2026 ICD-10-CM Diagnosis Code I42.8Other cardiomyopathies

ICD-10-CM Codes›I00–I99›I30-I5A›I42

ICD-10-CM I42.8
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I42.8 is a billable ICD-10-CM diagnosis code for other cardiomyopathies. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 314 through 316. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myocarditis and cardiomyopathy.

Code Identity

ICD-10-CM Code
I42.8
Billable Status
Yes — Valid for Submission
Code Describes
Other cardiomyopathies
Short Description
Other cardiomyopathies
Same as the full description in the CMS dataset.
Parent Code
I42
Cardiomyopathy

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI42Cardiomyopathy
This CodeI42.8Other cardiomyopathies

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Arrhythmogenic left ventricular cardiomyopathy
  • Arrhythmogenic right ventricular dysplasia
  • Autosomal recessive familial wooly hair
  • Cardiomyopathy
  • Cardiomyopathy due to mucopolysaccharidosis
  • Cardiomyopathy due to storage disease
  • Coenzyme Q10 deficiency
  • Congenital wooly hair
  • Disorder of myocardium associated with rejection of cardiac transplant
  • Disorder of myocardium due to sickle cell hemoglobinopathy
  • Dystrophic cardiomyopathy
  • Familial isolated arrhythmogenic right ventricular dysplasia
  • Fatal infantile mitochondrial cardiomyopathy
  • Histiocytoid mitochondrial cardiomyopathy
  • Histiocytoid mitochondrial cardiomyopathy due to cytochrome aa3 deficiency
  • Hypertrophic mitochondrial cardiomyopathy
  • Hypertrophic mitochondrial cardiomyopathy associated with cataracts and lactic acidosis
  • Hypertrophy of septomarginal trabeculation
  • Infiltrative cardiomyopathy
  • Inflammatory cardiomyopathy
  • Left ventricular myocardial noncompaction cardiomyopathy
  • Lethal left ventricular non-compaction, seizures, hypotonia, cataract, developmental delay syndrome
  • Macrocephaly, intellectual disability, left ventricular non compaction syndrome
  • Maternally inherited mitochondrial cardiomyopathy
  • Maternally inherited mitochondrial cardiomyopathy and myopathy
  • Mitochondrial cardiomyopathy
  • Myocardial degeneration
  • Naxos disease
  • Neonatal encephalomyopathy, cardiomyopathy, respiratory distress syndrome
  • Nonobstructive cardiomyopathy
  • Post-myocarditic cardiomyopathy
  • Primary cardiomyopathy
  • Right ventricular myocardial noncompaction cardiomyopathy
  • TMEM70 related mitochondrial encephalo-cardio-myopathy
  • Valvular cardiomyopathy
  • Ventricular myocardial noncompaction cardiomyopathy

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Becker's
      • cardiomyopathy
    • Cardiomyopathy(familial) (idiopathic)
      • newborn
    • Cardiomyopathy(familial) (idiopathic)
      • non-ischemic
    • Cardiomyopathy(familial) (idiopathic)
      • obscure of Africa
    • Cardiomyopathy(familial) (idiopathic)
      • specified NEC
    • Collagenosis, collagen disease(nonvascular) (vascular)
      • cardiovascular
    • Dysplasia
      • arrhythmogenic right ventricular
    • Dysplasia
      • right ventricular, arrhythmogenic
    • Myocardiopathy(congestive) (constrictive) (familial) (hypertrophic nonobstructive) (idiopathic) (infiltrative) (obstructive) (primary) (restrictive) (sporadic)
      • obscure (African)
    • Newborn(infant) (liveborn) (singleton)
      • affected by
        • cardiomyopathy
    • South African cardiomyopathy syndrome
    • Syndrome
      • South African cardiomyopathy

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR005
Myocarditis and cardiomyopathy
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • 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.

  • 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.

  • 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.

  • Myocardial Degeneration

    degeneration of myocardial tissue.

  • Coenzyme Q10 Deficiency

    a genetically heterogeneous condition, typically inherited in an autosomal recessive fashion, characterized by coenzyme q10 deficiency.

Patient EducationClinical

Cardiomyopathy

Cardiomyopathy is the name for diseases of the heart muscle. These diseases enlarge your heart muscle or make it thicker and more rigid than normal. In rare cases, scar tissue replaces the muscle tissue.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert I42.8 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
425.2 Obsc afric cardiomyopath
Approximate The match is approximate rather than exact.
ICD-9-CM
425.4 Prim cardiomyopathy NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I42.8Overview

Is I42.8 (Cardiomyopathy) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other cardiomyopathies on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I42.8 group to?

When other cardiomyopathies is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, with relative weights from 0.6821 to 2.0852 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I42.8?

Under the General Equivalence Mappings, other cardiomyopathies converts to ICD-9-CM 425.2 (obsc afric cardiomyopath) and 425.4 (prim cardiomyopathy NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.