Cardiomyopathy

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	Cardiomyopathy;
	Opened left ventricle of heart shows a thickened, dilated left ventricle with subendocardial fibrosis manifested as increased whiteness of endocardium {Autopsy findings}. ; Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology
ICD-10	I42.0
ICD-9	425.4
DiseasesDB	2137
MeSH	D009202

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Overview

Cardiomyopathy, which literally means "heart muscle disease", is the deterioration of the function of the myocardium (i.e., the actual heart muscle) for any reason. People with cardiomyopathy are often at risk of arrhythmia or sudden cardiac death or both.^[1]

Cardiomyopathies can generally be categorized into two groups, based on World Health Organization guidelines: extrinsic cardiomyopathies and intrinsic cardiomyopathies.^[2]

In general definition;

Cardiomyopathies are myocardial diseases that independent of:

Congenital Heart Disease
Pericardial Disease
Pulmonary hypertension / Systemic hypertension
Heart valve disease

Extrinsic cardiomyopathies

These are cardiomyopathies where the primary pathology is outside the myocardium itself. Most cardiomyopathies are extrinsic, because by far the most common cause of a cardiomyopathy is ischemia. The World Health Organization calls these specific cardiomyopathies:^[2]

Alcoholic cardiomyopathy
Coronary Artery Disease
Congenital Heart Disease
Hypophosphatemia mediated myonecrosis as part of the refeeding syndrome
Inflammatory cardiomyopathy
Ischemic cardiomyopathy
Hypertensive cardiomyopathy
Nutritional Diseases
Systemic metabolic disease
Valvular cardiomyopathy

Ischemic cardiomyopathy

Ischemic cardiomyopathy is a weakness in the muscle of the heart due to inadequate oxygen delivery to the myocardium with coronary artery disease being the most common cause. Anemia and sleep apnea are relatively common conditions that can contribute to ischemic myocardium and hyperthyroidism can cause a 'relative' ischemia secondary to high output heart failure. Individuals with ischemic cardiomyopathy typically have a history of myocardial infarction (heart attack), although longstanding ischemia can cause enough damage to the myocardium to precipitate a clinically significant cardiomyopathy even in the absence of myocardial infarction. In a typical presentation, the area of the heart affected by a myocardial infarction will initially become necrotic as it dies, and will then be replaced by scar tissue (fibrosis). This fibrotic tissue is akinetic; it is no longer muscle and cannot contribute to the heart's function as a pump. If the akinetic region of the heart is substantial enough, the affected side of the heart (i.e. the left or right side) will go into failure, and this failure is the functional result of an ischemic cardiomyopathy.

Cardiomyopathy due to systemic diseases

Many diseases can result in cardiomyopathy. These include diseases like hemochromatosis, (an abnormal accumulation of iron in the liver and other organs), amyloidosis (an abnormal accumulation of the amyloid protein), diabetes, hyperthyroidism, lysosomal storage diseases and the muscular dystrophies.

Intrinsic cardiomyopathies

An intrinsic cardiomyopathy is weakness in the muscle of the heart that is not due to an identifiable external cause. To make a diagnosis of an intrinsic cardiomyopathy, significant coronary artery disease should be ruled out (amongst other things). The term intrinsic cardiomyopathy does not describe the specific etiology of weakened heart muscle. The intrinsic cardiomyopathies are a mixed-bag of disease states, each with their own causes.

Intrinsic cardiomyopathy has a number of causes including drug and alcohol toxicity, certain infections (including Hepatitis C), and various genetic and idiopathic (i.e., unknown) causes.

Intrinsic cardiomyopathies are generally classified into four types,^[2]^[3] but additional types are also recognized:

Dilated cardiomyopathy (DCM), the most common form, and one of the leading indications for heart transplantation. In DCM the heart (especially the left ventricle) is enlarged and the pumping function is diminished. Approximately 40% of cases are familial, but the genetics are poorly understood compared with HCM. In some cases it manifests as peripartum cardiomyopathy, and in other cases it may be associated with alcoholism.
Hypertrophic cardiomyopathy (HCM or HOCM), a genetic disorder caused by various mutations in genes encoding sarcomeric proteins. In HCM the heart muscle is thickened, which can obstruct blood flow and prevent the heart from functioning properly.
Arrhythmogenic right ventricular cardiomyopathy (ARVC) arises from an electrical disturbance of the heart in which heart muscle is replaced by fibrous scar tissue. The right ventricle is generally most affected.
Restrictive cardiomyopathy (RCM) is an uncommon cardiomyopathy. The walls of the ventricles are stiff, but may not be thickened, and resist the normal filling of the heart with blood. A rare form of restrictive cardiomyopathy is the obliterative cardiomyopathy, seen in the hypereosinophilic syndrome. In this type of cardiomyopathy, the myocardium in the apices of the left and right ventricles becomes thickened and fibrotic, causing a decrease in the volumes of the ventricles and a type of restrictive cardiomyopathy.
Noncompaction cardiomyopathy has been recognized as a separate type since the 1980s. The term refers to a cardiomyopathy where the left ventricle wall has failed to grow properly from birth and has a spongy appearance when viewed during an echocardiogram.

Alternate Detailed Classification Schemes

There are other more detailed classification schemes with a more complete Differential diagnosis as shown below:

Clinical Classification

DILATED (D):
- Left and/or right ventricular enlargement
- Impaired systolic function
- Congestive heart failure
- Arrhythmias
- Emboli
RESTRICTIVE (R):
- Endomyocardial scarring or myocardial infiltration resulting in restriction to left and/or right ventricular filling.
HYPERTROPHIC (H):
- Disproportionate left ventricular hypertrophy
  Typically involving septum more than free wall
  
  With or without an intraventricular systolic pressure gradient
  Usually of a nondilated left ventricular cavity

PRIMARY MYOCARDIAL INVOLVEMENT

Idiopathic (D,R,H)
Hereditary (D,R,H)
- Up to 20% of dilated cardiomyopathy
- Dominant, recessive, and x-linked
Eosinophilic Endomyocardial Disease (R)
Endomyocardial Fibrosis (R)

SECONDARY MYOCARDIAL INVOLVEMENT

Sensitivity and toxic reactions (Dilated cardiomyopathy)
- Alcohol
- Cocaine
- Radiation
- Doxorubicin
Metabolic (Dilated cardiomyopathy)
- Selenium Deficiency
- Hypophosphatemia
- Hypocalcemia
- Thyroid Disease
Infectious (Dilated cardiomyopathy)
Familial Storage Disease (Dilated cardiomyopathy, Restrictive cardiomyopathy)
Connective Tissue Disorders (Dilated cardiomyopathy)
Infiltrative and Granulomatous (Restrictive cardiomyopathy, Dilated cardiomyopathy)
Neuromuscular (Dilated cardiomyopathy)
Other (Dilated cardiomyopathy)
- Uncontrolled Tachycardia
- Right Ventricular Dysplasia
Peripartum Heart Disease (Dilated cardiomyopathy)

Differential Diagnosis of Causes of Cardiomyopathy

Primary Cardiomyopathies

Endomyocardial fibrosis
Eosinophilic endomyocardial disease
Familial
Idiopathic

Secondary Cardiomyopathies

Acromegaly
Adenoviruses
Amebiasis
Amyloidosis
Angiomas
Arboviruses
Ascariasis
Aspergillosis
Beta hemolyzing streptococci
Blastomycosis
Borrelia burgdorferi
Brucella
Cardiac transplant rejection
Carnitine deficiency
Chagas Disease
Coccidioidomycosis
Coxsackie virus A
Coxsackie virus B1-B5
Chronic tachycardia
Cryptococcosis
Cushing's Disease
Cysticercosis
Cytomegalovirus (CMV)
Dermatomyositis
Diabetes Mellitus
Diptheria
Drug-induced allergy
Drugs, toxins
Echinococcosis
ECHO viruses (EnteroCytopathogenic Human Orphan viruses)
Electric shock
Electrolyte imbalances
Enterococci
Epstein-Barr Virus (EBV)
Fabry's Disease
Filariasis
Flavivirus
Friedrich's Ataxia
Gangliosidosis
Gaucher's Disease
Giant Cell Myocarditis
Glycogen storage diseases
Gout
Hand-Schuller-Christian Syndrome
Heatstroke
Hemochromatosis
Hepatitis
Histoplasmosis
HIV
Hunter's Syndrome
Hurler's Syndrome
Hyperparathyroidism
Hyperthyroidism
Hypothermia
Hypothyroidism
Idiopathic
Influenza
Irradiation
Kawasaki's Disease
Leishmaniasis
Leptospirosis
Leukemia
Lightening strike
Lyme Disease
Malaria
Measles
Mucopolysaccharidosis
Mumps
Muscular Dystrophy
Myotonic Dystrophy
Myxomas
Neimann-Pick Disease
Niacin deficiency
Obesity
Oral candidiasis
Oxalosis
Pertussis
Pheochromocytoma
Polio
Polyarteritis Nodosa
Polycythemic Vera
Porphyria
Postpartal cardiomyopathy
Psittacosis
Q Fever
Rabies
Refsum's Disease
Rhabdomyomas
Rheumatic Fever
Rheumatoid Arthritis
Rocky Mountain Spotted Fever
Sacrosporidiosis
Sarcoidosis
Sarcomas
Schistosomiasis
Scleroderma
Selenium deficiency
Sickle Cell Anemia
Staphylococcus
Syphilis
Systemic Lupus Erythematosus
Tetanus
Thrombotic Thrombocytopenic Purpura
Toxoplasmosis
Trauma
Trichinosis
Tuberculosis
Typhoid Fever
Uremia
Varicella-zoster virus
Vitamin B deficiency
Vitamin C deficiency
Vitamin D overdose
Whipple's Disease

Treatment

Treatment depends on the type of cardiomyopathy, but may include medication, implanted pacemakers, defribillators, or ventricular assist devices (LVADs), or ablation. The goal of treatment is often symptom relief, and some patients may eventually require a heart transplant. Treatment of cardiomyopathy (and other heart diseases) using alternative methods such as stem cell therapy is commercially available but is not supported by convincing evidence.

Genetic causes of cardiomyopathy

Phenotype	Inheritance pattern	Chromosomal locus	Gene	Protein	Skeletal myopathy
Dilated cardiomyopathy	X-linked	Xp21	dystrophin	Dystrophin	Duchenne / Becker muscular dystrophy
	X-linked	Xq28	G4.5	Tafazzin	Barth syndrome
	Autosomal dominant	15q14	actin	Actin	Nemaline myopathy
		2q35	desmin	Desmin	Desmin myopathy
		5q33	δ-sarcoglycan	δ-sarcoglycan	Limb girdle muscular dystrophy 2F
		1q32	Troponin T	Troponin T
		14q11	β-myosin heavy chain	β-myosin heavy chain
		15q2	α-tropomyosin	α-tropomyosin	Nemaline myopathy
		Midna	Mitochondrial respiratory chain	Mitochondrial respiratory chain	Mitochondrial myopathy
Dilated cardiomyopathy with conduction disease	Autosomal dominant	1q21	lamin A/C	Lamin A/C	Emery-Dreifuss muscular dystrophy
Hypertrophic cardiomyopathy	Autosomal dominant	14q11	β-myosin heavy chain	β-myosin heavy chain
		14q11	β-myosin heavy chain	β-myosin heavy chain
		1q32	Troponin T	Troponin T
		12q23	Troponin T	Troponin T
		15q2	α-tropomyosin	α-tropomyosin	Nemaline myopathy
		11q11	myosin-binding protein C	myosin-binding protein C
		3p21	myosin essential light chain	myosin essential light chain
		3p21	myosin regulatory light chain	myosin regulatory light chain
		2p31	titin	Titin
Hypertrophic cardiomyopathy with Wolf-Parkinson-White syndrome		7q3	AMPK	AMPK
		MIDINA	Mitochondrial respiratory chain	Mitochondrial respiratory chain	Mitochondrial myopathy
Left ventricular noncompaction	X-linked	Xq28	G4.5	Tafazzin	Barth syndrome
	Autosomal dominant	18q12	α-dystrobrevin	α-dystrobrevin	Muscular dystrophy

Table from article *"The Failing Heart". Nature. June 15, 2007

Gross Pathological Findings

Images shown below are courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology

Cardiomyopathy: Gross excellent view of mitral valve from left atrium anterior leaflet appears to balloon a bit into the atrium
Cardiomyopathy: Gross excellent view of mitral and tricuspid valves from atria, appear normal anatomy.

Cardiomyopathy: Gross apical slice of left and right ventricles concentric hypertrophy with cavitary obliteration sudden unexpected death obstructive cardiomyopathy
Dilated Cardiomyopathy: Gross natural color close-up view of heart surgically removed for a transplantation shows aortic valve and anterior leaflet of mitral valve with cholesterol deposits endocardium of left ventricle is diffusely thickened

Cardiomyopathy: Gross montage of ventricular slices showing hypertrophy and about normal ventricular lumen size a hypertrophic non-dilated cardiomyopathy
Cardiomyopathy: Gross ventricular slices hypertrophy and extensive myocardial fibrosis a unique case of global fiber disarray with atrophy and fibrosis

Cardiomyopathy: Gross close up view of a ventricle slice
Cardiomyopathy: Gross excellent ventricular slice with hypertrophy and fibrosis a unique case of global fiber disarray with hypertrophy then atrophy and then fibrosis

Cardiomyopathy: Gross external view of globular heart with patchy fibrosis seen through epicardium
Cardiomyopathy: Gross interventricular septum showing asymmetrical hypertrophy in posterior septum

Cardiomyopathy: Gross hypertrophic cardiomyopathy obstructive excellent section through left ventricle outlet to show subvalvular narrowing case of sudden death in a 27 yo male playing basketball no history of disease
Cardiomyopathy: Gross obstructive cardiomyopathy showing aorta outflow tract with marked endocardial thickening mitral valve appears normal (Same case as previous one)

Cardiomyopathy: Gross excellent view of mitral valve atrial surface showing thickening which is fibrous in body of valve and myxoid at area of free margin changes presumed secondary to insufficiency due to anterior motion
Cardiomyopathy: Gross dilated left ventricle with marked endocardial thickening this is what has been called adult fibroelastosis

Dilated Cardiomyopathy: Gross good example huge dilated left ventricle
Dilated Cardiomyopathy: Gross dilated left ventricle with marked endocardial sclerosis (an excellent example)

Cardiomyopathy: Gross intact globular shaped heart
Dilated Cardiomyopathy: Gross opened left ventricle dilated with endocardial thickening good example

Cardiomyopathy: Gross globular heart external view 10 year old girl with sickle cell anemia
Cardiomyopathy: Gross horizontal sections of ventricles dilation type 10 year old girl with sickle cell anemia

Cardiomyopathy: Intermediate between hypertrophic and dilated
Cardiomyopathy Asymmetrical Septal Hypertrophy

Dilated Cardiomyopathy: Gross opened globular left ventricle natural color (very good example)
Diabetic Cardiomyopathy: Gross natural color moderately hypertrophied heart shown in horizontal section hyperemic subendocardium has no microscopic lesion long standing type I diabetic patient, no significant coronary artery lesions, congestive heart failure

Brain: Infarct: Healing large MCA and PICA probably embolic 64 year old female chronic obstructive pulmonary disease and cardiomyopathy with atrial fibrillation
Kidney: Infarct Remote: Gross external view with capsule removed two old and very typical infarct scars 27yobf with dilated cardiomyopathy

Dilated Cardiomyopathy: Gross natural color external view globular heart 500 gm 24yo female seven pregnancies
Excessive pedal edema due to right heart failure in a patient with hypertrophic cardiomyopathy (due to functional aortic stenosis from narrow outflow tract)

Microscopic Pathological Findings