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Overview of Cardiomyopathies

By J. Malcolm O. Arnold, MD, Physiology and Pharmacology, University of Western Ontario;University Hospital, London Health Sciences Center

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A cardiomyopathy is a primary disorder of the heart muscle. It is distinct from structural cardiac disorders such as coronary artery disease, valvular disorders, and congenital heart disorders. Cardiomyopathies are divided into 3 main types based on the pathologic features: (see see Figure: Forms of cardiomyopathy.)

  • Dilated

  • Hypertrophic

  • Restrictive

The term ischemic cardiomyopathy refers to the dilated, poorly contracting myocardium that can occur in patients with severe coronary artery disease (with or without areas of infarction). Although it does not describe a primary myocardial disorder, the term remains in common use.

Manifestations of cardiomyopathies are usually those of heart failure and vary depending on whether there is systolic dysfunction, diastolic dysfunction, or both (see Heart Failure : Pathophysiology). Some cardiomyopathies may also cause chest pain, syncope, or sudden death.

Evaluation typically includes blood tests, ECG, chest X-ray, echocardiography and often MRI if available. Some patients require endomyocardial biopsy (transvenous right ventricular or retrograde left ventricular). Other tests are done as needed to determine the cause. Treatment depends on the specific type and cause of cardiomyopathy (see Diagnosis and Treatment of Cardiomyopathies).

Forms of cardiomyopathy.

Diagnosis and Treatment of Cardiomyopathies

Feature or Method





Systolic dysfunction

Diastolic dysfunction ± outflow obstruction

Diastolic dysfunction

Clinical findings

LV and RV failure


Functional AV valve regurgitation

S3 and/or S4

Exertional dyspnea, angina, syncope, sudden death

Systolic murmur ± mitral regurgitation murmur, S4

Bifid carotid pulse with a brisk upstroke and rapid downstroke

Exertional dyspnea and fatigue

LV ± RV failure

Functional AV valve regurgitation


Nonspecific ST- and T-wave abnormalities

Q waves ± BBB

LV hypertrophy and ischemia

Deep septal Q waves

LV hypertrophy or low QRS voltage


Dilated hypokinetic ventricles ± mural thrombus

Low EF and, frequently, functional AV valve regurgitation

Hypertrophied ventricle ± mitral systolic anterior motion ± asymmetric hypertrophy ± LV gradient

Increased wall thickness ± cavity obliteration

LV diastolic dysfunction



Pulmonary venous congestion

No cardiomegaly

No or mild cardiomegaly


Normal or high EDP, low EF, diffusely dilated hypokinetic ventricles ± AV valve regurgitation

Low CO

High EDP, high EF ± outflow subvalvular gradient ± mitral regurgitation

Normal or low CO

High EDP, dip and plateau diastolic LV pressure curve

Normal or low CO


20% mortality in first year, and about 10%/yr thereafter

About 1% annual risk of sudden death

70% 5-yr mortality


Diuretics, ACE inhibitors, angiotensin II receptor blockers, β-blockers, spironolactone or eplerenone, digoxin, ICD, cardiac resynchronization therapy, anticoagulants

β-blockers ± verapamil ± disopyramide ± septal myotomy ± catheter alcohol ablation; AV pacing

Phlebotomy for hemochromatosis

Endocardial resection

Hydroxyurea for hypereosinophilia

AV = atrioventricular; BBB = bundle branch block; CO = cardiac output; EDP = end-diastolic pressure; EF = ejection fraction; ICD = implantable cardioverter-defibrillator ; LV = left ventricular; RV = right ventricular; S3 = 3rd heart sound; S4= 4th heart sound; ±= with or without.

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