2026 ICD-10-CM Diagnosis Code I40.0Infective myocarditis

ICD-10-CM Codes›I00–I99›I30-I5A›I40

ICD-10-CM I40.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I40.0 is a billable ICD-10-CM diagnosis code for infective myocarditis. 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, 974 through 976. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myocarditis and cardiomyopathy.

Code Identity

ICD-10-CM Code
I40.0
Billable Status
Yes — Valid for Submission
Code Describes
Infective myocarditis
Short Description
Infective myocarditis
Same as the full description in the CMS dataset.
Parent Code
I40
Acute myocarditis

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI40Acute myocarditis
This CodeI40.0Infective myocarditis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abscess of myocardium
  • Bacterial myocarditis
  • Cardiovascular abnormality due to infective myocarditis
  • Dilated cardiomyopathy due to bacterial myocarditis
  • Dilated cardiomyopathy due to infectious disease
  • Dilated cardiomyopathy due to parasitic myocarditis
  • Enterovirus heart infection
  • Fungal myocarditis
  • Myocarditis caused by Aspergillus
  • Myocarditis caused by Borrelia
  • Myocarditis caused by Candida
  • Myocarditis caused by echovirus
  • Myocarditis caused by Rickettsia
  • Myocarditis caused by Spirochaetales
  • Myocarditis due to infectious agent
  • Parasitic myocarditis
  • Protozoan myocarditis
  • Septic myocarditis - pneumococcal
  • Septic myocarditis - staphylococcal
  • Septic myocarditis - streptococcal

Tabular List NotesGuidance

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

Inclusion Terms

  • Septic myocarditis

Use Additional Code

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.

    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • myocardium
    • Infection, infected, infective(opportunistic)
      • myocardium NEC
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • bacterial (acute)
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • infective
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • pneumococcal
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • septic
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • staphylococcal
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • suppurative

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR005
Myocarditis and cardiomyopathy
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Bacterial Myocarditis

    myocarditis that is caused by an infection with a bacterial agent.

Patient EducationClinical

Cardiomyopathy

Cardiomyopathy is the name for diseases of the heart muscle. These diseases enlarge your heart muscle or make it thicker and more rigid than normal. In rare cases, scar tissue replaces the muscle tissue.

Read the full article at MedlinePlus

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

Convert I40.0 to ICD-9-CMHistory

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

ICD-9-CM
422.91 Idiopathic myocarditis
Approximate The match is approximate rather than exact.
ICD-9-CM
422.92 Septic myocarditis
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 I40.0Overview

Is I40.0 (Acute myocarditis) a billable code?

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

What MS-DRG does I40.0 group to?

When infective myocarditis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, 974, 975, 976, with relative weights from 0.6821 to 2.8860 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I40.0?

Under the General Equivalence Mappings, infective myocarditis converts to ICD-9-CM 422.91 (idiopathic myocarditis) and 422.92 (septic myocarditis). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.