Cardiomyopathy (I42) ICD-10-CM
The I42 code range covers cardiomyopathy with 11 ICD-10-CM diagnosis codes. 10 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Includes
This note appears immediately under a three character code title to further define, or give examples of, the content of the category.
- myocardiopathy
Code First
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
- pre-existing cardiomyopathy complicating pregnancy and puerperium O99.4
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
Codes in the I42 Range 11 codes · 10 billable
- I42 CardiomyopathyNon-billable
- I42.0 Dilated cardiomyopathy
- I42.1 Obstructive hypertrophic cardiomyopathy
- I42.2 Other hypertrophic cardiomyopathy
- I42.3 Endomyocardial (eosinophilic) disease
- I42.4 Endocardial fibroelastosis
- I42.5 Other restrictive cardiomyopathy
- I42.6 Alcoholic cardiomyopathy
- I42.7 Cardiomyopathy due to drug and external agent
- I42.8 Other cardiomyopathies
- I42.9 Cardiomyopathy, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the I42 range.
Apical Hypertrophic Cardiomyopathy
A hypertrophic cardiomyopathy characterized by apical hypertrophy, typically LEFT VENTRICULAR HYPERTROPHY (described as ace of spades sign), and deep T-wave inversions in EKG. Clinical symptoms include minor symptoms such as CHEST PAIN; DYSPNEA; and SYNCOPE to more complex symptoms such as ATRIAL FIBRILLATION; VENTRICULAR FIBRILLATION; MYOCARDIAL INFARCTION and CONGESTIVE HEART FAILURE. A transient left ventricular apical hypertrophy is sometimes associated with TAKOTSUBO CARDIOMYOPATHY.
Arrhythmogenic Right Ventricular Dysplasia
A congenital cardiomyopathy that is characterized by infiltration of adipose and fibrous tissue into the RIGHT VENTRICLE wall and loss of myocardial cells. Primary injuries usually are at the free wall of right ventricular and right atria resulting in ventricular and supraventricular arrhythmias.
Cardiomyopathies
A group of diseases in which the dominant feature is the involvement of the CARDIAC MUSCLE itself. Cardiomyopathies are classified according to their predominant pathophysiological features (DILATED CARDIOMYOPATHY; HYPERTROPHIC CARDIOMYOPATHY; RESTRICTIVE CARDIOMYOPATHY) or their etiological/pathological factors (CARDIOMYOPATHY, ALCOHOLIC; ENDOCARDIAL FIBROELASTOSIS).
Cardiomyopathy, Dilated
A form of CARDIAC MUSCLE disease that is characterized by ventricular dilation, VENTRICULAR DYSFUNCTION, and HEART FAILURE. Risk factors include SMOKING; ALCOHOL DRINKING; HYPERTENSION; INFECTION; PREGNANCY; and mutations in the LMNA gene encoding LAMIN TYPE A, a NUCLEAR LAMINA protein.
Cardiomyopathy, Hypertrophic
A form of CARDIAC MUSCLE disease, characterized by left and/or right ventricular hypertrophy (HYPERTROPHY, LEFT VENTRICULAR; HYPERTROPHY, RIGHT VENTRICULAR), frequent asymmetrical involvement of the HEART SEPTUM, and normal or reduced left ventricular volume. Risk factors include HYPERTENSION; AORTIC STENOSIS; and gene MUTATION; (FAMILIAL HYPERTROPHIC CARDIOMYOPATHY).
Cardiomyopathy, Hypertrophic, Familial
An autosomal dominant inherited form of HYPERTROPHIC CARDIOMYOPATHY. It results from any of more than 50 mutations involving genes encoding contractile proteins such as VENTRICULAR MYOSINS; cardiac TROPONIN T; ALPHA-TROPOMYOSIN.
Cardiomyopathy, Restrictive
A form of CARDIAC MUSCLE disease in which the ventricular walls are excessively rigid, impeding ventricular filling. It is marked by reduced diastolic volume of either or both ventricles but normal or nearly normal systolic function. It may be idiopathic or associated with other diseases (ENDOMYOCARDIAL FIBROSIS or AMYLOIDOSIS) causing interstitial fibrosis.
Diabetic Cardiomyopathies
Diabetes complications in which VENTRICULAR REMODELING in the absence of CORONARY ATHEROSCLEROSIS and hypertension results in cardiac dysfunctions, typically LEFT VENTRICULAR DYSFUNCTION. The changes also result in myocardial hypertrophy, myocardial necrosis and fibrosis, and collagen deposition due to impaired glucose tolerance.
Endocardial Fibroelastosis
A condition characterized by the thickening of ENDOCARDIUM due to proliferation of fibrous and elastic tissue, usually in the left ventricle leading to impaired cardiac function (CARDIOMYOPATHY, RESTRICTIVE). It is most commonly seen in young children and rarely in adults. It is often associated with congenital heart anomalies (HEART DEFECTS CONGENITAL;) INFECTION; or gene mutation. Defects in the tafazzin protein, encoded by TAZ gene, result in a form of autosomal dominant familial endocardial fibroelastosis.
Endomyocardial Fibrosis
A condition characterized by the thickening of the ventricular ENDOCARDIUM and subendocardium (MYOCARDIUM), seen mostly in children and young adults in the TROPICAL CLIMATE. The fibrous tissue extends from the apex toward and often involves the HEART VALVES causing restrictive blood flow into the respective ventricles (CARDIOMYOPATHY, RESTRICTIVE).
Glycogen Storage Disease Type IIb
An X-linked dominant multisystem disorder resulting in cardiomyopathy, myopathy and INTELLECTUAL DISABILITY. It is caused by mutation in the gene encoding LYSOSOMAL-ASSOCIATED MEMBRANE PROTEIN 2.
About the I42 Code Range
The ICD-10 code section I42 covers various types of cardiomyopathy, a disease of the heart muscle affecting its structure and function. These codes are used to classify and specify different forms of cardiomyopathy, each with unique causes or characteristics.
This section includes codes for dilated cardiomyopathy (I42.0), often linked to metabolic disorders or infections, and obstructive hypertrophic cardiomyopathy (I42.1), also called hypertrophic obstructive cardiomyopathy, which involves thickened heart muscle blocking blood flow. Other forms like nonobstructive hypertrophic cardiomyopathy (I42.2) cover related hypertrophic conditions without obstruction. The codes also specify restrictive types such as endomyocardial (eosinophilic) disease (I42.3) and endocardial fibroelastosis (I42.4), which cause stiffness in the heart tissue. Additionally, alcoholic cardiomyopathy (I42.6) and cardiomyopathy caused by drugs or toxins (I42.7) are recognized. More rare and other cardiomyopathies fall under I42.8, while unspecified forms use I42.9. Using these codes allows precise documentation of conditions like toxic cardiomyopathy, familial cardiomyopathy, and restrictive cardiomyopathy secondary to infiltrations, ensuring accurate identification of the cardiomyopathy type in healthcare settings.
Questions About This Page
How many billable codes are in the I42 range?
Of the 11 codes in this range, 10 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the I42 range classify?
The range classifies cardiomyopathy. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
