ICD-10-CM 2027
ICD-10 code for carditis
From the official ICD-10-CM alphabetic index entry “Carditis (acute) (bacterial) (chronic) (subacute)”. Page updated September 29, 2026.
About coding carditis
The ICD-10-CM code for carditis is I51.89 (Other ill-defined heart diseases). The official index lists 2 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on I51.89.
Within I51.8, choose I51.89 (Other ill-defined heart diseases) only when documentation doesn't support a more specific option: Takotsubo syndrome (I51.81).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 302 (Atherosclerosis with MCC, relative weight 1.1984) and DRG 303 (Atherosclerosis without MCC, relative weight 0.6612), 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.
More specific carditis codes (official index)
Common questions about carditis ICD-10 codes
What is the ICD-10 code for carditis?
- I51.89 — Other ill-defined heart diseases. More specific codes apply when the documentation supports them: A39.50, B33.20.
What is the ICD-10 code for meningococcal carditis?
- A39.50 — Meningococcal carditis, unspecified.
What is the ICD-10 code for viral carditis?
- B33.20 — Viral carditis, unspecified.
Is I51.89 billable?
- Yes. I51.89 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I51.89 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I51.89 as a principal diagnosis.
Is I51.89 a CC or MCC?
- No. I51.89 is neither a CC nor an MCC under MS-DRG v44.0.