2026 ICD-10-CM Diagnosis Code I01.9Acute rheumatic heart disease, unspecified

ICD-10-CM Codes›I00–I99›I00-I02›I01

ICD-10-CM I01.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I01.9 is a billable ICD-10-CM diagnosis code for acute rheumatic heart disease, unspecified. 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 Endocarditis and endocardial disease.

Code Identity

ICD-10-CM Code
I01.9
Billable Status
Yes — Valid for Submission
Code Describes
Acute rheumatic heart disease, unspecified
Short Description
Acute rheumatic heart disease, unspecified
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 CodeI01.9Acute rheumatic heart disease, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

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

Tabular List NotesGuidance

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

Inclusion Terms

  • Any condition in I00
  • Rheumatic carditis, acute
  • Rheumatic heart disease, active or acute

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.

    • Bouillaud's disease or syndrome(rheumatic heart disease)
    • Disease, diseased
      • Bouillaud's (rheumatic heart disease)
    • Disease, diseased
      • heart (organic)
        • with
          • rheumatic fever (conditions in I00)
            • active
    • Disease, diseased
      • heart (organic)
        • rheumatic (chronic) (inactive) (old) (quiescent) (with chorea)
          • active or acute
    • Syndrome
      • Bouillaud's

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 CIR004
Endocarditis and endocardial disease
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Heart Valve Diseases

Heart valve disease happens when one or more of your heart valves don't work well.

The full article covers:

  • What are heart valve diseases?
  • What are the types of heart valve diseases?
  • What causes heart valve diseases?
  • Who is more likely to develop heart valve diseases?
  • What are the symptoms of heart valve diseases?
  • What other problems can heart valve diseases cause?
  • How is heart valve disease diagnosed?
  • What are the treatments for heart valve diseases?

Read the full article at MedlinePlus

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

Convert I01.9 to ICD-9-CMHistory

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

ICD-9-CM
391.9 Ac rheumat hrt dis NOS
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 I01.9Overview

Is I01.9 (Rheumatic fever with heart involvement) a billable code?

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

What MS-DRG does I01.9 group to?

When acute rheumatic heart disease, unspecified 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 I01.9?

Under the General Equivalence Mappings, acute rheumatic heart disease, unspecified converts to ICD-9-CM 391.9 (ac rheumat hrt dis NOS). 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.