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ICD-10-CM 2027 diagnosis code

I01.0Acute rheumatic pericarditis

✓ Billable / specificCC — complication/comorbidity

I01.0 is a valid, billable ICD-10-CM code for acute rheumatic pericarditis. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for Rheumatic pericarditis, ICD-10 code for Pericarditis rheumatic.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About I01.0

I01.0 is the ICD-10-CM diagnosis code for acute rheumatic pericarditis. It belongs to category I01 (rheumatic fever with heart involvement), block I00-I02 (acute rheumatic fever) and chapter 9 (diseases of the circulatory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within I01 (rheumatic fever with heart involvement), I01.0 is specifically for acute rheumatic pericarditis. Related codes cover acute rheumatic endocarditis (I01.1), acute rheumatic myocarditis (I01.2), other acute rheumatic heart disease (I01.8) and acute rheumatic heart disease, unspecified (I01.9).

Don't report I01.0 together with the conditions in its Excludes1 note: acute pericarditis not specified as rheumatic (I30.-).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 314 (Other Circulatory System Diagnoses with MCC, relative weight 2.0873), DRG 315 (Other Circulatory System Diagnoses with CC, relative weight 0.9508) and DRG 316 (Other Circulatory System Diagnoses without CC/MCC, relative weight 0.6677), in MDC 05 (Diseases and Disorders of the Circulatory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 391.0 (acute rheumatic pericarditis).

Coding notes

Applicable toConditions and synonyms classified to this code
  • Any condition in I00 with pericarditis
  • Rheumatic pericarditis (acute)
Excludes1Not coded here — never report together with this code
  • acute pericarditis not specified as rheumatic (I30.-)

Notes that apply from higher levels

Instructions written at a parent level also apply to I01.0.

› From I01 Rheumatic fever with heart involvement
Excludes1
  • chronic diseases of rheumatic origin (I05-I09) unless rheumatic fever is also present or there is evidence of reactivation or activity of the rheumatic process.

Broader instructions also apply from Chapter 9: Diseases of the circulatory system.

Alphabetic index entries

3 entries

Terms in the official ICD-10-CM index that lead to I01.0.

Codes whose notes reference I01.0

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 391.0Acute rheumatic pericarditisexact

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about I01.0

Is I01.0 billable?

Yes. I01.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can I01.0 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict I01.0 as a principal diagnosis.

Is I01.0 a CC or MCC?

I01.0 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does I01.0 group to?

I01.0 is used in the MS-DRG v44.0 logic for MS-DRG 314 (Other Circulatory System Diagnoses with MCC), MS-DRG 315 (Other Circulatory System Diagnoses with CC) and MS-DRG 316 (Other Circulatory System Diagnoses without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for I01.0?

The CMS General Equivalence Mappings map I01.0 to ICD-9-CM 391.0.