2026 ICD-10-CM Diagnosis Code B33.22Viral myocarditis

ICD-10-CM Codes›A00–B99›B25-B34›B33

ICD-10-CM B33.22
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B33.22 is a billable ICD-10-CM diagnosis code for viral 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myocarditis and cardiomyopathy and Viral infection.

Code Identity

ICD-10-CM Code
B33.22
Billable Status
Yes — Valid for Submission
Code Describes
Viral myocarditis
Short Description
Viral myocarditis
Same as the full description in the CMS dataset.
Parent Code
B33.2
Viral carditis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB25-B34Other viral diseases
CategoryB33Other viral diseases, not elsewhere classified
This CodeB33.22Viral myocarditis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute aseptic myocarditis of the newborn
  • Acute myocarditis
  • Acute myocarditis - coxsackie
  • Acute viral carditis
  • Adenoviral myocarditis
  • Coxsackie carditis
  • Coxsackie myocarditis
  • Coxsackie myocarditis of newborn
  • Enterovirus heart infection
  • Myocarditis caused by Influenza A virus
  • Myocarditis caused by Influenza A virus subtype H1N1
  • Myocarditis caused by influenza virus
  • Neonatal coxsackie virus syndrome
  • Viral myocarditis

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.

    • Coxsackie(virus) (infection)
      • myocarditis
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • aseptic of newborn
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • Coxsackie (virus)
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • epidemic of newborn (Coxsackie)
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • virus, viral
    • Myocarditis(with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
      • virus, viral
        • of newborn (Coxsackie)

Clinical ClassificationClinical

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

CCSR CIR005
Myocarditis and cardiomyopathy
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR INF008
Viral infection
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Acute Myocarditis

    the sudden onset of inflammation of heart muscle with myocellular necrosis; this is generally secondary to an infectious cause, and patients often have a recent history of a flu-like illness.

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 B33.22 to ICD-9-CMHistory

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

ICD-9-CM
074.23 Coxsackie 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 B33.22Overview

Is B33.22 (Viral carditis) a billable code?

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

What MS-DRG does B33.22 group to?

When viral myocarditis 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.

What is the ICD-9 equivalent of B33.22?

Under the General Equivalence Mappings, viral myocarditis converts to ICD-9-CM 074.23 (coxsackie 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.