2026 ICD-10-CM Diagnosis Code I42.0Dilated cardiomyopathy

ICD-10-CM Codes›I00–I99›I30-I5A›I42

ICD-10-CM I42.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I42.0 is a billable ICD-10-CM diagnosis code for dilated cardiomyopathy. 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, I42.0 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

ICD-10-CM Code
I42.0
Billable Status
Yes — Valid for Submission
Code Describes
Dilated cardiomyopathy
Short Description
Dilated cardiomyopathy
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 CodeI42.0Dilated cardiomyopathy

Medicare Risk Adjustment (HCC)Billing

I42.0 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.

CMS-HCC V28 Category (Payment Model)
HCC 227— Cardiomyopathy/Myocarditis
Payment HCC · PY 2026 one of 14 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.189
community, non-dual, aged · ranges 0.145–0.200 across segments
Hierarchy
Superseded by HCC 221, HCC 222, HCC 223, HCC 224, HCC 225, and HCC 226
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 85
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 85 · ESRD (V21): HCC 85 · ESRD (V24): HCC 85
ESRD V21 weights: 0.082 dialysis, 0.186–0.336 functioning graft · ESRD V24 weights: 0.063 dialysis, 0.169–0.302 functioning graft
Part D (RxHCC)
RxHCC 186 — Heart Failure
also risk-adjusts in the Part D prescription drug model (V08)

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.

  • Autosomal dominant epidermolysis bullosa simplex
  • Autosomal recessive familial wooly hair
  • Cardiomyopathy caused by drug
  • Cardiomyopathy due to connective tissue disease
  • Cardiomyopathy due to mucopolysaccharidosis
  • Cardiomyopathy due to storage disease
  • Cardiomyopathy due to viral infection
  • Cardiomyopathy in Friedreich's ataxia
  • Cardiomyopathy in myotonic dystrophy
  • Cardiomyopathy with cataract and hip spine disease syndrome
  • Cardiovascular abnormality due to infective myocarditis
  • Congenital wooly hair
  • Congestive obstructive cardiomyopathy
  • Dilated cardiomyopathy
  • Dilated cardiomyopathy 3B
  • Dilated cardiomyopathy caused by anthracycline
  • Dilated cardiomyopathy caused by drug
  • Dilated cardiomyopathy caused by radiation
  • Dilated cardiomyopathy due to amyloidosis
  • Dilated cardiomyopathy due to bacterial myocarditis
  • Dilated cardiomyopathy due to carnitine deficiency
  • Dilated cardiomyopathy due to dermatomyositis
  • Dilated cardiomyopathy due to electrolyte imbalance
  • Dilated cardiomyopathy due to familial storage disease
  • Dilated cardiomyopathy due to Friedreich's ataxia
  • Dilated cardiomyopathy due to fungal myocarditis
  • Dilated cardiomyopathy due to glycogen storage disease
  • Dilated cardiomyopathy due to granuloma
  • Dilated cardiomyopathy due to hemochromatosis
  • Dilated cardiomyopathy due to infectious disease
  • Dilated cardiomyopathy due to infiltration
  • Dilated cardiomyopathy due to lysosomal storage disease
  • Dilated cardiomyopathy due to malignancy
  • Dilated cardiomyopathy due to metabolic disorder
  • Dilated cardiomyopathy due to mitochondrial disease
  • Dilated cardiomyopathy due to mucopolysaccharidosis
  • Dilated cardiomyopathy due to muscular dystrophy
  • Dilated cardiomyopathy due to myotonic dystrophy
  • Dilated cardiomyopathy due to neuromuscular disorder
  • Dilated cardiomyopathy due to nutritional deficiency
  • Dilated cardiomyopathy due to parasitic myocarditis
  • Dilated cardiomyopathy due to phytanic acid storage disease
  • Dilated cardiomyopathy due to polyarteritis nodosa
  • Dilated cardiomyopathy due to protozoan myocarditis
  • Dilated cardiomyopathy due to rheumatoid arthritis
  • Dilated cardiomyopathy due to sarcoidosis
  • Dilated cardiomyopathy due to scleroderma
  • Dilated cardiomyopathy due to systemic sclerosis
  • Dilated cardiomyopathy due to taurine deficiency
  • Dilated cardiomyopathy due to viral myocarditis
  • Dilated cardiomyopathy with connective tissue disorder
  • Dilated cardiomyopathy with genetic marker
  • Dilated cardiomyopathy with hypergonadotropic hypogonadism syndrome
  • Erythrokeratodermia cardiomyopathy syndrome
  • Familial cardiomyopathy
  • Familial dilated cardiomyopathy with conduction defect due to LMNA mutation
  • Heart disease caused by ionizing radiation
  • Infiltrative cardiomyopathy
  • Intermediate epidermolysis bullosa simplex with cardiomyopathy
  • Ischemic congestive cardiomyopathy
  • Ischemic dilated cardiomyopathy due to coronary artery disease
  • Microcephalus cardiomyopathy syndrome
  • Nonischemic congestive cardiomyopathy
  • Nonsenile cataract
  • Primary dilated cardiomyopathy
  • Primary familial dilated cardiomyopathy
  • Primary idiopathic dilated cardiomyopathy
  • Secondary dilated cardiomyopathy
  • Secondary nonischemic congestive cardiomyopathy
  • Sensorineural deafness with dilated cardiomyopathy syndrome
  • Toxic cardiomyopathy
  • Toxic dilated cardiomyopathy
  • Wooly hair and palmoplantar keratoderma with dilated cardiomyopathy syndrome

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Congestive cardiomyopathy

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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

  • Intermediate Epidermolysis Bullosa Simplex with Cardiomyopathy

    an autosomal dominant condition caused by mutation(s) in the klhl24 gene, encoding kelch-like protein 24. it is characterized by epidermolysis bullosa and dilated cardiomyopathy.

  • Myocardial Degeneration

    degeneration of myocardial tissue.

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 I42.0 to ICD-9-CMHistory

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

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 I42.0Overview

What is the ICD-10 code for dilated cardiomyopathy?

The ICD-10-CM code for dilated cardiomyopathy is I42.0 (sometimes written as I420). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is I42.0 (Cardiomyopathy) a billable code?

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

What MS-DRG does I42.0 group to?

When dilated cardiomyopathy 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 I42.0 a CC or MCC?

CMS lists I42.0 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 I42.0?

Under the General Equivalence Mappings, dilated cardiomyopathy converts to ICD-9-CM 425.4 (prim cardiomyopathy NEC). The mapping is approximate, so confirm the match fits the documentation.

What HCC is I42.0?

I42.0 (dilated cardiomyopathy) 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 I42.0 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, I42.0 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.