2026 ICD-10-CM Diagnosis Code I01.1Acute rheumatic endocarditis

ICD-10-CM Codes›I00–I99›I00-I02›I01

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

I01.1 is a billable ICD-10-CM diagnosis code for acute rheumatic endocarditis. 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. 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
I01.1
Billable Status
Yes — Valid for Submission
Code Describes
Acute rheumatic endocarditis
Short Description
Acute rheumatic endocarditis
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 CodeI01.1Acute rheumatic endocarditis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute rheumatic aortitis
  • Acute rheumatic carditis
  • Acute rheumatic endocarditis
  • Acute rheumatic fever
  • Acute rheumatic heart disease
  • Acute rheumatic valvulitis
  • Endocarditis associated with another disorder
  • Rheumatoid aortitis
  • Rheumatoid arteritis

Tabular List NotesGuidance

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

Inclusion Terms

  • Any condition in I00
  • Acute rheumatic valvulitis

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.

    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • acute or subacute
        • rheumatic (aortic) (mitral) (pulmonary) (tricuspid)
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • aortic (heart) (nonrheumatic) (valve)
        • with
          • mitral disease
            • active or acute
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • aortic (heart) (nonrheumatic) (valve)
        • rheumatic
          • with mitral disease
            • active or acute
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • aortic (heart) (nonrheumatic) (valve)
        • rheumatic
          • active or acute
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • mitral (chronic) (double) (fibroid) (heart) (inactive) (valve) (with chorea)
        • with
          • aortic (valve) disease
            • active or acute
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • mitral (chronic) (double) (fibroid) (heart) (inactive) (valve) (with chorea)
        • active or acute
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • pulmonary (chronic) (heart) (valve)
        • acute or subacute
          • rheumatic
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • pulmonary (chronic) (heart) (valve)
        • rheumatic (chronic) (inactive) (with chorea)
          • active or acute
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • rheumatic (chronic) (inactive) (with chorea)
        • active or acute (aortic) (mitral) (pulmonary) (tricuspid)
    • Endocarditis(chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
      • tricuspid (chronic) (heart) (inactive) (rheumatic) (valve) (with chorea)
        • active or acute
    • Insufficiency, insufficient
      • mitral (valve)
        • rheumatic
          • active or acute
    • Stenosis, stenotic(cicatricial)
      • mitral (chronic) (inactive) (valve)
        • 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 CIR004
Endocarditis and endocardial disease
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Endocarditis

Endocarditis is sometimes called infective endocarditis. It's a rare but life-threatening inflammation of the lining inside your heart's chambers and valves (the endocardium).

The full article covers:

  • What is endocarditis?
  • What causes endocarditis?
  • Who is more likely to develop endocarditis?
  • What are the symptoms of endocarditis?
  • What other problems can endocarditis cause?
  • How is endocarditis diagnosed?
  • What are the treatments for endocarditis?
  • Can endocarditis be prevented?

Read the full article at MedlinePlus

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

Convert I01.1 to ICD-9-CMHistory

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

ICD-9-CM
391.1 Acute rheumatic endocard
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 I01.1Overview

Is I01.1 (Rheumatic fever with heart involvement) a billable code?

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

What MS-DRG does I01.1 group to?

When acute rheumatic endocarditis 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 I01.1?

Under the General Equivalence Mappings, acute rheumatic endocarditis converts to ICD-9-CM 391.1 (acute rheumatic endocard). 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.