ICD-10-CM 2027
ICD-10 code for STEMI
ST elevation (STEMI) myocardial infarction of unspecified site
From the official ICD-10-CM alphabetic index entry “STEMI”. Page updated September 29, 2026.
About coding STEMI
The ICD-10-CM code for STEMI is I21.3 (ST elevation (STEMI) myocardial infarction of unspecified site).
Within I21, choose I21.3 (ST elevation (STEMI) myocardial infarction of unspecified site) only when documentation doesn't support a more specific option: ST elevation (STEMI) myocardial infarction of anterior wall (I21.0), ST elevation (STEMI) myocardial infarction of inferior wall (I21.1), ST elevation (STEMI) myocardial infarction of other sites (I21.2), Non-ST elevation (NSTEMI) myocardial infarction (I21.4), unspecified (I21.9), other type of myocardial infarction (I21.A) and myocardial infarction with coronary microvascular dysfunction (I21.B).
Use an additional code, if applicable, to identify: exposure to environmental tobacco smoke (Z77.22), history of tobacco dependence (Z87.891), occupational exposure to environmental tobacco smoke (Z57.31), status post administration of tPA (rtPA) in a different facility within the last 24 hours prior to admission to current facility (Z92.82), tobacco dependence (F17.-) and 1 more.
As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.
Common questions about STEMI ICD-10 codes
What is the ICD-10 code for STEMI?
- I21.3 — ST elevation (STEMI) myocardial infarction of unspecified site.
Is I21.3 billable?
- Yes. I21.3 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I21.3 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I21.3 as a principal diagnosis.
Is I21.3 a CC or MCC?
- I21.3 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.