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I01.2 ICD-10-CM Code: Acute rheumatic myocarditis

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

Coding at a Glance

Tabular directives
1 inclusion term · 1 Excludes1

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)

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.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for I01.2 in the official ICD-10-CM tabular list, quoted as published.

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

Notes without a marker are published on I01.2 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Any condition in I00 with myocarditis

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).

  • chronic diseases of rheumatic origin (I05-I09) unless rheumatic fever is also present or there is evidence of reactivation or activity of the rheumatic process. Compare I01.2 vs I05 →

Source: inherited from I01

Coder workflow for I01.2

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

Before you code I01.2

  1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with I01.2. 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 I01.2’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.

Consider I01.2. 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).
Acuity
Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).

Official instructions as workflow

  • Excludes1 — check before selecting I01.2(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with I01.2: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

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

Coding decision scenarios

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

Documentation: Both the condition I01.2 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).

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

Acute rheumatic myocarditis is a billable ICD-10-CM diagnosis code (I01.2).

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

Indexed Clinical Terms (8)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • 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 I01.2 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 2 Excludes1 notes: I00 — Rheumatic fever without heart involvement, I40 — Acute myocarditis.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Excludes2 note: I51 — Complications and ill-defined descriptions of heart disease (via I01.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

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 30 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 314 (MDC 05), DRG 315 (MDC 05), DRG 316 (MDC 05).

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

Clinical classification (AHRQ CCSR):CIR002 — Acute rheumatic heart disease (default); 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.

A52.06 — Other syphilitic heart involvement, B33.20 — Viral carditis, unspecified, B33.21 — Viral endocarditis, B33.22 — Viral myocarditis, I00 — Rheumatic fever without heart involvement, I01.8 — Other acute rheumatic heart disease, I01.9 — Acute rheumatic heart disease, unspecified, I09.0 — Rheumatic myocarditis, I09.9 — Rheumatic heart disease, unspecified, I23.0 — Hemopericardium as current complication following acute myocardial infarction, I23.1 — Atrial septal defect as current complication following acute myocardial infarction, I23.2 — Ventricular septal defect as current complication following acute myocardial infarction, I23.3 — Rupture of cardiac wall without hemopericardium as current complication following acute myocardial infarction, I23.6 — Thrombosis of atrium, auricular appendage, and ventricle as current complications following acute myocardial infarction, I23.7 — Postinfarction angina, I23.8 — Other current complications following acute myocardial infarction, I27.841 — Fontan-associated lymphatic dysfunction, I27.848 — Other Fontan-associated condition, I27.849 — Fontan related circulation, unspecified, I40.0 — Infective myocarditis, +9 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Acute rheumatic heart disease, Myocarditis and cardiomyopathy).

A39.52 — Meningococcal myocarditis, B26.82 — Mumps myocarditis, B33.20 — Viral carditis, unspecified, B33.22 — Viral myocarditis, B33.24 — Viral cardiomyopathy, B58.81 — Toxoplasma myocarditis, D86.85 — Sarcoid myocarditis, I00 — Rheumatic fever without heart involvement, I01.0 — Acute rheumatic pericarditis, I01.1 — Acute rheumatic endocarditis, I01.8 — Other acute rheumatic heart disease, I01.9 — Acute rheumatic heart disease, unspecified, I02.0 — Rheumatic chorea with heart involvement, I02.9 — Rheumatic chorea without heart involvement, I09.0 — Rheumatic myocarditis, I25.5 — Ischemic cardiomyopathy, I40.0 — Infective myocarditis, I40.1 — Isolated myocarditis, I40.8 — Other acute myocarditis, I40.9 — Acute myocarditis, unspecified, +19 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Rheumatic”, “Insufficiency, insufficient”, “Degeneration, degenerative”, …; these codes share that main term but sit in a different category of the Tabular List.

H35.44 — Age-related reticular degeneration of retina (retina, peripheral, senile reticular), H35.45 — Secondary pigmentary degeneration (retina, peripheral, secondary, pigmentary), H35.46 — Secondary vitreoretinal degeneration (retina, peripheral, secondary, vitreoretinal), H35.9 — Unspecified retinal disorder (retina), H43.81 — Vitreous degeneration (vitreous), H50.9 — Unspecified strabismus (muscle, ocular NEC), H51.11 — Convergence insufficiency (convergence), H51.8 — Other specified disorders of binocular movement (divergence), H52.4 — Presbyopia (accommodation, old age), I00 — Rheumatic fever without heart involvement (pneumonia), I02.0 — Rheumatic chorea with heart involvement (myocarditis, with chorea), I05.1 — Rheumatic mitral insufficiency (mitral, rheumatic), I05.2 — Rheumatic mitral stenosis with insufficiency (mitral, with, obstruction or stenosis), I06.1 — Rheumatic aortic insufficiency (aortic, rheumatic), I06.2 — Rheumatic aortic stenosis with insufficiency (aortic, rheumatic, with, stenosis), I07.1 — Rheumatic tricuspid insufficiency (tricuspid), I07.2 — Rheumatic tricuspid stenosis and insufficiency (tricuspid, with, obstruction or stenosis), I07.9 — Rheumatic tricuspid valve disease, unspecified (tricuspid), I08.0 — Rheumatic disorders of both mitral and aortic valves (aortic, with, mitraldisease), I08.1 — Rheumatic disorders of both mitral and tricuspid valves (tricuspid, with, mitraldisease), +228 more

Contextual Map

Every relationship of I01.2 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 I01.2 with these 3 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Clinical classification (CCSR)

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

Index entries

  • Degeneration, degenerative, myocardial, myocardium (fatty) (hyaline) (senile), with rheumatic fever (conditions in I00), active, acute or subacute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Insufficiency, insufficient, myocardial, myocardium (with arteriosclerosis), rheumatic, active, acute, or subacute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Insufficiency, insufficient, myocardial, myocardium (with arteriosclerosis), with, rheumatic fever (conditions in I00), active, acute or subacute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Myocarditis (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile), active, rheumatic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Myocarditis (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile), acute or subacute (interstitial), due to, streptococcus (beta-hemolytic)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Myocarditis (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile), acute or subacute (interstitial), rheumatic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Myocarditis (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile), rheumatic (chronic) (inactive) (with chorea), active or acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Rheumatic (acute) (subacute), myocarditis (chronic) (inactive) (with chorea), active or acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

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
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. "I01.2 — Acute rheumatic myocarditis." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/i01.2-acute-rheumatic-myocarditis

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Acute rheumatic myocarditis

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.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to I01.2 in its code family, with their registry titles.

View all codes in the I01 family