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I21 ICD-10-CM Code: Acute myocardial infarction

I21 isn’t billable on its own. Choose one of the 13 billable codes beneath it, the one the documentation supports.

Official description

I21

Acute myocardial infarction

ICD-10-CM diagnosis code · United States clinical modification

Billable codes under I21

I21 can’t be reported on its own. Choose the code below that matches what the note documents.

Where I21 sits

  1. 1

    Chapter 9

    Diseases of the circulatory system (I00-I99)

  2. 2

    Section

    Ischemic heart diseases (I20-I25)

  3. 3

    Category I21

    Acute myocardial infarction

  4. 4

    Code I21

    Acute myocardial infarction

Notes 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

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.

Review the CDC/NCHS ICD-10-CM 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 13 billable codes beneath it 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.-).