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I43 ICD-10-CM Code: Cardiomyopathy in diseases classified elsewhere

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
5 Excludes1 · 5 code-first instructions
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 85 · RxHCC V08 category 186

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 314 — OTHER CIRCULATORY SYSTEM DIAGNOSES WITH MCC (MDC 05)
  • MS-DRG 315 — OTHER CIRCULATORY SYSTEM DIAGNOSES WITH CC (MDC 05)
  • MS-DRG 316 — OTHER CIRCULATORY SYSTEM DIAGNOSES WITHOUT CC/MCC (MDC 05)
  • MS-DRG 791 — PREMATURITY WITH MAJOR PROBLEMS (MDC 15)
  • MS-DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

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 I43 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Code First

Underlying conditions that must be sequenced before this code.

  • underlying disease, such as:
  • amyloidosis (E85.-)
  • glycogen storage disease (E74.0-)
  • gout (M10.0-)
  • thyrotoxicosis (E05.0-E05.9-)

Coder workflow for I43

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

Before you code I43

  1. I43 is a manifestation code (“in diseases classified elsewhere”). Confirm the underlying condition is documented and sequence it first; a manifestation code is not reported as the first-listed or principal diagnosis. The etiology/manifestation convention (Guidelines I.A.13).

    See the official tabular notes · Guide: Manifestation codes and Code First sequencing →

  2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with I43. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in I43’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewB33.24, A36.81, D86.85, A18.84

  2. Is the underlying (etiologic) condition the Code First note names documented?
    Yes → Sequence the underlying condition first, then I43.
    No → A manifestation code needs its underlying condition — query before reporting it.

    ReviewE85, E74.0, M10.0

Consider I43. Then confirm the code is valid for the date of service in the Verify section.

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).

Official instructions as workflow

  • Excludes1 — check before selecting I43(5 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with I43: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareB33.24, A36.81, D86.85, A18.84

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

  • Code First — sequencing check(5 notes)

    Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before I43. Do not add an underlying condition the record does not document.

    ReviewE85, E74.0, M10.0

    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: Both the condition I43 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewB33.24, A36.81, D86.85, A18.84

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).

ReviewE85, E74.0, M10.0

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.

Code Overview

Cardiomyopathy in diseases classified elsewhere is a billable ICD-10-CM diagnosis code (I43).

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

  • Principal-diagnosis restriction. This is a manifestation code: the Medicare Code Editor requires the underlying condition (etiology) to be sequenced first, with this code reported after it.
  • CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

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 structured relationships — computed from published CMS and AHRQ datasets

Other codes that name I43 or its code family, from the CMS ICD-10-CM tabular instructional notes and the CMS ICD-10-CM Index to Diseases and Injuries. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 2 Use Additional Code instructions: M10 — Gout, M1A — Chronic gout.

These codes instruct coders to additionally report this code when it applies.

Referenced by 5 Index etiology/manifestation pairs across 2 chapters: E63.9 — Nutritional deficiency, unspecified, E88.9 — Metabolic disorder, unspecified, G11.11 — Friedreich ataxia, G71.09 — Other specified muscular dystrophies, G71.11 — Myotonic muscular dystrophy.

The ICD-10-CM Index lists these etiology codes with this code in brackets — the manifestation, reported second.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 112 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 5 MS-DRGs: DRG 314 (MDC 05), DRG 315 (MDC 05), DRG 316 (MDC 05), DRG 791 (MDC 15), DRG 793 (MDC 15).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

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

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 clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

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, I44.0 — Atrioventricular block, first degree, I44.1 — Atrioventricular block, second degree, I44.30 — Unspecified atrioventricular block, I44.39 — Other atrioventricular block, I45.2 — Bifascicular block, I45.3 — Trifascicular block, I45.4 — Nonspecific intraventricular block, I45.81 — Long QT syndrome, I45.89 — Other specified conduction disorders, I48.0 — Paroxysmal atrial fibrillation, +92 more

Principal diagnosis restriction (Medicare Code Editor)

Manifestation code — the underlying condition is sequenced first.

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, I42.8 — Other cardiomyopathies, I42.9 — Cardiomyopathy, unspecified, 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, I42.8 — Other cardiomyopathies, I42.9 — Cardiomyopathy, unspecified, 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.

Iron Panel, Prothrombin Time Test and INR (PT/INR), Thyroid Stimulating Hormone (TSH)

Contextual Map

Every relationship of I43 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 I43 with these 10 related codes in Claim Check

Hierarchy

Excludes1

Code First

Referenced by Use Additional Code instructions

  • M10 — Gout[Use Additional Code]: “Cardiomyopathy in diseases classified elsewhere (I43)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • M1A — Chronic gout[Use Additional Code]: “Cardiomyopathy in diseases classified elsewhere (I43)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Index etiology/manifestation pairs

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

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

MS-DRG Grouper

MDC crossing

  • MDC 05 — Diseases and Disorders of the Circulatory System[MDC crossing]: “Diseases and Disorders of the Circulatory System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 17,209 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
  • MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

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 FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 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 structured 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 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.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

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. "I43 — Cardiomyopathy in diseases classified elsewhere." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/i43-cardiomyopathy-in-diseases-classified-elsewhere

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Cardiomyopathy in diseases classified elsewhere

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.