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I42.8 ICD-10-CM Code: Other cardiomyopathies

Compare with another code for I42.8Check this code on a claim

Billing Status: NO. This is a non-billable ICD-10-CM code: report a more specific billable code beneath it.

Coding at a Glance

Official instructions
1 inclusion term · 3 Excludes2 · 1 code-first instruction
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 85 · RxHCC V08 category 186

What these terms mean →

Not billable · FY2027A non-billable heading in the tabular list: report a more specific code beneath it.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

Code firstfrom I42Sequence the underlying condition before this code
  • pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4)
Excludes2from I42Not included here; may be reported together
  • ischemic cardiomyopathy (I25.5)
  • peripartum cardiomyopathy (O90.3)
  • ventricular hypertrophy (I51.7)
Includesfrom I42What I42 covers
  • myocardiopathy

Where it sits Source: CMS/NCHS

Under:Chapter 9: Diseases of the Circulatory SystemI30-I5A Other forms of heart diseaseI42 Cardiomyopathy

Codes under I42.8 (2)

  • I42.81Arrhythmogenic cardiomyopathyBillable
  • I42.89Other cardiomyopathies not elsewhere classifiedBillable

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 227 — Cardiomyopathy/Myocarditis

Other models: CMS-HCC V22 HCC 85 · RxHCC V08 HCC 186

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for I42.8 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on I42.8 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • myocardiopathy

Source: inherited from I42

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from I42

Code First

Underlying conditions that must be sequenced before this code.

  • pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4)

Source: inherited from I42

Coder workflow for I42.8

MedCoder structured workflow — derived from this code’s own official record

Before you code I42.8

  1. I42.8 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewI42.81, I42.89

    See the relationships section · Guide: How to choose an ICD-10-CM code →

Choose the right path

  1. Does the documentation support one of the more specific codes beneath I42.8?
    Yes → Select that code and continue the checks below on its own page.
    No → I42.8 cannot be reported as written. Where the codes beneath it include an unspecified code, that code applies when the record goes no further; otherwise query for the missing detail.

    ReviewI42.81, I42.89

  2. Is the underlying (etiologic) condition the Code First note names documented?
    Yes → Sequence the underlying condition first, then the code beneath I42.8.
    No → Continue; do not add an underlying condition the record does not document.

    ReviewO99.4

Report the code beneath I42.8 that the documentation supports, not I42.8 itself. Then confirm that code is valid for the date of service on its own page.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The underlying (etiologic) condition
Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).
Any detail beyond this code’s title
What the record states that a more specific code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes2 — not part of I42.8(3 notes)

    Coding workflow: The conditions named in this note are not included in I42.8. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareI25.5, O90.3, I51.7

    See the official tabular notes · Guidelines I.A.12.b

  • Code First — sequencing check(1 note)

    Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before I42.8. Do not add an underlying condition the record does not document.

    ReviewO99.4

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The underlying condition the Code First note names is documented alongside this condition.

Coding question: How are the two sequenced?

Path: Review the Code First note.

Reason: The underlying condition is sequenced first and the manifestation follows (Guidelines I.A.13).

ReviewO99.4

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse I42.8 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of I42.8 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • I42.9— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Cardiomyopathy, unspecified” takes I42.9; specificity in the record moves it back here.

    Full comparison: I42.8 vs I42.9 →

  • I25.5— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of ischemic cardiomyopathy adds I25.5; it is not part of this code and both may be reported when both are documented.

    Full comparison: I42.8 vs I25.5 →

  • O90.3— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of peripartum cardiomyopathy adds O90.3; it is not part of this code and both may be reported when both are documented.

    Full comparison: I42.8 vs O90.3 →

  • I51.7— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of ventricular hypertrophy adds I51.7; it is not part of this code and both may be reported when both are documented.

    Full comparison: I42.8 vs I51.7 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Other cardiomyopathies is a billable ICD-10-CM diagnosis code (I42.8).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • Not billable as written — a more specific code is required: I42.81, I42.89.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name I42.8 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Code First instruction: I5A — Non-ischemic myocardial injury (non-traumatic) (via I42.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Clinical classification (AHRQ CCSR):CIR005 — Myocarditis and cardiomyopathy (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Cardiomyopathy/Myocarditis) for risk-adjusted payment.

A36.81 — Diphtheritic cardiomyopathy, B33.24 — Viral cardiomyopathy, 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, I42.9 — Cardiomyopathy, unspecified, I43 — Cardiomyopathy in diseases classified elsewhere, I51.4 — Myocarditis, unspecified, I51.5 — Myocardial degeneration

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Heart Failure with Heart Assist Device/Artificial Heart, Acute on Chronic Heart Failure, Acute Heart Failure (Excludes Acute on Chronic), Heart Failure, Except End-Stage and Acute

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Myocarditis and cardiomyopathy).

I25.5 — Ischemic cardiomyopathy, I40.0 — Infective myocarditis, I40.1 — Isolated myocarditis, I40.8 — Other acute myocarditis, I40.9 — Acute myocarditis, unspecified, I41 — Myocarditis in diseases classified elsewhere, 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, I42.9 — Cardiomyopathy, unspecified, I43 — Cardiomyopathy in diseases classified elsewhere, I51.4 — Myocarditis, unspecified, J10.82 — Influenza due to other identified influenza virus with myocarditis, J11.82 — Influenza due to unidentified influenza virus with myocarditis, O90.3 — Peripartum cardiomyopathy, +12 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

HIV Screening Test, Iron Panel, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of I42.8 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run I42.8 with this related code in Claim Check

Hierarchy

Referenced by Code First instructions

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 227 — Cardiomyopathy/Myocarditis [CMS-HCC]— CMS-HCC V28 · 2026

Nearest codes (15)

Change history (2)

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Can I42.8 be billed directly?

No. I42.8 (Other cardiomyopathies) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "I42.8 — Other cardiomyopathies." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/i42.8-other-cardiomyopathies

Change history

Changed in FY2027, the release in force: Became a non-billable header.

  • FY2027 — October 1, 2026
    Became a non-billable header
    FY2027 changes
  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Other cardiomyopathies

Nearest Codes in This Family

Official ICD-10-CM classifications closest to I42.8 in its code family, with their registry titles.

View all codes in the I42 family