I40 vs I51.4
I40 (Acute myocarditis) compared with I51.4 (Myocarditis, unspecified), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. I51.4 carries an Excludes1 note covering I40: “acute or subacute myocarditis (I40.-)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| I40Acute myocarditis | I51.4Myocarditis, unspecified | |
|---|---|---|
| Billing status | Non-billable header | Billable |
| Classification | I00-I99 — Diseases of the Circulatory System (I00-I99) | I00-I99 — Diseases of the Circulatory System (I00-I99) |
| Definition | Acute myocarditis is a non-billable ICD-10-CM category code (I40). | Myocarditis, unspecified is a billable ICD-10-CM diagnosis code (I51.4). |
| Includes | subacute myocarditis | Chronic (interstitial) myocarditis Myocardial fibrosis Myocarditis NOS |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources