2026 ICD-10-CM Diagnosis Code I01.0Acute rheumatic pericarditis
ICD-10-CM Codes›I00–I99›I00-I02›I01
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
I01.0 is a billable ICD-10-CM diagnosis code for acute rheumatic pericarditis. 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 17 closely related codes. Coders also document this condition as acute rheumatic fever. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acute rheumatic heart disease and Pericarditis and pericardial disease.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acute rheumatic fever
- Acute rheumatic heart disease
- Acute rheumatic pericarditis
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Any condition in I00
- Rheumatic pericarditis (acute)
Type 1 Excludes
- acute pericarditis not specified as rheumatic I30
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
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.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Acute Rheumatic Pericarditis
inflammation of the pericardium in acute rheumatic heart disease.
Patient EducationClinical
Pericardial Disorders
The pericardium is a membrane, or sac, that surrounds your heart. It holds the heart in place and helps it work properly. Problems with the pericardium include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I01.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I01.0Overview
What is the ICD-10 code for acute rheumatic pericarditis?
The ICD-10-CM code for acute rheumatic pericarditis is I01.0 (sometimes written as I010). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is I01.0 (Rheumatic fever with heart involvement) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report acute rheumatic pericarditis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does I01.0 group to?
When acute rheumatic pericarditis 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 I01.0 a CC or MCC?
CMS lists I01.0 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 17 closely related codes in its exclusion list.
What is the ICD-9 equivalent of I01.0?
Under the General Equivalence Mappings, acute rheumatic pericarditis converts to ICD-9-CM 391.0 (acute rheumatic pericard). The mapping is a direct match.
