Overview of Cardiomyopathies: Cardiomyopathies: Merck Manual Professional


	Sections		Cardiovascular Disorders

	Chapters		Cardiomyopathies

Overview of Cardiomyopathies

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: dilated, hypertrophic, and restrictive (see Fig. 1: Cardiomyopathies: Forms of cardiomyopathy.) based on the pathologic features. The term ischemic cardiomyopathy refers to the dilated, poorly contracting myocardium that sometimes occurs 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 ECG and echocardiography and sometimes MRI. 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 Table 1: Cardiomyopathies: Diagnosis and Treatment of Cardiomyopathies).

Fig. 1

Forms of cardiomyopathy.

Table 1

Print Open table in new window

Diagnosis and Treatment of Cardiomyopathies
Feature or Method	Dilated	Hypertrophic	Restrictive
Pathophysiology	Systolic dysfunction	Diastolic dysfunction ± outflow obstruction	Diastolic dysfunction
Clinical findings	LV and RV failure Cardiomegaly Functional AV valve regurgitation S₃ and S₄	Exertional dyspnea, angina, syncope, sudden death Ejection ± mitral regurgitation murmurs, S₄ Bifid carotid pulse with a brisk upstroke and rapid downstroke	Exertional dyspnea and fatigue LV ± RV failure Functional AV valve regurgitation
ECG	Nonspecific ST- and T-wave abnormalities Q waves ± BBB	LV hypertrophy and ischemia Deep septal Q waves	LV hypertrophy or low voltage
Echocardiography	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
X-ray	Cardiomegaly Pulmonary venous congestion	No cardiomegaly	No or mild cardiomegaly
Hemodynamics	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
Prognosis	20% mortality in first year, and about 10%/yr thereafter	About 1% annual risk of sudden death	70% 5-yr mortality
Treatment	Diuretics, ACE inhibitors, angiotensin II receptor blockers, β-blockers, spironolactone or eplerenone, digoxin, ICD, biventricular pacing, 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.

Last full review/revision January 2010 by J. Malcolm O. Arnold, MD