I21
⚠ Non-billable
Acute myocardial infarction
ICD-10-CM · FY2026 · Diseases of the Circulatory System
Code
I21
System
ICD-10-CM
Billable
No — use specific code
Effective
FY2026
Chapter
Diseases of the Circulatory System
Source
CMS / CDC NCHS
⚠ Verify before billing. Confirm against the current CMS/NCHS ICD-10-CM files and your payer's rules before claims submission.
Official coding notes
From CMS's ICD-10-CM Tabular List.
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, but may code together
- old myocardial infarction (I25.2)
- postmyocardial infarction syndrome (I24.1)
- subsequent type 1 myocardial infarction (I22.-)
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)
Frequently asked questions
What is ICD-10 code I21?
ICD-10-CM code I21 represents Acute myocardial infarction. It is a non-billable header code requiring a more specific subcategory in the Diseases of the Circulatory System chapter, effective October 1, 2025 – September 30, 2026.
Is I21 billable?
No. I21 is a non-billable header. Select a more specific subcategory for claims submission.
What chapter is I21 in?
I21 belongs to the Diseases of the Circulatory System chapter (I00–I99) of ICD-10-CM.
Related codes in the I21 category
I21.0
ST elevation (STEMI) myocardial infarction of anterior wall
Non-billable
I21.1
ST elevation (STEMI) myocardial infarction of inferior wall
Non-billable
I21.2
ST elevation (STEMI) myocardial infarction of other sites
Non-billable
I21.3
ST elevation (STEMI) myocardial infarction of unspecified site
Billable
I21.4
Non-ST elevation (NSTEMI) myocardial infarction
Billable
I21.9
Acute myocardial infarction, unspecified
Billable
I21.A
Other type of myocardial infarction
Non-billable
I21.B
Myocardial infarction with coronary microvascular dysfunction
Billable
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