ICD-10-CM 2027
ICD-10 code for myocarditis
From the official ICD-10-CM alphabetic index entry “Myocarditis (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)”. Page updated September 29, 2026.
About coding myocarditis
The ICD-10-CM code for myocarditis is I51.4 (Myocarditis, unspecified). The official index lists 49 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on I51.4.
Within I51, choose I51.4 (Myocarditis, unspecified) only when documentation doesn't support a more specific option: cardiac septal defect, acquired (I51.0), rupture of chordae tendineae, not elsewhere classified (I51.1), rupture of papillary muscle, not elsewhere classified (I51.2), intracardiac thrombosis, not elsewhere classified (I51.3), myocardial degeneration (I51.5), Cardiomegaly (I51.7), other ill-defined heart diseases (I51.8) and heart disease, unspecified (I51.9).
Don't report I51.4 together with the conditions in its Excludes1 note: acute or subacute myocarditis (I40.-).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
More specific myocarditis codes (official index)
- with
- rheumatic fever (conditions in I00) I09.0 — Rheumatic myocarditis
- active
- inactive or quiescent (with chorea) I09.0 — Rheumatic myocarditis
- active I40.9 — Acute myocarditis, unspecified
- rheumatic I01.2 — Acute rheumatic myocarditis
- with chorea (acute) (rheumatic) (Sydenham's) I02.0 — Rheumatic chorea with heart involvement
- acute or subacute (interstitial) I40.9 — Acute myocarditis, unspecified
- due to
- streptococcus (beta-hemolytic) I01.2 — Acute rheumatic myocarditis
- idiopathic I40.1 — Isolated myocarditis
- rheumatic I01.2 — Acute rheumatic myocarditis
- with chorea (acute) (rheumatic) (Sydenham's) I02.0 — Rheumatic chorea with heart involvement
- specified NEC I40.8 — Other acute myocarditis
- aseptic of newborn B33.22 — Viral myocarditis
- bacterial (acute) I40.0 — Infective myocarditis
- Coxsackie (virus) B33.22 — Viral myocarditis
- diphtheritic A36.81 — Diphtheritic cardiomyopathy
- eosinophilic I40.1 — Isolated myocarditis
- epidemic of newborn (Coxsackie) B33.22 — Viral myocarditis
- Fiedler's (acute) (isolated) I40.1 — Isolated myocarditis
- giant cell (acute) (subacute) I40.1 — Isolated myocarditis
- gonococcal A54.83 — Gonococcal heart infection
- granulomatous (idiopathic) (isolated) (nonspecific) I40.1 — Isolated myocarditis
- hypertensive
- idiopathic (granulomatous) I40.1 — Isolated myocarditis
- in (due to)
- diphtheria A36.81 — Diphtheritic cardiomyopathy
- epidemic louse-borne typhus A75.0 — Epidemic louse-borne typhus fever due to Rickettsia prowazekii
- Lyme disease A69.29 — Other conditions associated with Lyme disease
- sarcoidosis D86.85 — Sarcoid myocarditis
- scarlet fever A38.1 — Scarlet fever with myocarditis
- toxoplasmosis (acquired) B58.81 — Toxoplasma myocarditis
- typhoid A01.02 — Typhoid fever with heart involvement
- typhus NEC A75.9 — Typhus fever, unspecified
- infective I40.0 — Infective myocarditis
- influenzal
- isolated (acute) I40.1 — Isolated myocarditis
- meningococcal A39.52 — Meningococcal myocarditis
- mumps B26.82 — Mumps myocarditis
- nonrheumatic, active I40.9 — Acute myocarditis, unspecified
- parenchymatous I40.9 — Acute myocarditis, unspecified
- pneumococcal I40.0 — Infective myocarditis
- rheumatic (chronic) (inactive) (with chorea) I09.0 — Rheumatic myocarditis
- active or acute I01.2 — Acute rheumatic myocarditis
- with chorea (acute) (rheumatic) (Sydenham's) I02.0 — Rheumatic chorea with heart involvement
- rheumatoid
- septic I40.0 — Infective myocarditis
- staphylococcal I40.0 — Infective myocarditis
- suppurative I40.0 — Infective myocarditis
- syphilitic (chronic) A52.06 — Other syphilitic heart involvement
- toxic I40.8 — Other acute myocarditis
- rheumatic
- tuberculous A18.84 — Tuberculosis of heart
- typhoid A01.02 — Typhoid fever with heart involvement
- valvular
- virus, viral B33.22 — Viral myocarditis
- of newborn (Coxsackie) B33.22 — Viral myocarditis
Don't confuse with (Excludes1 for I51.4)
- acute or subacute myocarditis (I40.-)
Common questions about myocarditis ICD-10 codes
What is the ICD-10 code for myocarditis?
- I51.4 — Myocarditis, unspecified. More specific codes apply when the documentation supports them: I09.0, I09.0, I40.9, I01.2 and others below.
What is the ICD-10 code for active myocarditis?
- I40.9 — Acute myocarditis, unspecified.
What is the ICD-10 code for acute or subacute myocarditis?
- I40.9 — Acute myocarditis, unspecified.
What is the ICD-10 code for aseptic of newborn myocarditis?
- B33.22 — Viral myocarditis.
What is the ICD-10 code for bacterial myocarditis?
- I40.0 — Infective myocarditis.
What is the ICD-10 code for coxsackie myocarditis?
- B33.22 — Viral myocarditis.
What is the ICD-10 code for diphtheritic myocarditis?
- A36.81 — Diphtheritic cardiomyopathy.
Is I51.4 billable?
- Yes. I51.4 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I51.4 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I51.4 as a principal diagnosis.
Is I51.4 a CC or MCC?
- No. I51.4 is neither a CC nor an MCC under MS-DRG v44.0.