Merck Manual

Please confirm that you are a health care professional

honeypot link

Overview of Cardiomyopathies


Tisha Suboc

, MD, Rush University

Last full review/revision Mar 2021| Content last modified Mar 2021
Click here for Patient Education
Topic Resources

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 figure Forms of cardiomyopathy):

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). It is not classically considered to be in the above-listed categories because it does not describe a primary myocardial disorder.

Manifestations of cardiomyopathies are usually those of heart failure and vary depending on whether there is systolic dysfunction, diastolic dysfunction, or both. Some cardiomyopathies may also cause chest pain, syncope, arrhythmias, or sudden death.

Evaluation typically includes family history, blood tests, ECG, chest x-ray, echocardiography, and cardiac MRI. Some patients require endomyocardial biopsy. Other tests are done as needed to determine the cause. Treatment depends on the specific type and cause of cardiomyopathy (see table Diagnosis and Treatment of Cardiomyopathies).

Forms of cardiomyopathy

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, sudden death,


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, high, normal or low EF ± mitral systolic anterior motion ± asymmetric hypertrophy ± LV gradient

Increased wall thickness ± cavity obliteration

LV diastolic dysfunction



Pulmonary venous congestion

No or mild cardiomegaly

No or mild cardiomegaly


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

Low CO

High EDP ± 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%/year thereafter

About 1% annual risk of sudden death

70% 5-year mortality


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

Beta-blockers ± verapamil ± disopyramide ± septal myotomy ± catheter alcohol ablation

Phlebotomy for hemochromatosis

Endocardial resection

Hydroxyurea for hypereosinophilia

ARNI = angiotensin II receptor blocker and neprilysin inhibitor; 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.

Drugs Mentioned In This Article

Drug Name Select Trade
Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read

Test your knowledge

Cardiac Catherization
Cardiac catheterization of the left or the right heart can be used to do various tests, and it also can be used to determine appropriate therapeutic interventions. Right heart catheterization is most commonly used to assess which of the following? 
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest