2026 ICD-10-CM Diagnosis Code I09.0Rheumatic myocarditis
ICD-10-CM Codes›I00–I99›I05-I09›I09
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
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. 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 26 closely related codes. 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
Code Classification
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
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
myocardial, myocardium (with arteriosclerosis) See Also: Failure, heart; I50.9
rheumatic I09.0
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
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Convert I09.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I09.0Overview
What is the ICD-10 code for rheumatic myocarditis?
The ICD-10-CM code for rheumatic myocarditis is I09.0 (sometimes written as I090). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
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.
Is I09.0 a CC or MCC?
CMS lists I09.0 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 26 closely related codes in its exclusion list.
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.
