I40.1 — Isolated myocarditis
Is I40.1 billable?
Yes — I40.1 is billable for FY2027. I40.1 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. I40.1 may be submitted for encounters from October 1, 2026 through September 30, 2027.
I40.1 at a glance
| Code | I40.1 |
|---|---|
| Description | Isolated myocarditis |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does I40.1 group to?
I40.1 sits in MDC 05 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 314Other Circulatory System Diagnoses with MCCmedical
- 315Other Circulatory System Diagnoses with CCmedical
- 316Other Circulatory System Diagnoses without CC/MCCmedical
As a secondary diagnosis, I40.1 is a major complication or comorbidity (MCC), which can move a stay into a higher-paying DRG.
How is I40.1 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to I40.1. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Abramov-Fiedler myocarditis (acute isolated myocarditis)
- Fiedler's › myocarditis
- Myocarditis › eosinophilic (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
- Myocarditis › Fiedler's (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
- Myocarditis › giant cell (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
- Myocarditis › granulomatous (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
- Myocarditis › idiopathic (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
- Myocarditis › isolated (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
- Syndrome › Fiedler's
- Myocarditis › acute or subacute › idiopathic (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile)
Inclusion terms
Alternative wording in documentation that is classified to I40.1.
- Fiedler's myocarditis
- Giant cell myocarditis
- Idiopathic myocarditis
Excludes1 — never code together — inherited from I40
The conditions below can never be reported together with I40.1 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- acute rheumatic myocarditis (I01.2)
Excludes2 — not included here — inherited from Chapter 9
The conditions below are not part of I40.1, but a patient may have both at the same time. When documentation supports it, I40.1 and the excluded code may both be reported.
- 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.-)
How long has I40.1 existed?
I40.1 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.