2026 ICD-10-CM Diagnosis Code I05.9Rheumatic mitral valve disease, unspecified

ICD-10-CM Codes›I00–I99›I05-I09›I05

ICD-10-CM I05.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I05.9 is a billable ICD-10-CM diagnosis code for rheumatic mitral valve disease, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 306 through 307. 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.

Code Identity

ICD-10-CM Code
I05.9
Billable Status
Yes — Valid for Submission
Code Describes
Rheumatic mitral valve disease, unspecified
Short Description
Rheumatic mitral valve disease, unspecified
Same as the full description in the CMS dataset.
Parent Code
I05
Rheumatic mitral valve diseases

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI05-I09Chronic rheumatic heart diseases
CategoryI05Rheumatic mitral valve diseases
This CodeI05.9Rheumatic mitral valve disease, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Carditis due to rheumatic fever
  • Chronic rheumatic carditis
  • Chronic rheumatic mitral valvulitis
  • Chronic rheumatic valvulitis
  • Chronic valvulitis
  • Disorder of mitral valve prosthesis
  • Endocarditis of prosthetic mitral valve
  • Inflammation associated with cardiac implant
  • Mitral valve disorder
  • Rheumatic disease of mitral valve

Tabular List NotesGuidance

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

Inclusion Terms

  • Rheumatic mitral (valve) disorder (chronic) NOS

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.

    • Disease, diseased
      • heart (organic)
        • mitral
    • Disease, diseased
      • mitral (valve)
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • mitral (chronic) (double) (fibroid) (heart) (inactive) (valve) (with chorea)
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • mitral (chronic) (double) (fibroid) (heart) (inactive) (valve) (with chorea)
        • 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
          • endocarditis
            • mitral (valve)
    • Lesion(s) (nontraumatic)
      • mitral

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

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 I05.9 to ICD-9-CMHistory

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

ICD-9-CM
394.9 Mitral valve dis NEC/NOS
Approximate The match is approximate rather than exact.

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 I05.9Overview

Is I05.9 (Rheumatic mitral valve diseases) a billable code?

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

What MS-DRG does I05.9 group to?

When rheumatic mitral valve disease, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 306, 307, with relative weights from 0.9132 to 1.5758 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I05.9?

Under the General Equivalence Mappings, rheumatic mitral valve disease, unspecified converts to ICD-9-CM 394.9 (mitral valve dis NEC/NOS). The mapping is approximate, so confirm the match fits the documentation.

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.