I21.1 – ST elevation (STEMI) myocardial infarction of inferior wall

ICD-10-CM 2027 diagnosis code · Ischemic heart diseases

Non-billable header

ICD-10-CM code I21.1
Code
I21.1 (claims format: I211)
Description
ST elevation (STEMI) myocardial infarction of inferior wall
Billable
No – use a more specific code below
Valid for
Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter
9. Diseases of the circulatory system (I00-I99)
Block
I20-I25 Ischemic heart diseases
Parent codes
I21

Billable codes under I21.1

I21.1 is a header code and cannot be used on claims. Choose the most specific code:

Notes for I21.1

Applicable to:
  • Type 1 ST elevation myocardial infarction of inferior wall

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

I21 – Acute myocardial infarction

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)

Block I20-I25

Code also:
  • the presence of hypertension (I10-I1A)

Related codes in I21

Frequently asked questions

What is ICD-10 code I21.1?

I21.1 is the ICD-10-CM code for sT elevation (STEMI) myocardial infarction of inferior wall, in the block I20-I25 (Ischemic heart diseases).

Is I21.1 a billable code?

No. I21.1 is a header code with more specific child codes; report one of the billable codes listed above.

What category does I21.1 belong to?

It belongs to category I21 – Acute myocardial infarction.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.