All ICD10 Codes

I21

Non-Billable
ChapterI00–I99
Rankcategory
Official Description

Acute myocardial infarction

Use a more specific code (4 billable, 4 non-billable)
I21.0ST elevation (STEMI) myocardial infarction of anterior wallhas subcodesI21.1ST elevation (STEMI) myocardial infarction of inferior wallhas subcodesI21.2ST elevation (STEMI) myocardial infarction of other siteshas subcodesI21.3ST elevation (STEMI) myocardial infarction of unspecified siteI21.4Non-ST elevation (NSTEMI) myocardial infarctionI21.9Acute myocardial infarction, unspecifiedI21.AOther type of myocardial infarctionhas subcodesI21.BMyocardial infarction with coronary microvascular dysfunction
Metadata & Insights
  • •Non-billable category (requires more specific sub-code).
  • •Chapter 9: Diseases of the Circulatory System (I00-I99).

CH9 Parent Instructions

Excludes2(Not included here. Code separately if applicable.)
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • systemic connective tissue disorders (M30-M36)
  • transient cerebral ischemic attacks and related syndromes (G45.-)

I20-I25 Parent Instructions

Code Also
  • the presence of hypertension (I10-I1A)

Instructional Notes

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. Code separately if applicable.)
  • 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)

Clinical Hierarchy

BillableHas subcodes
CH9Diseases of the circulatory system (I00-I99)
I20-I25Ischemic heart diseases (I20-I25)
I21Acute myocardial infarctionNot billable
I21.0ST elevation (STEMI) myocardial infarction of anterior wallSubcodes
I21.1ST elevation (STEMI) myocardial infarction of inferior wallSubcodes
I21.2ST elevation (STEMI) myocardial infarction of other sitesSubcodes
I21.3ST elevation (STEMI) myocardial infarction of unspecified siteBillable
I21.4Non-ST elevation (NSTEMI) myocardial infarctionBillable
I21.9Acute myocardial infarction, unspecifiedBillable
I21.AOther type of myocardial infarctionSubcodes
I21.BMyocardial infarction with coronary microvascular dysfunctionBillable

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to I21:

blockI20-I25
Ischemic heart diseases (I20-I25)
View context instructions
chapterCH9
Diseases of the circulatory system (I00-I99)
View context instructions

MS-DRG Classification

2026

No direct MS-DRG triggers identified.

Cross Reference

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