2026 ICD-10-CM Diagnosis Code I09.0Rheumatic myocarditis

ICD-10-CM Codes›I00–I99›I05-I09›I09

ICD-10-CM I09.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I09.0 is a billable ICD-10-CM diagnosis code for rheumatic myocarditis. 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. Coders also document this condition as carditis due to rheumatic fever. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Chronic rheumatic heart disease and Myocarditis and cardiomyopathy.

Code Identity

ICD-10-CM Code
I09.0
Billable Status
Yes — Valid for Submission
Code Describes
Rheumatic myocarditis
Short Description
Rheumatic myocarditis
Same as the full description in the CMS dataset.
Parent Code
I09
Other rheumatic heart diseases

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI05-I09Chronic rheumatic heart diseases
CategoryI09Other rheumatic heart diseases
This CodeI09.0Rheumatic myocarditis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Carditis due to rheumatic fever
  • Chronic myocarditis
  • Chronic rheumatic carditis
  • Chronic rheumatic myocarditis
  • Myocarditis due to autoimmune disease
  • Rheumatic cardiomyopathy
  • Rheumatoid myocarditis

Tabular List NotesGuidance

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

Type 1 Excludes

  • myocarditis not specified as rheumatic I51.4

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Cardiomyopathy(familial) (idiopathic)
      • rheumatic
    • Degeneration, degenerative
      • myocardial, myocardium (fatty) (hyaline) (senile)
        • with rheumatic fever (conditions in I00)
    • Degeneration, degenerative
      • myocardial, myocardium (fatty) (hyaline) (senile)
        • with rheumatic fever (conditions in I00)
          • inactive or quiescent (with chorea)
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • rheumatic (active) (acute) (chronic) (subacute)
        • inactive or quiescent with
          • myocarditis, myocardial degeneration (conditions in I51.4)
    • Insufficiency, insufficient
      • myocardial, myocardium (with arteriosclerosis)
        • with
          • rheumatic fever (conditions in I00)
    • Insufficiency, insufficient
      • myocardial, myocardium (with arteriosclerosis)
        • with
          • rheumatic fever (conditions in I00)
            • inactive or quiescent (with chorea)
    • Insufficiency, insufficient
      • myocardial, myocardium (with arteriosclerosis)
        • rheumatic
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • with
        • rheumatic fever (conditions in I00)
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • with
        • rheumatic fever (conditions in I00)
          • inactive or quiescent (with chorea)
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • rheumatic (chronic) (inactive) (with chorea)
    • Rheumatic(acute) (subacute)
      • degeneration, myocardium
    • Rheumatic(acute) (subacute)
      • myocarditis (chronic) (inactive) (with chorea)

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR001
Chronic rheumatic heart disease
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR CIR005
Myocarditis and cardiomyopathy
Default principal diagnosis: inpatient No · outpatient No

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 I09.0 to ICD-9-CMHistory

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

ICD-9-CM
398.0 Rheumatic myocarditis
Exact Match The mapping is direct, with no qualifiers.

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 I09.0Overview

Is I09.0 (Other rheumatic heart diseases) a billable code?

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

What MS-DRG does I09.0 group to?

When rheumatic myocarditis 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.

What is the ICD-9 equivalent of I09.0?

Under the General Equivalence Mappings, rheumatic myocarditis converts to ICD-9-CM 398.0 (rheumatic myocarditis). The mapping is a direct match.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.