2026 ICD-10-CM Diagnosis Code I42.8Other cardiomyopathies
ICD-10-CM Codes›I00–I99›I30-I5A›I42
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 227
- Chronic Condition
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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 112 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myocarditis and cardiomyopathy.
For Medicare Advantage risk adjustment, I42.8 maps to CMS-HCC Category 227 (Cardiomyopathy/Myocarditis) under the V28 model, adding a risk factor of about 0.189 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
I42.8 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
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.
cardiomyopathy I42.8
Cardiomyopathy (familial) (idiopathic) I42.9
newborn I42.8
non-ischemic See Also: by cause; I42.8
obscure of Africa I42.8
specified NEC I42.8
Dysplasia See Also: Anomaly;
Myocardiopathy (congestive) (constrictive) (familial) (hypertrophic nonobstructive) (idiopathic) (infiltrative) (obstructive) (primary) (restrictive) (sporadic) See Also: Cardiomyopathy; I42.9
obscure (African) I42.8
Syndrome See Also: Disease;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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
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Convert I42.8 to ICD-9-CMHistory
Code HistoryHistory
Questions About I42.8Overview
What is the ICD-10 code for other cardiomyopathies?
The ICD-10-CM code for other cardiomyopathies is I42.8 (sometimes written as I428). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
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.
Is I42.8 a CC or MCC?
CMS lists I42.8 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 112 closely related codes in its exclusion list.
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.
What HCC is I42.8?
I42.8 (other cardiomyopathies) maps to CMS-HCC Category 227 (Cardiomyopathy/Myocarditis), commonly written as HCC 227, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 85 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 186.
Does I42.8 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, I42.8 adds a risk adjustment factor of about 0.189 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.145 to 0.200 depending on the payment segment). A more severe related category (HCC 221, HCC 222, HCC 223, HCC 224, HCC 225, and HCC 226) supersedes it when both are reported. See the full factor table on the HCC 227 category page.
