I21
ICD-10Non-billable categoryAcute myocardial infarction
Official ICD-10-CM descriptor (FY2026)
Acute myocardial infarction
I21 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.
Includes
- cardiac infarction
- coronary (artery) embolism
- coronary (artery) occlusion
- coronary (artery) rupture
- coronary (artery) thrombosis
- infarction of heart, myocardium, or ventricle
- myocardial infarction specified as acute or with a stated duration of 4 weeks (28 days) or less from onset
Excludes2
Not included here. The condition is not part of this code, but a patient may have both, and both codes may be reported together.
- old myocardial infarction (I25.2)
- postmyocardial infarction syndrome (I24.1)
- subsequent type 1 myocardial infarction (I22.-)
Use additional code
Report an additional code to identify the associated condition.
- 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.-)
- tobacco use (Z72.0)
More specific codes under I21
- I21.0ST elevation (STEMI) myocardial infarction of anterior wallcategory
- I21.1ST elevation (STEMI) myocardial infarction of inferior wallcategory
- I21.2ST elevation (STEMI) myocardial infarction of other sitescategory
- I21.3ST elevation (STEMI) myocardial infarction of unsp site
- I21.4Non-ST elevation (NSTEMI) myocardial infarction
- I21.9Acute myocardial infarction, unspecified
- I21.AOther type of myocardial infarctioncategory
- I21.BMyocardial infarction with coronary microvascular dysfnct
Where this code sits
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ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.