Acute myocarditis (I40) ICD-10-CM
The I40 code range covers acute myocarditis with 5 ICD-10-CM diagnosis codes. 4 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Includes
This note appears immediately under a three character code title to further define, or give examples of, the content of the category.
- subacute myocarditis
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- acute rheumatic myocarditis I01.2
Codes in the I40 Range 5 codes · 4 billable
About the I40 Code Range
ICD-10 codes in the I40 category cover different types of acute myocarditis, an inflammation of the heart muscle. These codes help healthcare providers specify the exact cause or nature of the myocarditis for accurate diagnosis and treatment documentation.
The general code I40 denotes acute myocarditis. More specific subcodes include I40.0 for infective myocarditis, which includes infections caused by bacteria, fungi, parasites, or viruses—terms like septic myocarditis and fungal myocarditis identify this category. Code I40.1 represents isolated myocarditis, also known by terms like eosinophilic or giant cell myocarditis. I40.8 covers other acute myocarditis types, including toxic and drug-induced forms. For cases without a defined cause, I40.9 applies to acute myocarditis, unspecified, which might be recorded as subacute or interstitial myocarditis. Medical coders searching for the right ICD-10 code for acute myocarditis can use these distinctions to ensure precise coding that reflects the myocarditis type or cause reported in patient care.
Questions About This Page
How many billable codes are in the I40 range?
Of the 5 codes in this range, 4 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the I40 range classify?
The range classifies acute myocarditis. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
