2026 ICD-10-CM Diagnosis Code I01.2Acute rheumatic myocarditis

ICD-10-CM Codes›I00–I99›I00-I02›I01

ICD-10-CM I01.2
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I01.2 is a billable ICD-10-CM diagnosis code for acute 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 acute rheumatic carditis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acute rheumatic heart disease and Myocarditis and cardiomyopathy.

Code Identity

ICD-10-CM Code
I01.2
Billable Status
Yes — Valid for Submission
Code Describes
Acute rheumatic myocarditis
Short Description
Acute rheumatic myocarditis
Same as the full description in the CMS dataset.
Parent Code
I01
Rheumatic fever with heart involvement

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI00-I02Acute rheumatic fever
CategoryI01Rheumatic fever with heart involvement
This CodeI01.2Acute rheumatic myocarditis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute rheumatic carditis
  • Acute rheumatic fever
  • Acute rheumatic heart disease
  • Acute rheumatic myocarditis

Tabular List NotesGuidance

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

Inclusion Terms

  • Any condition in I00

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.

    • Degeneration, degenerative
      • myocardial, myocardium (fatty) (hyaline) (senile)
        • with rheumatic fever (conditions in I00)
          • active, acute or subacute
    • Insufficiency, insufficient
      • myocardial, myocardium (with arteriosclerosis)
        • with
          • rheumatic fever (conditions in I00)
            • active, acute or subacute
    • Insufficiency, insufficient
      • myocardial, myocardium (with arteriosclerosis)
        • rheumatic
          • active, acute, or subacute
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • active
        • rheumatic
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • acute or subacute (interstitial)
        • due to
          • streptococcus (beta-hemolytic)
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • acute or subacute (interstitial)
        • rheumatic
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • rheumatic (chronic) (inactive) (with chorea)
        • active or acute
    • Rheumatic(acute) (subacute)
      • myocarditis (chronic) (inactive) (with chorea)
        • active or acute

Clinical ClassificationClinical

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

CCSR CIR002
Acute rheumatic heart disease
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR CIR005
Myocarditis and cardiomyopathy
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Acute Rheumatic Myocarditis

    inflammation of the myocardium in acute rheumatic heart disease.

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

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert I01.2 to ICD-9-CMHistory

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

ICD-9-CM
391.2 Ac 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 I01.2Overview

Is I01.2 (Rheumatic fever with heart involvement) a billable code?

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

What MS-DRG does I01.2 group to?

When acute 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 I01.2?

Under the General Equivalence Mappings, acute rheumatic myocarditis converts to ICD-9-CM 391.2 (ac rheumatic myocarditis). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.