Alphabetic Index FY2027

I51.4

Myocarditis, unspecified

FY2027Chapter 9: Diseases of the circulatory system/I30–I5A Other forms of heart disease

BillableComplete code, valid to report
Care settingsHome Health Primary · MMTA - Cardiac and Circulatory

I51.4 (also written I514) is a billable ICD-10-CM diagnosis code for myocarditis, unspecified. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 10 codes in category I51 (Complications and ill-defined descriptions of heart disease). The Alphabetic Index lists it under 3 entries. Its coding notes include 1 Excludes1 entry and 11 Excludes2 entries.

Guidelines tip

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

Hypertension with heart failure or certain other heart conditions is assigned to category I11, with an additional code for the heart condition, unless the provider documents they are unrelated.

Guidelines I.C.9.a.1Hypertension with heart diseaseRead the official text

Excludes1

Not coded here. The listed conditions generally should not be reported together.

This code
  • acute or subacute myocarditis (I40.-)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Inherited from I51 Complications and ill-defined descriptions of heart disease
  • heart disease specified as rheumatic (I00-I09)
Also from chapter/block level (10 notes)
Inherited from Chapter 9 Diseases of the circulatory system
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • systemic connective tissue disorders (M30-M36)
  • transient cerebral ischemic attacks and related syndromes (G45.-)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Cardiac and Circulatory clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

Inclusion terms

Conditions classified to this code.

This code
  • Chronic (interstitial) myocarditis
  • Myocardial fibrosis
  • Myocarditis NOS

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 3 entries