right atrium; TV: tricuspid valve; RV: right ventricle


Source: “Fig. 7.2, and 7.3, in: Role of Cardiac Imaging: Echocardiography” by Pinamonti B, Abate E, De Luca A, Finocchiaro G, Korcova R, Dilated Cardiomyopathy, licensed under CC BY 4.0. Modifications: - two images were combined - added illustration. The supplementary image with overlays of relevant areas was adapted from the image mentioned above (© AMBOSS).
Hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy

Transthoracic echocardiogram (apical three-chamber view)

The walls of the left ventricle are asymmetrically hypertrophied. Compared to normal findings (green dashed outline), the interventricular septum (red overlay) is markedly thickened (green arrows). The lateral wall is also thickened, but not to the same extent as the interventricular septum.

These findings are suggestive of hypertrophic cardiomyopathy. To assess for left ventricular outflow tract (LVOT) obstruction, the LVOT pressure gradient during systole should be measured.

LW: lateral wall; LV: left ventricle; IVS: interventricular septum; MV: mitral valve; AV: aortic valve; LA: left atrium


Source: “Fig. 1, in: The role of echocardiography for diagnosis and prognostic stratification in hypertrophic cardiomyopathy” by Mandeş L, Roşca M, Ciupercă D, Popescu BA, Journal of Echocardiography, licensed under CC BY 4.0. Modifications: - cropped image - removed letter - added illustration. The supplementary image with overlays of relevant areas was adapted from the image mentioned above (© AMBOSS).
Restrictive cardiomyopathy
Restrictive cardiomyopathy

Transthoracic echocardiogram (upper image: apical four-chamber view in systole; lower image: apical four-chamber view, pulse wave Doppler of left ventricular inflow)

Upper image: Compared to normal findings (green dashed outlines), both atria (red overlay) are significantly enlarged (green arrows). Left ventricular volume and wall thickness are normal, and left ventricular ejection fraction is also normal (62%; not shown on image).

Lower image: The E/A ratio is > 1.5 (the velocity of the E wave of early diastolic left ventricular filling is ∼ 1 m/s and that of the A wave of late diastolic left ventricular filling is ∼ 0.4 m/s, resulting in a ratio of ∼ 2.5), indicating a restrictive diastolic filling pattern and severe diastolic dysfunction.

The combination of normal ventricular volume, wall thickness, and ejection fraction with atrial enlargement and diastolic dysfunction is consistent with restrictive cardiomyopathy. An important differential is constrictive pericarditis.

RV: right ventricle; LV: left ventricle; TV: tricuspid valve; MV: mitral valve; RA: right atrium; LA: left atrium; E: E wave; A: A wave


Source: “Fig. 1(b) and 1(c), in: Restrictive Cardiomyopathies: The Importance of Noninvasive Cardiac Imaging Modalities in Diagnosis and Treatment—A Systematic Review” by Rammos A, Meladinis V, Vovas G, Patsouras D, Hindawi, licensed under CC BY 4.0. Modifications: - two images combined - added illustration. The supplementary image with overlays of relevant areas was adapted from the image mentioned above (© AMBOSS).

Arrhythmogenic right ventricular cardiomyopathy (ARVC)

Epidemiology

  • Most common in young adults (mean age at diagnosis: ∼ 30 years) [2]
  • Prevalence: 1:1,000–2,000 [3]

Etiology

  • Mutations of various genes (e.g., JUP gene)
  • Autosomal recessive or autosomal dominant inheritance [3][4]

Pathophysiology

  • Right ventricular myocardial cell death (due to myocyte apoptosis, inflammation, and fatty/fibrotic tissue replacement) → thinning of the right ventricular wall → dilation of the ventricle → ventricular arrhythmia and dysfunction [2]
  • The left ventricle can also be affected, but consequences are usually less severe.

Clinical features

  • Highly variable
  • Many patients remain asymptomatic.
  • Angina pectoris
  • Dyspnea
  • Peripheral edema, ascites, hepatic and splenic congestion
  • Palpitations, syncope, possibly sudden cardiac death (particularly during or after exercise)

Diagnostics [2][3][5]

Approach

ARVC is diagnosed based on the AHA criteria which include the following features:

  1. Dysfunction and structural abnormalities of RV (can be revealed by echocardiography, MRI, or RV angiography)
  2. Histological characteristics (require myocardial biopsy)
  3. Abnormal repolarization (diagnosed with ECG)
  4. Depolarization/conduction abnormalities (diagnosed with ECG)
  5. Arrhythmias (diagnosed with ECG)
  6. Family history (confirmation of ARVC in a relative either by criteria, pathological examination in surgery or autopsy, or by genetic testing)

Findings

  • ECG
    • Repolarization disturbances in the right precordial leads (V1-3)
      • Possibly epsilon wave (at the end of a widened QRS complex)
      • Highly specific for ARVC but only occurs in ∼ ⅓ of patients
    • Increased QRS duration
    • Ventricular tachycardia
    • Ventricular extrasystoles
  • Echocardiography and cardiac MRI
    • RV enlargement
    • RV wall motion abnormalities
    • ↓ RV EF
    • Localized RV aneurysms
  • Endomyocardial biopsy: fibrofatty replacement of myocardial tissue
  • Genetic testing: Multiple genetic abnormalities that can cause ARVC have been identified (e.g., plakoglobin (JUP), desmoplakin (DSP), plakophilin-2 (PKP2), desmoglein-2 (DSG2), desmocollin (DSC2)). [4]

Management [5]

  • Avoid intense physical exertion.
  • Antiarrhythmic treatment
    • Pharmacologic: beta blockers (e.g., sotalol), amiodarone, calcium channel blockers
    • Invasive
      • AICD implantation (in high-risk patients, e.g., patients with left ventricular involvement)
      • Radiofrequency ablation (only as ancillary treatment)
  • Heart transplant (in severe cases that are refractory to all other treatments)
  • Screening and genetic counseling for first-degree relatives [6]
Arrhythmogenic right ventricular cardiomyopathy
Arrhythmogenic right ventricular cardiomyopathy

Heart (transverse section)

The myocardium of the right ventricular wall is largely replaced by fibrotic and adipose tissue (green overlay). The left ventricle is less severely affected. As a result of myocardial thinning, both ventricles are significantly dilated.

These findings are consistent with arrhythmogenic right ventricular cardiomyopathy (ARVC). Despite its name, biventricular involvement in ARVC is common.


Source: “Figure 1A. in: High Resolution Systematic Digital Histological Quantification of Cardiac Fibrosis and Adipose Tissue in Phospholamban p.Arg14del Mutation Associated Cardiomyopathy” by Johannes M. I. H. Gho et al., PLOS ONE Journal, licensed under CC BY 4.0. Modifications: image cropped. The supplementary image with overlays of relevant areas was adapted from the image mentioned above (© AMBOSS).
Comparison of monomorphic and polymorphic ventricular tachycardia (VT), including torsades de pointes
Comparison of monomorphic and polymorphic ventricular tachycardia (VT), including torsades de pointes

Monomorphic VT: QRS morphology is similar throughout, indicating a single arrhythmogenic focus.

Polymorphic VT: QRS morphology varies, indicating multiple arrhythmogenic foci.

Torsades de pointes is a subtype of polymorphic VT occurring in patients with QT prolongation, in which the QRS complexes appear to twist around the isoelectric line.


© AMBOSS

Unclassified cardiomyopathies

Left ventricular noncompaction [7]

  • Definition: rare inherited cardiomyopathy which is associated with structural abnormalities of the left ventricular myocardium (prominent trabeculations and deep intertrabecular recesses)
  • Clinical findings
    • Signs of heart failure and arrhythmia (e.g., dyspnea, edema, chest pain, palpitations, syncope)
    • Thromboembolisms
  • Diagnostics: echocardiography and/or cardiac MRI: LV wall thickening, prominent trabecular meshwork, detection of abnormal flow (within the deep intertrabecular recesses)
  • Treatment: no causal treatment available
    • Avoid intense physical exertion
    • Symptomatic treatment of complications (e.g., heart failure)
    • Prevention of thromboembolism
    • AICD
    • Heart transplant
    • Family and genetic counseling

Arrhythmia-induced cardiomyopathy [8][9]

  • Definition: recurring or persistent atrial or ventricular arrhythmias causing structural cardiac changes and left ventricular dysfunction (potentially reversible)
  • Etiology
    • Supraventricular tachyarrhythmias (i.e., tachycardia, atrial fibrillation, atrial flutter, supraventricular reentry tachycardia)
    • Ventricular tachyarrhythmia (less commonly than supraventricular tachyarrhythmias)
    • Atrial or ventricular ectopy (with or without tachycardia)
  • Clinical features
    • Signs of underlying arrhythmia (e.g., palpitations, syncope)
    • Signs of left heart failure (e.g., dyspnea, chest pain, pulmonary edema)
  • Diagnostics
    • ECG: tachyarrhythmia, ectopic foci
    • Cardiac monitoring (e.g., Holter monitor)
    • Echocardiography and/or cardiac MRI: to evaluate cardiac structure and function (e.g., LVEF measurement)
    • To exclude other causes (e.g., coronary heart disease via coronary angiography)
  • Treatment
    • Beta blockers: management of CHF, rate control in tachyarrhythmias
    • Antiarrhythmics (e.g., amiodarone): rhythm control in tachyarrhythmias
    • Catheter ablation: rhythm control in tachyarrhythmias, ectopic foci

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