I21

Non-billable

Acute myocardial infarction

I21 is the ICD-10-CM code for Acute myocardial infarction. It is a non-billable category code — use a more specific child code such as I21.0 for billing.

Status
Header (non-billable)
Chapter
I00-I99
Subcodes
8
Edition
FY2026

I00-I99 Diseases of the circulatory system

What this means — in plain language

MedlinePlus · NIH

Each year almost 800,000 Americans have a heart attack. A heart attack happens when blood flow to the heart suddenly becomes blocked. Without the blood coming in, the heart can't get oxygen. If not treated quickly, the heart muscle begins to die. But if you do get quick treatment, you may be able to prevent or limit damage to the heart muscle. That's why it's important to know the symptoms of a heart attack and call…

Read more about Heart Attack at MedlinePlus ↗

Source: U.S. National Library of Medicine (MedlinePlus). Informational only — not medical advice.

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

  • 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)

Medications indicated for this condition

FDA labeling

Drugs whose FDA labeling lists this condition's category among its indications. Informational only — not a treatment recommendation or medical advice.

Conditions mapped to this code

MedlinePlus · NIH

Plain-language health-topic references grounded in MedlinePlus (NIH/NLM).

Frequently asked questions

What is ICD-10 code I21?
I21 is the ICD-10-CM code for "Acute myocardial infarction". It falls under I00-I99 Diseases of the circulatory system.
Is I21 a billable code?
No — I21 is a non-billable header code. Use a more specific child code (such as I21.0) for billing.
What are the subcodes of I21?
I21 has 8 more specific child codes, including I21.0, I21.1, I21.2.

Source: CMS ICD-10-CM FY2026. For informational purposes only — not medical advice. See our medical disclaimer.

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