I21 ICD-10-CM Code: Acute myocardial infarction
A clear reference for the official code description, hierarchy, and related coding information from the FY 2027 U.S. release.
Official description
I21Acute myocardial infarction
ICD-10-CM diagnosis code · United States clinical modification
Where I21 sits
- 1
Chapter 9
Diseases of the circulatory system (I00-I99)
- 2
Section
Ischemic heart diseases (I20-I25)
- 3
Category I21
Acute myocardial infarction
- 4
Code I21
Acute myocardial infarction
Codes under I21
I21 is a non-billable category. Choose the child code that best matches the documented diagnosis.
I21.0ST elevation (STEMI) myocardial infarction of anterior wallI21.1ST elevation (STEMI) myocardial infarction of inferior wallI21.2ST elevation (STEMI) myocardial infarction of other sitesI21.3ST elevation (STEMI) myocardial infarction of unspecified siteI21.4Non-ST elevation (NSTEMI) myocardial infarctionI21.9Acute myocardial infarction, unspecifiedI21.AOther type of myocardial infarctionI21.BMyocardial infarction with coronary microvascular dysfunctionNotes for this code
Inclusion terms
No inclusion terms are listed for I21.
Code first
No “code first” instruction is listed for I21.
Use additional code
- 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)
Excludes1
Conditions that should not be reported together with this code.
No Excludes1 note is listed for I21.
Excludes2
Conditions not included here that may be reported separately when present.
- old myocardial infarction (I25.2)
- postmyocardial infarction syndrome (I24.1)
- subsequent type 1 myocardial infarction (I22.-)
Source and release
- Data release
- U.S. ICD-10-CM · FY 2027
- Effective date
- Oct 1, 2026
- Publisher
- Vero Scribe Inc.
This reference is generated from Vero’s ICD-10-CM description, hierarchy, and code-note dataset. The visible content and structured data share that source.
Frequently asked questions
What does ICD-10-CM code I21 mean?
I21 is the FY 2027 U.S. ICD-10-CM code for “Acute myocardial infarction.”
Is I21 a billable or specific ICD-10-CM code?
No. I21 has more specific child codes in the FY 2027 reference data. Select the code that matches the documentation and confirm the active code set and payer requirements.
Where is I21 located in ICD-10-CM?
I21 is listed in Chapter 9, Diseases of the circulatory system (I00-I99), within Ischemic heart diseases (I20-I25) (I20–I25), under category I21, Acute myocardial infarction.
What coding notes are listed for I21?
No inclusion terms are listed for I21 in this reference record. No code-first instruction is listed. Additional-code instructions: 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). No Excludes1 note is listed. Excludes2 notes: old myocardial infarction (I25.2); postmyocardial infarction syndrome (I24.1); subsequent type 1 myocardial infarction (I22.-).